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Special Feature

Nephrology Quiz and Questionnaire: 2009Richard J. Glassock (Moderator)*; Participants: Joanne M. Bargman,† Biff F. Palmer,‡

Millie Samaniego,§ and Fernando C. Fervenza�

*Department of Medicine, Geffen School of Medicine at UCLA, Los Angeles, California; †Department of Medicine,Toronto General Hospital, Toronto, Ontario, Canada; ‡Department of Internal Medicine, University of TexasSouthwestern Medical Center, Dallas, Texas; §Division of Nephrology, Department of Medicine, University of MichiganMedical School, Ann Arbor, Michigan; and �Division of Nephrology and Hypertension, Mayo Clinic, Rochester,Minnesota

Clin J Am Soc Nephrol 5: 1141–1160, 2010. doi: 10.2215/CJN.00540110

T he Nephrology Quiz and Questionnaire returns to thepages of CJASN after an absence of 3 years, but it stillremains one of the most popular sessions at the annual

meeting of the American Society of Nephrology. The meeting in2009 in San Diego was no exception, with a full-house atten-dance, estimated at more than 800 eager nephrologists. Eightchallenging and educational cases were presented and dis-cussed by four able and skilled experts. The discussants wereasked to prepare vignettes of puzzling cases, each illustratingsome topical, challenging, or controversial aspect of diagno-sis or management of ESRD and dialysis (Dr. Bargman), fluidand electrolytes (Dr. Palmer), kidney transplantation (Dr.Samaniego), and glomerular disease (Dr. Fervenza). One or twosingle best answers questions followed each case presentation,which were addressed by the audience in a live electronicresponse system. In addition, several weeks before the meeting,the cases and questions (without the answers) were sent to allof the US nephrology training program directors as a question-naire. Their responses to the questions were tallied and pre-sented after the audience response but before the answers to thequiz and the analyses of the cases were given by the discus-sants.

Each discussant prepared a manuscript summarizing his orher discussion of the cases, an edited version of which serves asthe main text of this article. We hope that this “distillate” fromSan Diego will serve the subscribers to CJASN well and providesome fresh insights into the complexity and vibrancy of clinicalnephrology for those who were unable to attend (Richard J.Glassock, MD, Moderator).

Case 1: Joanne M. BargmanThe patient was a 59-year-old man from North Africa. A diag-nosis of ankylosing spondylitis was made in 1980 and wastreated with anti-inflammatory agents. In 2002, he was noted tohave significant proteinuria and microscopic hematuria. A re-nal biopsy demonstrated AA amyloidosis. He had slowly pro-

gressive renal impairment. In 2005, he underwent nephrectomyfor renal cell carcinoma. This resulted in worsening nephroticsyndrome and stage 5 chronic kidney disease. A peritonealdialysis (PD) catheter was inserted in July 2005, and the patientstarted on continuous ambulatory PD, 3 � 2 L exchangesduring the day and icodextrin exchanges overnight. He devel-oped anuria over the subsequent 2 months. Peritonitis wasdiagnosed on September 10, 2006, when he presented withabdominal pain and cloudy drainage fluid.

Examination of the PD drainage fluid revealed a white bloodcell count of 1870 � 106/L, 90% neutrophils. He was started onempiric therapy with intraperitoneal cefazolin and ceftazidime.Culture and sensitivity of the PD fluid revealed Acinetobactercalcoaceticus-baumanii complex that was resistant to cefazolin.He was continued on intraperitoneal ceftazidime. Fungal pro-phylaxis was given with oral mycostatin.

Subsequent PD fluid cell counts were as follows:

• September 12: �100/L• September 14: �100/L• September 16: �100/L• September 20: 1360 � 106/L, 96% neutrophils

Question 1With respect to the increase in cell count on day 10 (September20) of therapy, which ONE of the following statements is MOSTcorrect (Figure 1)?

A. It is unlikely to be fungal because of the prophylaxis withmycostatin.

B. The most likely cause is that the patient stopped taking hisintraperitoneal antibiotic.

C. The causative organism became resistant to the antibiotic.D. The icodextrin has led to a chemical peritonitis via contam-

ination with peptidoglycans.E. The blood levels of ceftazidime became subtherapeutic.

Discussion of Case 1 (Question 1)The best answer is choice C: The causative organism becameresistant to the antibiotic. Acinetobacter calcoaceticus-baumaniibelongs to the SPICE group of organisms. This is an acronymfor a group of bacteria that have chromosomally mediated

Published online ahead of print. Publication date available at www.cjasn.org.

Correspondence: Dr. Richard J. Glassock, 8 Bethany, Laguna Niguel, CA 92677.Phone: 949-388-8885; Fax: 949-388-8882; E-mail: [email protected]

Copyright © 2010 by the American Society of Nephrology ISSN: 1555-9041/506–1141

activity that induces resistance to antibiotics (1). Although thisgroup of organisms may be reported as sensitive to cephalo-sporins upon initial testing, they can quickly undergo geneticmutation with selection pressure for �-lactamase–producingmutants and become resistant to this class of antibiotic. Bacteriaincluded in the SPICE category include

SerratiaPseudomonas/ProvidenciaIndole-positive Proteus/Acinetobacter/MorganellaCitrobacterEnterobacterThe initial response of the patient’s peritonitis to the cepha-

losporin-based therapy speaks to the initial sensitivity of theAcinetobacter to these antibiotics; however, by the 10th day oftreatment, the peritonitis relapsed because of the resistance thatsupervened. Fortunately, the organism remained sensitive toaminoglycoside, his antibiotics were adjusted accordingly, andthe peritonitis was cured. For serious infections caused bySPICE or extended-spectrum �-lactamase organisms, the anti-biotics of choice are the carbapenems (2).

The incidence of inducible resistance to antibiotics varies indifferent parts of the world and these bacteria may also possessfactors that confer resistance to other antibiotics such as thefluoroquinolones and aminoglycosides (3). It is important to beaware of this activity in the SPICE group of bacteria. Otherwise,for example, the peritonitis in the patient discussed may havebeen considered resistant to treatment and his PD catheterremoved. Several methods are available to detect extended-spectrum �-lactamase activity, but they may be confounded byother factors that contribute to �-lactam resistance, such asproduction of Amp-C �-lactamase by Enterobacteriaceae (4). Forthis and many other reasons, it is helpful to have an infectiousdisease specialist with an interest in PD peritonitis work inconjunction with a PD program.

Fungal peritonitis is a very serious complication in PD and isassociated with technique failure and death (5). Patients whoare especially at risk for this type of peritonitis include theelderly, patients with diabetes, and those who are receiving

immunosuppressive drugs. Perhaps the greatest risk for yeastor fungal peritonitis is the use of broad-spectrum antibiotics,especially when instilled in the peritoneal cavity (6). It is pos-tulated that the antibiotics disturb the usual balance betweenbacteria and fungi within the bowel lumen, allowing for over-growth of the fungi. Consequently, the extra burden of intralu-minal fungi leads to migration of these organisms across thebowel wall and into the peritoneal cavity. Although there areanecdotal reports of eradication of these infections with anti-fungal agents, this is a rare event, and, in most cases, thecatheter must be removed to treat the infection (7). After aperiod off PD, usually �6 weeks, another catheter can be re-inserted; however, fungal peritonitis is often associated withthe formation of intraperitoneal adhesions that may prevent thesuccessful resumption of PD. Unfortunately, it is difficult topredict who will develop adhesions, and they cannot be im-aged, so it is impossible to know whether another catheter canbe inserted successfully until the time of the procedure. The useof antifungal prophylaxis concurrent with broad-spectrum an-tibiotics has been advocated to reduce the fungal overgrowthand thus reduce the risk for a secondary fungal peritonitis.Results of studies using this approach have been variable, butin centers where there is a higher baseline rate of fungal peri-tonitis, the use of prophylaxis seems to reduce this complica-tion (8,9). Given that a regimen such as oral mycostatin isassociated with few complications, it may be worthwhile toco-administer oral mycostatin at the same time as the patient istaking antibiotics, given the poor outcomes that are associatedwith fungal peritonitis. Although answer A addresses the re-duction in risk for fungal peritonitis because of the prophylaxis,it is an overstatement to say that this complication is “unlikely”because of it. Certainly with a “relapse” during antibiotic ther-apy, fungal peritonitis must be considered a possibility. An-swer B is not likely. First, the time to relapse in this case isparticularly short for someone who stopped taking antibiotic.Second, it is underappreciated how painful peritonitis is (10),and so a home dialysis patient, who already undergoes dialysisautonomously, will be motivated to continue the antibiotictherapy.

Icodextrin is a starch-based polymer that is used as an alter-native to dextrose solutions for ultrafiltration in PD. The dex-trins of dispersed molecular weight exert an oncotic pressureacross the peritoneal capillary network, resulting in slow butsustained ultrafiltration. In patients who are rapid transportersand have early dissipation of the glucose-based osmotic gradi-ent and loss of ultrafiltration over the long dialysis dwells,icodextrin has proved very helpful. Adverse effects are mini-mal, although skin rashes have been reported as a reaction tothis solution (11). Several years ago, several cases of culture-negative peritonitis were described with the use of icodextrin.This peritoneal reaction was found to be related to contamina-tion of the solution by peptidoglycans that originated in thestarch product, and modification in the production of thissolution has resulted in a reduction in this complication (12).That is why answer D is not the best choice. In addition, thechemical peritonitis that is associated with the peptidoglycans

Figure 1. Answers from the membership, question 1.

1142 Clinical Journal of the American Society of Nephrology Clin J Am Soc Nephrol 5: 1141–1160, 2010

typically manifests with a lower peritoneal cell count with lessneutrophilic predominance.

Finally, with instillation of high dosages of antibiotics intothe peritoneal cavity, there will be equilibration of these agentswith the blood compartment. Re-diffusion of the antibiotic intothe peritoneal cavity with subsequent PD exchanges will bringmore antibiotic into the peritoneal fluid; however, the principalbacterial killing occurs with the very high dosages of antibioticthat is usually given on a daily basis in the treatment of PDperitonitis (13); therefore, answer E, which suggests that bloodconcentration of antibiotic (rather than intraperitoneal concen-tration) is important in treating the peritonitis, is not correct.

Case 2: Joanne M. BargmanA 55-year-old right-handed woman with type 2 diabetes andprogressive diabetic nephropathy has been followed in a mul-tidisciplinary predialysis clinic for 2 years. She has receivededucation on options for renal replacement therapy. There areno candidates to donate a kidney, and she declines home PD.She undergoes left radiocephalic fistula creation, but the fistulafails to mature. She is assessed for fistula creation on the rightarm, but venous studies demonstrate in the right innominatevein a stenosis that is believed to be a sequela of a previouscentral line during an intensive care unit admission for urosep-sis.

While she is waiting to be reassessed by the vascular sur-geon, she has another episode of urosepsis and develops symp-tomatic uremia and volume overload. She is admitted to hos-pital, and a tunneled cuffed catheter is placed via the leftinternal jugular vein. She is started on hemodialysis (HD) threetimes a week.

After 1 month of HD, there is no evidence of return of renalfunction. She is reluctant to proceed with creation of anotherfistula. In the sixth week of therapy, she develops fever andchills on dialysis. There is no evidence of infection at the exitsite and no hemodynamic compromise. There is no other ob-vious source of infection. A presumptive diagnosis of linesepsis is made, and she is treated as an outpatient with intra-venous cefazolin and gentamicin. Blood cultures grow coagu-lase-negative Staphylococcus that is sensitive to cephalosporins.She is prescribed cefazolin at each HD session for 3 weeks.Three days later at the HD unit, she has had no fever and doesnot develop fever or chills during the dialysis run.

Question 2At this point, which ONE of the following is the BEST approachto her subsequent treatment (Figure 2)?

A. Continue the intravenous cefazolin for 3 weeks total, andchange the dialysis line over a guidewire.

B. Discontinue the intravenous cefazolin after 1 week, andswitch to oral therapy for 2 weeks.

C. Continue the intravenous cefazolin for 3 weeks total, mon-itor the exit site, but change the line only if there is evidenceof infection at the exit site.

D. Continue the intravenous cefazolin for 3 weeks, and re-sitethe tunneled venous catheter to the femoral vein.

E. Continue the intravenous cefazolin for 3 weeks, do notchange or re-site the tunneled internal jugular line, andinstitute an antibiotic lock.

Discussion of Case 2 (Question 2)The correct answer is A: Continue the intravenous cefazolin for3 weeks total, and change the dialysis line over a guidewire.The use of tunneled subclavian catheters and, more recently,tunneled internal jugular catheters, has made it possible to haveimmediate venous access for urgent or emergent HD and al-lows the patient to leave hospital and await a more permanentvascular access. Unfortunately, the permanent (and superior)form of vascular access, such as an arteriovenous fistula, oftennever is established. First, the patient may become comfortablewith the internal jugular line, both because it avoids needlestick and because of a reluctance to undergo more procedures.Second, the patient may agree to creation of an arteriovenousfistula but that surgery is not successful or the fistula is createdbut does not develop sufficiently to support the HD bloodflows. According to recent data from the US Renal Data System,a majority of patients start HD with “temporary” venous ac-cess, and even many months later, half or more of these patientsstill have a catheter.

Catheter-related bacteremia (CRB) is a frequent complicationof indwelling HD catheters and is associated with a number ofserious complications, including septicemia, hospitalization,metastatic infection, and death. Indeed, the increased risk formortality that results from an episode of CRB does not dissipatewith treatment of infection but instead is associated with anongoing increased death risk for several years (14).

CRB that is associated with ongoing septic symptoms, in-cluding fever and hypotension, is usually treated with antibi-otics, systemic support, and removal of the dialysis catheter.Similarly, the catheter is removed when there is CRB in asso-ciation with infection at the exit site. What is unclear is whetherthe catheter has to be removed when there is an “uncompli-cated” CRB—that is, unassociated with hemodynamic compro-mise or exit-site infection.


Clin J Am Soc Nephrol 5: 1141–1160, 2010 Nephrology Quiz and Questionnaire: 2009 1143

Unfortunately, most studies to date have suggested that an-tibiotic therapy alone without removal or exchange of the HDcatheter is associated with an unacceptable rate of relapse of thebacteremia. Only one third of catheters could be “salvaged”with this approach, and, in the majority, the infection recurredsuch that the catheter eventually had to be removed (15,16).Moreover, there seems to be a higher incidence of metastaticinfection compared with those who undergo immediate re-moval of the infected line (17,18). A recent study from theUnited Kingdom reported a salvage rate in two thirds of bac-teremias, but this entailed 6 weeks of parenteral antibiotics,including the use of two antibiotics for Gram-positive organ-isms (19). This kind of prolonged, intensive regimen may in-crease the chances of antibiotic-associated adverse effects andperhaps bacterial resistance. Because catheter salvage with an-tibiotics alone for 3 weeks will not be successful in the majorityof cases, answers B and C (switch to oral antibiotics) are not thebest choices.

If a more definitive approach is to remove the dialysis cath-eter, then this can be accomplished in two ways: The firstoption is to remove the catheter, leave the patient withoutaccess for a day or two, and then re-insert a new catheter at theoriginal or at another site. This approach subjects the patients totwo procedures. Furthermore, in those with tenuous vascularaccess, there is a possibility that venous access will not bere-established at the re-insertion of the catheter. Patients mayalso have to be hospitalized to expedite the two interventions.Another approach is to remove the catheter but replace it overa guidewire at the same procedure (20). This both avoids an-other intervention and preserves the same venous access. Theguidewire-exchange approach has been demonstrated to be asefficacious as the two-step procedure (21–23) and does notseem to leave the patient more vulnerable to metastatic infec-tion (23). More recently, however, Mokrzycki et al. (24) sug-gested that the guidewire exchange may not be as successful forCRB that is caused by Staphylococcus aureus. In the case inquestion, the causative organism was coagulase-negativeStaphylococcus, so answer A, guidewire exchange and 3 weeksof parenteral antibiotics, is correct. Option D is partially correct,insofar as the catheter could be removed and re-sited; however,this patient had limited vascular access, and re-siting a catheterto the femoral vein would be less preferable and associatedwith a higher risk for complications.

The final consideration is alluded to in option E, whether thecatheter could be kept in situ without a guidewire exchange byusing an antibiotic lock in the catheter lumen to kill the organ-isms in the bacterial biofilm. Very high concentrations of anti-biotic are instilled into each port at the end of each HD sessionand left there until the beginning of the next session, when theantibiotic solution is aspirated. This approach has salvagedcatheters in two thirds or more of CRB without the need forguidewire exchange or catheter replacement (25,26); however,once again, infection with Staphylococcus aureus seems to beresistant to this approach, with a low salvage rate and anunacceptable complication rate (26,27). In this case of CRBcaused by coagulase-negative Staphylococcus, however, option Eis an acceptable alternative to guidewire exchange. Because it is

a relatively newer procedure, however, I am reserving judg-ment and suggest that option A is the better one. Of course,from the vantage of the patient, an antibiotic lock would bepreferable to a line change.

Case 3: Biff F. PalmerA 33-year-old black woman is admitted with right flank painradiating to the groin in association with gross hematuria. Herhistory is noteworthy for one previous episode of nephrolithi-asis 6 months before. The patient works as a fashion model andas such has always been concerned about her body weight. Sheadmits to use of diuretics in the past but denies recent use ofdiuretic, laxatives, or vomiting. Physical examination shows aBP of 122/78 mmHg with no orthostatic changes. The remain-der of the examination is normal. Laboratory data are given inTable 1.

Question 3Which ONE of the following can BEST account for the clinicalfindings in this patient (Figure 3)?

A. Surreptitious vomitingB. Surreptitious laxative abuseC. Bartter syndromeD. Sjogren syndromeE. Surreptitious diuretic abuse

Discussion of Case 3 (Question 3)Surreptitious laxative abuse (B) is the best explanation for thefindings in this case. The prevalence of this disorder has beenestimated to be between 4 and 26% of patients with chronic

Table 1. Laboratory data for case 3

Parameter Value

Creatinine (mg/dl) 1.1BUN (mg/dl) 14Serum electrolytes

(mEq/L)Na� 139K� 2.3Cl� 92HCO3 34

Urine electrolytes(mEq/L):Na� 10K� 15Cl� 80

Urinalysis and urineculture

Specific gravity 1.024, pH 6.8,� blood on dipstick, 20RBC/hpf, 5 to 10 WBC/hpf; urine culture: nogrowth

Stone analysis Ammonium urate

BUN, blood urea nitrogen; hpf, high-power field; RBC, redblood cells; WBC, white blood cells.


diarrhea (28). Although one typically associates diarrhea withthe development of a normal anion gap metabolic acidosis,hypokalemic metabolic alkalosis can be the dominant acid-basedisturbance in these patients.

Acid-base disturbances that result from diarrhea can varydepending on the site of origin of the diarrhea, whether thediarrhea is secretory or osmotic, the duration of the disorder,and the degree of K� deficiency (29). Under normal circum-stances, stool electrolyte content is such that the sum of Na�

and K� exceeds the concentration of Cl�. The resultant aniongap can be accounted for by stool HCO3 and a variety oforganic anions, many of which are derived from bacterial me-tabolism of dietary carbohydrates. These organic anions areabsorbed and subsequently metabolized into HCO3 and there-fore represent a potential source of alkali. In the setting of acutediarrhea, particularly of small bowel origin, there is a signifi-cant loss of alkali from the body in the form of both HCO3 andpotential HCO3 as a result of loss of organic acids. Despite thedevelopment of systemic acidosis, the stool pH is typicallyacidic as a result of the high concentration of these acids.

Surreptitious laxative abuse typically involves drugs that arestimulants of the colon. Because colonic fluid has a high K�

content, patients who abuse these drugs tend to develop sig-nificant total body K� depletion (30). Hypokalemia can con-tribute to the development of metabolic alkalosis in severalways. First, the movement of K� from the intracellular toextracellular space in response to K� depletion will be accom-panied by movement of H� into cells, resulting in intracellularacidosis. The decrease in cell pH will serve as a stimulus for H�

secretion in the distal nephron of the kidney. Hypokalemia alsoleads to increased expression of the H�-K�-ATPase in the distalnephron. In the proximal tubule cell, acidification serves as amajor stimulus for increased synthesis of ammonia. The in-crease in availability of ammonia to act as a urinary buffercombined with an increase in H� secretion by the distalnephron leads to the generation of a metabolic alkalosis. Theurinary anion gap is negative in this situation as a result of thelarge increase in urinary NH4Cl excretion. Renal net acid ex-

cretion exceeds the loss of actual or potential base in the stool sothat the net effect is development of metabolic alkalosis.

The large increase in urinary ammonium concentration canpredispose to the development of ammonium urate stones aswas seen in this patient. Dick et al. (31) described nine womenwith laxative abuse complicated by ammonium urate calculi.Measurement of urinary electrolytes in these patients showedlow values for Na� and K� but increased urinary Cl� (negativeurinary anion gap), consistent with increased urinary ammo-nium excretion. Intracellular acidosis as a cause of increasedrenal ammoniagenesis was inferred by the finding of low uri-nary citrate levels because intracellular acidosis stimulatesproximal citrate resorption. The authors postulated the lowurinary Na� concentration that results from mild volume con-traction allows for urate to bind to the abundant ammoniumion and predispose to ammonium urate stone formation.

A similar mechanism may be responsible for endemic am-monium urate bladder stones described in children from third-world countries (32). These patients have an acidogenic dietthat is low in phosphate as a result of the high cereal contentand lack of animal protein intake. Increased ammonia is theprimary buffer for H� secretion, particularly because urinaryphosphate excretion is low as a result of low animal proteinintake. The frequent occurrence of diarrhea predisposes thesepatients to low urinary volumes and low urine Na� concentra-tion. As in patients with laxative abuse, urate in the urine is freeto bind to the high concentrations of ammonium, leading to theformation of ammonium urate calculi (Figure 4).

For years, the most commonly abused laxative was phenol-phthalein. Patients who used this laxative could be detected byalkalinizing a sample of urine or stool and looking for thedevelopment of a strong violet color change. Several years ago,the drug was reclassified by the Food and Drug Administrationso that it is no longer available as an over-the-counter agent.

The two most frequently abused laxatives today are bisaco-dyl and anthraquinones (28). Bisacodyl is the active ingredientin Ex-Lax, Correctol, and Dulcolax. The most commonly usedanthraquinone is senna, which is the active ingredient in Seno-kot, Castoria, and Black Draft. Use of these laxatives can bedetected in either stool or urine samples using thin-layer chro-matography.


Figure 4. Proposed mechanism for ammonium urate renalstone formation in a patient with long-term laxative abuse.


Specimens that are submitted for laxative screening in theUnited States are directed to a single reference laboratory. Inthis regard, Shelton et al. (33) submitted stool and urine samplesthat were taken from normal volunteers in which diarrhea wasinduced by ingestion of either bisacodyl or senna to verify thesensitivity and specificity of the assay used in this referencelaboratory. Interestingly, the tests were reported as negative inall samples of urine and stool taken from the participants withsenna-induced diarrhea. Testing of samples that were takenfrom participants with bisacodyl-induced diarrhea was moreaccurate but had sensitivity of only 73 and 91% and specificityof 91 and 96% for the urine and stool samples, respectively. Thisstudy suggests that testing for laxative abuse as currently prac-ticed can produce misleading results with a high frequency offalse-positive tests for bisacodyl and false-negative results forsenna. It is important for clinicians to be aware of these limi-tations in testing, because they evaluate patients with suspectedlaxative abuse.

Vomiting (A) can certainly present as hypokalemic metabolicalkalosis and should be suspected in a patient with possiblebulimia; however, the urine electrolytes would argue againstthis diagnosis, and vomiting cannot account for the history ofammonium urate nephrolithiasis. Vomiting leads to a contrac-tion of extracellular fluid volume, and loss of gastric acid gen-erates a metabolic alkalosis. While the patient is vomiting, theplasma HCO3 exceeds the tubular maximum for bicarbonateresorption in the proximal tubule, which leads to renal loss ofNaHCO3 (further exacerbating total body salt depletion) andKHCO3 (leading to K� depletion). The volume depletion leadsto an increase in aldosterone secretion, which in the setting ofhigh distal Na� delivery accounts for the renal K� wasting.Typical urinary electrolytes in active vomiting are a urine Cl�

�15 mEq/L, in the presence of a high urine Na�, a high urineK�, and a urine pH of 7 to 8.

Bartter syndrome (C) is also not correct. Although this dis-order is characterized by hypokalemic metabolic alkalosis,urine Na�, K�, and Cl� all are increased. This pattern of urineelectrolytes is also characteristic of active loop and thiazidediuretic use, making choice E incorrect. In addition, Barttersyndrome and diuretic use would not account for the develop-ment of the renal stone disease described in this patient.

The two most common renal manifestations in Sjogren syn-drome are nephrogenic diabetes insipidus and type 1 distalrenal tubular acidosis (RTA). Although nephrolithiasis andnephrocalcinosis are characteristic of patients with type 1 RTA,the stone composition is most commonly calcium phosphate.The type of stone and the lack of a hyperchloremic metabolicacidosis make a diagnosis of Sjogren syndrome untenable (D).

Case 4: Biff F. PalmerA 35-year-old woman is admitted with left flank pain and feverfor 2 days. Physical examination shows a toxic-appearing thinwoman. Vital signs are significant for a temperature of 38.5°C,BP 100/68 mmHg, pulse 110, and respiratory rate of 24. Right-sided costovetebral tenderness is present. An ultrasound of theabdomen shows normal-sized kidneys and no evidence of hy-dronephrosis. Renal function and serum electrolytes on admis-

sion are normal. Right-sided pyelonephritis is diagnosed. Thepatient is treated with intravenous ticarcillin/clavulanate, gen-tamicin, and tetracycline, and the patient’s clinical conditiongradually improves over the next several days. After a 2-weekcourse of parenteral antibiotics, she is discharged on no medi-cations. One week after discharge, the patient presents with thecomplaint of weakness and paresthesias. Physical examinationshows downward beat nystagmus, and carpal pedal spasm iselicited. An electrocardiogram showed prominent U waves andQ-T prolongation. Laboratory data are given in Table 2.

Question 4Which ONE of the following is the MOST likely cause of theelectrolyte abnormalities in this patient (Figure 5)?

A. Complication of ticarcillin/clavulanateB. Surreptitious diuretic useC. Tetracycline nephrotoxicityD. Aminoglycoside nephrotoxicityE. Gitelman syndrome

Discussion of Case 4 (Question 4)Aminoglycoside nephrotoxicity (D) is the correct answer. Thispatient presents with the development of hypokalemic meta-bolic alkalosis with normal BP after a recent hospitalization inwhich she was treated with a variety of antibiotics for pyelo-nephritis. The electrolyte disturbance is accompanied by highnormal values for plasma renin activity and aldosterone. Urinarycalcium is increased, and the patient has hypomagnesemia.Many of the features in this case are consistent with Barttersyndrome, although the abnormalities in this patient are re-

Table 2. Laboratory data for case 4

Parameter Value

Creatinine (mg/dl) 0.9BUN (mg/dl) 14Serum electrolytes (mEq/L)

Na� 139K� 2.3Cl� 92

HCO3 34Urine electrolytes (mEq/L)

Na� 110K� 35Cl� 106

Serum magnesium (mg/dl) 0.9Spot urine Ca2�/creatinine

(mg/mg)0.53

Other testing Plasma renin activity2.4 ng/ml per h(0.8 to 2.5),aldosterone 235ng/dl (35 to 240)

BUN, blood urea nitrogen.


cently acquired as evidenced by the normal serum electrolyteson admission to the hospital.

Bartter syndrome is a hereditary disorder characterized byrenal salt wasting and hypokalemic metabolic alkalosis resem-bling the features of chronic loop diuretic therapy. This diseaseresults from gene defects that lead to decreased NaCl resorp-tion in the thick ascending limb of Henle.

With relevance to this case, an acquired form of Barttersyndrome can develop in association with the administration ofaminoglycoside antibiotics (34–36). Chou et al. (36) describedfour patients who presented with marked paresthesia, muscleweakness, and tetany after gentamicin therapy with total dos-ages ranging from 1.2 to 2.6 g. All four patients developedhypokalemia, metabolic alkalosis, hypomagnesemia with hy-permagnesuria, and hypercalciuria. These abnormalities even-tually resolved over a period of 2 to 6 weeks. A similar Bartter-like syndrome has been described in rats that were givengentamicin. In these animals, administration of the drug leadsto increased urinary excretion of Na�, K�, Ca2�, and Mg2�

accompanied by decreased expression of the Na�-K�-2Cl� co-transporter in the thick ascending limb (37). The biochemicalfindings in patients who have developed this form of nephro-toxicity resemble those seen in patients with gain-of-functionmutations in the calcium-sensing receptor. Because gentamicinis a divalent cation, binding and activation of the calcium-sensing receptor may account for the development of this clin-ical syndrome (38) (Figure 6).

Gitelman syndrome is also characterized by hypokalemicmetabolic alkalosis; however, this diagnosis (E) can be excludedby the normal electrolytes at the time of admission to thehospital as well as the high urinary Ca2� excretion. Hypocal-ciuria is the typical finding in patients with this disorder.

Surreptitious use of loop or thiazide diuretics can be a causeof hypokalemic metabolic alkalosis that is intermittent in natureand cannot be totally excluded in this case; however, there wasno history to suggest that this patient was prone to abuse ofsuch drugs and therefore choice B would not be the best answerto explain the features in this case.

One of the antibiotics used in the treatment of this patientwas ticarcillin. A complication of this drug when given topatients who are volume depleted is the development of hy-pokalemic metabolic alkalosis. The drug is excreted as a Na�

salt and acts as a nonresorbable anion. In the setting of in-creased aldosterone levels, the high distal Na� delivery leads toincreased renal K� excretion. The increase in luminal electro-negativity in the distal nephron also stimulates H� secretion,thus leading to the generation of a metabolic alkalosis. Charac-teristic urine electrolytes in this setting are increased urine Na�

and K�, a low urinary Cl�, and an acid urine pH. As long aspatients are kept euvolemic so that aldosterone levels are sup-pressed, serum electrolytes remain normal when the drug isgiven. The development of the electrolyte abnormalities wellafter being exposed to the drug as well as the urinary electro-lyte pattern in this patient exclude A.

As detailed in a recent review, tetracyclines may enter cells inthe proximal tubule through organic anion transporters fromeither the apical or the basolateral side (38,39). Once inside thecell, these drugs can produce tubular injury by inhibiting ribo-somal protein synthesis. Such injury may result in developmentof a proximal RTA usually associated with Fanconi syndrome.The absence of hypokalemic normal gap metabolic acidosis andother features of proximal tubular dysfunction make C incor-rect.

One last comment about this patient has to do with theneurologic manifestations noted on physical examination. Oneof the clinical manifestation of hypomagnesemia is increasedneuromuscular irritability. In addition, hypomagnesemia is oneof the few causes of downbeat nystagmus, as was seen in thiscase (40,41).

Case 5: Millie SamaniegoA previously healthy 26-year-old white woman presented withfever, vomiting, abdominal cramping, and diarrhea. Threeweeks before this presentation, she noticed bruising over herextremities followed by upper respiratory tract symptoms withsore throat and rhinorrhea. Her husband and her 11-month-oldson had similar respiratory symptoms, and the husband re-ceived a diagnosis of culture-positive streptococcal pharyngitis.

Figure 6. Gentamicin is a divalent cation and therefore has thepotential to bind to the basolateral Ca2�-sensing receptor in thethick limb of Henle. This binding leads to inhibitory effects onthe apical transporters, thereby contributing to a Bartter-likesyndrome.



On presentation, the patient’s initial laboratory abnormalitiesincluded a hemoglobin level of 6.7 g/dl, hematocrit of 18%,platelet count of 19,000/mm3, blood urea nitrogen level of 75mg/dl, and creatinine level of 4.6 mg/dl. Urinalysis showed 3�

protein and 3� blood, and the urinary sediment was abnormalwith �100 red blood cells per high-power field and granularcasts. A kidney biopsy showed diffuse capillary fibrin deposi-tion and segmental staining for fibrin and IgM along the glo-merular basement membrane (GBM), consistent with a diagno-sis of thrombotic microangiopathy (TMA). A disseminatedintravascular coagulation workup was negative. Stool culturesfor Escherichia coli O157:H7, Salmonella, Campylobacter, Shigellaspecies, ova, and parasites were negative. Other relevant testswere a C3 level of 58 mg/dl (normal range 70 to 205) and C4level of 20 (normal range 10 to 60); negative antinuclear anti-body (ANA) and anti-streptolysin O titers; and negative anti-PR3, anti-myeloperoxidase, and anti-GBM antibody levels. HerADAMST-13 activity was 97% (normal range �67) and inhibi-tor �0.4 units (normal range �0.4).

She received a diagnosis of atypical hemolytic uremic syn-drome (aHUS) and was treated aggressively with 41 plasmaexchange sessions, four doses of rituximab, and a single dose ofvincristine without clinical response. She presents to your officefor preemptive transplant evaluation 7 months after the onsetof disease and would like to know what the probability ofdisease recurrence in the transplant is.

Question 5AGiven the clinical presentation of this patient, which ONE off thefollowing statements is MOST appropriate concerning the likeli-hood of recurrence of disease in a renal allograft (Figure 7)?

A. The likelihood of recurrence is low, because the patient hasnonfamilial HUS likely as a result of streptococcal infection.

B. The likelihood of recurrence is high but will decrease withtime; therefore, delaying transplantation for 1 year is appro-priate.

C. Additional testing is necessary to provide an accurate esti-mate of the likelihood of recurrence.

D. Because her likelihood of recurrence is exceedingly high,living-donor transplantation should be avoided and sheshould be listed for a deceased-donor transplant.

Discussion of Case 5 (Question 5A)The most appropriate answer to this question is C: Additionaltesting is necessary to provide an accurate estimate of thelikelihood of recurrence. HUS is characterized by microangio-pathic hemolytic anemia, thrombocytopenia, and acute kidneyinjury. HUS is classified in two large categories: Diarrheal(D�HUS) and nondiarrheal (D�HUS). Microvascular endothe-lial cell injury underlies both forms of this disease and leads tothe loss of the endothelium anticoagulant phenotype, enhancedplatelet consumption and leukocyte trafficking, complementactivation, and disruption of the fibrinolytic pathways (42).

D�HUS more commonly affects children than adults, canpresent in an epidemic manner, and is usually associated witha prodrome of severe bloody diarrhea, hence its name. Endo-thelial cell injury is caused by Shiga toxin–producing bacteriaand can be sporadic, endemic, or epidemic. Escherichia coliO157:H7 strains are responsible for most cases of D�HUS. Thediarrhea in our patient is a red herring and likely represents anonspecific response to acute illness (42,43).

D�HUS, or aHUS, is more frequent in adults, can be sporadicor familial in presentation, and is unrelated to diarrhea. Thepast decade has seen the identification of mutations in thegenes for complement factor H (CFH), complement factor I(CFI), and membrane co-factor protein (MCP; or CD46) aspredisposing factors for the development of D�HUS. Approx-imately 30 to 50% of patients with D�HUS have genetic defectinvolving the complement regulatory proteins (CRPs). A grow-ing number of mutations and polymorphisms that alone or incombination may lead to D�HUS are being identified. Some ofthe less well-characterized genetic defects involve C3 and com-plement factor B (44–48).

CFH is a serum glycoprotein that is synthesized by the liverand regulates the function of the alternative pathway of com-plement in fluid phase and on cellular surfaces. It binds to C3b,accelerates the decay of the C3 convertase, and also acts as aco-factor for CFI. The CFH gene is located on chromosome1q32-q32.1 within a cluster of genes encoding regulatory com-plement components (45). CFI is a serum regulatory serineprotease that is predominantly synthesized by the liver as asingle-chain precursor, the gene of which is located on chro-mosome 4q25. MCP is a widely distributed C3b/C4b-bindingcell surface glycoprotein that serves as an inhibitor of comple-ment activation via the classical and alternative pathways onhost cells. The genes for MCP are tightly clustered on chromo-some 1 at q3.2 (46).

Deficiency or dysfunction of CRPs leads to complement-mediated endothelial cell injury in the setting of unregulatedactivity of the C3 and C5 convertases that leads to the produc-tion of proinflammatory complement split products (C3a, iC3b,C3dg, and C5a) and the membrane attack complex (C5bthrough C9) (45).

Kidney transplantation in patients with HUS is associatedwith a variable rate of disease recurrence in the transplantedFigure 7. Answers from the membership, question 5A.


graft, yet when recurrence occurs, it usually results in the lossof the transplant. Thus, an accurate diagnosis of the cause ofHUS must be pursued before transplantation. Table 3 showsthe various rates of HUS recurrence on the basis of its differentcauses (43,45,49,50).

The diagnostic workup in this patient effectively ruled outD�HUS, because stool cultures for Shiga toxin–producing bac-teria were negative, whereas negative lupus serologies andADAMST-13 inhibitor and normal ADAMST-13 activity ruledout sporadic forms of D-HUS such as systemic lupus erythem-atosus (SLE) and familial or sporadic thrombotic thrombocyto-penic purpura (51,52). Notably absent in the assessment of thispatient, however, was the evaluation for familial forms ofD-HUS or inhibitors of CRPs (CFH, CFI, MCH, and MCP au-toantibodies) (44).

Several findings in this patient suggest deficiency or dysfunc-tion of CRPs as the cause of D�HUS, including young age andpersistently low levels of C3 with normal C4 levels. In almostall cases of D�HUS as a result of mutations in CFH and CFI, C4levels are normal and C3 levels are low, whereas in MCPmutations, C4 and C3 levels are normal. Because of low sensi-tivity, the presence of normal C3 levels does not exclude mu-tations of CRP genes (44,45).

Because patients with CRP deficiency or dysfunction lack aclassical clinical phenotype, this diagnosis is often missed(46,49). Only in cases in which clinical suspicion prompts thetesting of serum activity and levels of CRPs as well as geno-typing can accurate diagnosis be reached.

Choice A—the likelihood of recurrence is low because thepatient has nonfamilial HUS likely as a result of streptococcalinfection—is the wrong answer. In patients with HUS, a historyof recurrent streptococcal infections or infections with otherencapsulated microorganisms (e.g., Neisseria meningitidis, Hae-mophilus influenzae) suggests a familial etiology, especially CFHor CFI deficiency. In these patients, functional C3 deficiency asa result of uncontrolled activation of the alternative pathway ofcomplement leads to deficient opsonization and phagocytosisof encapsulated organisms and hence infection (46). As shownin Table 3, CFH and CFI deficiencies are associated with highrecurrence of disease in kidney transplants and graft loss.

Choice B—the likelihood of recurrence is high but will de-

crease with time; therefore, delaying transplantation for 1 yearis appropriate—is also incorrect. In patients with D�HUS orD�HUS as a result of MCP deficiency or drug-induced injury(e.g., ticlopidine, valacyclovir, clopidrogel), recurrence is negli-gible and kidney transplantation need not to be delayed(43,45,50).

In contrast, in patients with acquired (i.e., autoantibodies orinhibitors) or hereditary deficiencies of CRPs, the risk for re-currence persists throughout the life of the individual unlessthe basic defect is corrected. Prevention of disease recurrenceand correction of CFH or CFI deficiency can be accomplishedwith combined kidney-liver transplantation (46,53). Althoughthe initial three reports that described this modality for CFH-associated HUS had poor outcome, more recent reports inwhich combined kidney-liver transplantation has been per-formed successfully in combination with pretransplantationplasma exchange have been described (53).

Current recommendations for combined kidney-liver trans-plantation include CFH and CFI mutations, �10% normal CFHlevels in plasma, patients with identified mutations of CFH andCFI genes with recurrence after isolated kidney transplantation, orpatients who have a family member with the same mutation andrecurrence of HUS after isolated kidney transplantation (53).

The correct answer is D: Because her likelihood of recurrenceis exceedingly high, living-donor transplantation should beavoided and she should be listed for a deceased-donor trans-plant. This choice is controversial. Similar to option B, thechoice of pursuing or avoiding transplantation or the use of adeceased donor vìs a vìs a living donor depends on the cause ofHUS and the likelihood of recurrence. In a meta-analysis of 10selected studies in 159 grafts of 127 patients with a well-docu-mented history of HUS in native kidneys and biopsy-provenTMA in the transplanted kidney, living-donor transplantationwas associated with an increased risk for recurrence; however,the risk for recurrence in living-related versus -unrelated kidneytransplants was not analyzed (54).

Patients with D�HUS or D�HUS as a result of drug toxicityshould be offered living-donor transplantation. In patients withD�HUS as a result of CRP deficiencies or dysfunction, living-unrelated donor transplantation should be discouraged giventhe high likelihood of recurrence and recurrence-related graft

Table 3. Rates of recurrence of HUS according to cause (46,47,50,53)

HUS in Native Kidneys Relative Risk of Recurrence in KTx (%)

Postdiarrheal HUS (D�HUS) NegligibleNondiarrheal HUS (D�HUS) sporadic or familial forms

CFH mutation 80CFI mutation 80 to 100Idiopathic (unidentified genetic defect?) 30 to 50MCP mutation 0 to 20CFH autoantibodies 0C3 and CFB deficiency ?drugs, pregnancy, invasive S. pneumoniae infection Negligible

KTx, kidney transplantation.


loss. Patients with MCP deficiency or anti-CFH autoantibodies,however, should be considered for living-unrelated kidneytransplantation. MCP has a high level of expression in kidneytissue, and transplantation with a living-donor kidney withnormal (wild-type) MCP expression results in the cure of thekidney disease. In patients with CFH autoantibodies, antibody-depleting strategies in conjunction with isolated kidney trans-plantation have been successful (46,50,53).

Many centers do not recommend living-related transplanta-tion because of the risk for recurrence in the recipient and of denovo disease in the donor. In four reported cases, the donorswent on to develop HUS within 1 year of donation. Genotypingof the donor and recipient should be undertaken when living-related donation is to be considered. This will not prevent therisk for the donor in those with an unknown genetic basis(46,50,53). Transplantation options for patients with aHUS areshown in Figure 8.

One year after her first visit to your clinic, the patient receiveda zero-antigen mismatch deceased-donor kidney transplant. Theimmunosuppression consisted of alemtuzumab induction andmaintenance therapy with prednisone, mycophenolate mofetil,and tacrolimus. She had excellent graft function initially with acreatinine level of 1.1 mg/dl on discharge but on day 30 aftertransplantation was admitted with a rise in serum creatinine to1.9 mg/dl. A transplant biopsy showed TMA with many of the19 glomeruli containing fibrin thrombi in a segmental distribu-tion. C4d staining was negative, and the tacrolimus troughlevel was 6 ng/ml. Further testing showed complement C3 of70 (normal range 88 to 201) and C4 of 23 (normal range 16 to 47)and ADAMST-13 activity of 94% (normal �67%) and with

quantitative factor H level of 244.9 �g/ml (normal range 160 to412).

Question 5BWhich ONE of the following choices would MOST likely con-firm the correct diagnosis (Figure 9)?

A. Response to plasma exchangeB. Donor-specific antibody (DSA) testingC. Double-stranded DNA (dsDNA) antibodiesD. Factor I and factor H genotypingE. Discontinuation of calcineurin inhibitor (CNI)

Discussion of Case 5 (Question 5B)The correct answer is D: Factor I and factor H genotyping. Thecurrent evidence suggests that all patients who have D�HUSand are being considered for kidney transplantation shouldundergo screening for mutations in CRPs. An initial screeningshould test protein levels (either serum levels or surface expres-sion). This offers a rapid mechanism to identify the genesinvolved (44,53).

In patients with normal levels of CRPs, genetic screeningshould be performed on the basis of frequency of mutation(CFH approximately 30%; MCP approximately 10%; CFI 2 to5%). The exons in which CRP gene mutations cluster have beenidentified, and by screening these regions first, cost and detec-tion time can be minimized (44,53). The patient presented herewas found to be heterozygous for a novel missense mutation,Y369S, in CFI (55).

Choice A—response to plasma exchange—is incorrect. Re-cent guidelines recommended the use of empiric plasma ther-apy in all forms of D�HUS within 24 hours of diagnosis (53).This is in contrast to previous guidelines in which the use ofplasma exchange was considered a grade C, level IV recom-mendation given the lack of conclusive evidence of improve-ment in outcomes (42).

Choice B—DSA testing—would not confirm the cause of thispatient’s disease. Although this patient may have been sensi-tized against HLA antigens after receiving multiple sessions of

Figure 8. Therapeutic options for aHUS. IF, factor I; BF, factor B;C3, complement protein 3; KTx, kidney transplantation; SKL,simultaneous kidney-liver transplant; Eculizumab, humanizedmAb that functions as a complement inhibitor by blockingcleavage of C5 into C5a and C5b and decreasing formation ofmembrane attack complex. Figure 9. Answers from the membership, question 5B.


plasma exchange, C4 staining in the biopsy was negative, there-fore making the diagnosis of antibody-mediated rejection(AMR) less likely (56). It must be noted that fresh-frozenplasma has been known to contain anti-HLA antibodies thatcan lead to passive sensitization.

Choice C—dsDNA antibodies—is also incorrect. Althoughactive lupus can have a similar clinical presentation to D�HUS,particularly in patients with antiphospholipid antibody syn-drome, this patient does not have systemic evidence of lupusactivity (42). In lupus, both C3 and C4 levels are reduced, theresult of complement activation by autoantibodies via the clas-sical pathway.

Choice E—discontinuation of CNI—would not lead to thecorrect cause of this patient’s kidney disease. CNIs have beenidentified as a cause of drug-induced HUS since the earlystages of their use in clinical transplantation. Recent studieshave now reported that some of the cases that were diagnosedas being CNI related may have actually been caused by AMR,or ADAMST-13 inhibitors (57–59). The recently publishedguidelines from the aHUS Consensus Study Group make nospecific recommendations about use or avoidance of CNIs. Theguidelines state that D�HUS is not considered per se a specificcontraindication to treatment with CNIs and that initial immu-nosuppression with mammalian target of rapamycin inhibitorsshould not be encouraged (53).

Case 6: Millie SamaniegoA 55-year-old multiparous woman with type 2 diabetes re-

ceived a standard-criteria deceased-donor kidney transplantfrom a 20-year-old donor with a cold ischemic time of 6 hours.Her class I and class II flow cytometry panel-reactive antibodies(PRA) were 65 and 80%, respectively. A donor-specific flowcross-match was negative.

Her immunosuppressive regimen consisted of alemtuzumabinduction and maintenance therapy with cyclosporine, myco-phenolate mofetil, and prednisone. Although urine productionwas noted after the vascular anastomosis was completed, theurine output decreased within the first 12 hours after transplan-tation and her blood urea nitrogen and creatinine failed todecrease. A renal transplant ultrasound showed adequateblood flow in the renal transplant artery and vein and a resis-tive index of 1.0. On day 2 after transplantation, the plateletcount was noted to fall from 200,000 to 90,000/mm3, and herhemoglobin decreased from 11 to 8.5 g/dl. A repeat flow cy-tometry cross-match was negative.

Question 6AConcerning the cause of this patient’s transplant dysfunction, whichONE of the following statements is MOST correct (Figure 10)?

A. Delayed graft function (DGF) is likely given the prolongedcold ischemic time.

B. CNI-related TMA is the most likely diagnosis.C. Antibody testing using single-antigen bead flow cytometry

should be performed emergently.D. Observant approach is adequate because this presentation is

consistent with alemtuzumab-related side effects.

Discussion of Case 6 (Question 6A)The correct answer is choice C: Antibody testing using single-antigen bead flow cytometry should be performed emergently.The patient has been sensitized to HLA antigens through mul-tiple pregnancies. She is sensitized against class I HLA mole-cules (i.e., PRA 20 to 79%) and highly sensitized against class IIHLA antigens (i.e., PRA �80%) and, accordingly, has a highimmunologic risk for both T cell–mediated rejection and AMR.Patients as the one discussed with high level of HLA sensitiza-tion are likely to develop an anamnestic DSA response afterreintroduction of antigen in the form of a transplant. In suchindividuals, even if solid-phase assays such as flow-cytometrycross-match are negative, low levels of DSA can be missed andmore sensitive solid-phase assays such as single-antigen beadLuminex flow cytometry are usually required (60,61).

Choice A—DGF is likely given the prolonged cold ischemictime—is incorrect. This patient received a deceased-donortransplant from a young standard-criteria donor and a shortcold ischemia time—all factors associated with a low risk forDGF (62,63). Although the risk for DGF increases in donorswho are older than 13 years, the donor age that is associatedwith a higher risk for DGF is �50 years. Although the risk forDGF increases with cold ischemia time �12 hours, cold isch-emia times �36 (62) or �40 hours (64) are associated with thehighest risk.

Choice B—CNI-related TMA is the most likely diagnosis—isnot a likely cause in this patient’s presentation. This patient hasclinical features suggestive of TMA: Acute anemia and throm-bocytopenia in the setting of transplant dysfunction and re-duced urine output. Although CNIs are a recognized cause ofTMA, the onset of TMA is earlier than expected—usually be-yond day 4 after transplantation—although it can be highlyvariable with a range of 4 to 2190 days after transplantation(65). Furthermore, severe forms of AMR can lead to glomerularfibrinoid thrombosis (56), and some patients can have a TMA-like syndrome.

Choice D—observant approach is adequate because this pre-sentation is consistent with alemtuzumab-related side ef-

Figure 10. Answers from the membership, question 6A.


fects—is a red herring. Alemtuzumab is an effective depletinghumanized mAb directed against CD52—a surface marker ofunknown function that is densely expressed in T and B lym-phocytes, monocytes/macrophages, and natural killer cells. Asopposed to other depletional biologics, alemtuzumab is notassociated with anemia or thrombocytopenia, yet, in some pa-tients, the effect of alemtuzumab on CD52—a glycosylphos-phatidylinositol-anchored protein—translates to other glyco-sylphosphatidylinositol proteins such as the CRPs CD55 andCD59. The dysfunction of CRPs results in complement-depen-dent intravascular hemolysis and thrombocytopenia, and casereports of HUS-like syndrome and TMA in alemtuzumab-treatedpatients have been published (66,67). Regardless of its cause, TMAin native or transplanted kidneys is an emergency, and observantmanagement is not indicated (42).

Single-antigen bead flow cytometry testing showed high lev-els of DSAs against class II antigen DR7, and a kidney trans-plant biopsy confirmed the presence of DSA. The patient re-sponded favorably to aggressive therapy with plasmapheresis,intravenous gammaglobulin, and intravenous steroids and wasdischarged 2 weeks later with a serum creatinine level of 1.4mg/dl. At month 7 after transplantation, she presents to theclinic with a serum creatinine level of 2.5 mg/dl (comparedwith 1.8 mg/dl the previous month) and a urine protein-to-creatinine ratio of 3.5 (compared with 1.0 the previous month).

Question 6BWhich ONE of the following choices is the MOST likely diag-nosis for her proteinuria (Figure 11)?

A. De novo membranous nephropathyB. Recurrent diabetic nephropathyC. Transplant glomerulopathy (TG)D. De novo FSGSE. Acute T cell–mediated rejection

Discussion of Case 6 (Question 6B)The correct choice is C: Transplant glomerulopathy. TG is acondition that is associated with poor outcome and is charac-

terized by duplication of the GBMs, mesangial matrix expan-sion, and mesangial cell interposition (Figure 12). Originallyclassified as a variant of chronic allograft nephropathy of un-known cause, TG is now recognized with increased frequencyin patients with a history of AMR and is also associated withdeposition of the complement split product C4d, suggestingthat TG may be one manifestation of AMR (68,69). Gloor et al.(70) reported a cumulative incidence of TG at 5 years of 20%and a strong association with anti-HLA antibodies especiallyanti–class II, with the risk increasing when the antibodies weredonor specific. Approximately 60% of patients with TG haveproteinuria �500 mg/d at the time of diagnosis, and, withdisease progression, patients can develop nephrosis, like thepatient described here. Per each 1-g increase in proteinuria, thehazard ratio of death-censored graft survival is 1.56 (95% con-fidence interval 1.3 to 1.8; P � 0.0001) (68,70).

The remaining choices are incorrect. Although de novo mem-branous nephropathy, de novo FSGS, and recurrent diabeticnephropathy can result in nephrotic-range proteinuria, thesediseases usually present late in the natural history of kidneytransplantation. De novo membranous nephropathy occurs ap-proximately 49.27 � 32.71 months after transplantation, with acumulative incidence of 5.3% at 8 years after transplantation,and 62% of patients have nephrosis at the time of diagnosis. Denovo FSGS was observed in 30% of kidney transplant recipients

Figure 11. Answers from the membership, question 6B.

Figure 12. Transplant glomerulopathy. (A) Global and severeduplication of capillary walls with minimal, segmental mesan-gial expansion (silver-stained section). (B) Mesangial prolifera-tion, segmental endocapillary proliferation, cellular interposi-tion, and global duplication of capillary walls (periodic acid-Schiff–stained section). (C) Extensive remodeling of the GBMwith extensive reduplication of the GBM (electron microscopy).(D) C4d-stained section in a biopsy with chronic active AMRwith positive peritubular capillaries and global glomerular cap-illary wall staining. Magnification, �400.


during a mean follow-up of 57 months, and 24% of patientsexhibited nephrotic syndrome at the time of diagnosis (71).Virtually 100% of patients with type 2 diabetes will developrecurrence of diabetic nephropathy in the kidney transplantwith an average time to onset of de novo diabetic nephropathyof 10 years (72). Finally, patients with acute T cell–mediatedrejection usually present with nonproteinuric or non-nephroticacute kidney transplant dysfunction. Of note, TG can be T cellmediated, yet TG is a chronic, not an acute, histologic or clinicalcause of transplant dysfunction. That this patient had receiveda diagnosis of AMR early in the course of her transplant makesTG the most likely diagnosis, decreasing the likelihood of theother options.

Case 7: Fernando C. FervenzaIn February 2009, a 64-year-old white woman was evaluated fornephrotic syndrome. Serum creatinine level was 1.6 mg/dl andproteinuria was 11 g/24 h. Tests for hepatitis B and C, cryo-globulins, serum protein electrophoresis, ANCA, and comple-ment levels were either negative or within normal range. ANAtest was 1:80. A renal biopsy showed a membranoproliferativeglomerulonephritis (MPGN) pattern of injury on light micros-copy (Figure 13). On immunofluorescence, there was granularcapillary wall and mesangial staining for IgG (3�), IgM (2�),C1q (1�), C3 (3�), � (3�), and � (trace) but no IgA (Figure 14).Therapy with an angiotensin-converting enzyme inhibitor(ACEI), aspirin, dipyridamole, and prednisone at 60 mg/d wasstarted with the dosage tapered during the subsequent 3months. Despite the treatment, renal function continued todeteriorate, and on June 21, serum creatinine had increased to4.2 mg/dl. She was then referred for further evaluation and a

second opinion. On physical examination, BP was 139/82mmHg, and, apart from peripheral edema, the physical exam-ination was unremarkable.

Laboratory evaluation showed hemoglobin level of 11.7 g/dl,leukocytes of 15.1 � 109/L, platelet count of 356 � 109/L,albumin level of 2.3 g/dl, and serum creatinine level of 4.5

Figure 13. MPGN. The glomerulus shows mesangial expansionwith increase in mesangial matrix and cellularity, mostly as aresult of mononuclear cells, as well as endocapillary prolifera-tion. Capillary walls are thickened, and many loops show sub-endothelial expansion and new basement membrane forma-tion, resulting in double contours and lobular accentuation ofthe glomerular tuft. Extracapillary proliferation, resulting in theformation of a small cellular crescent, is also present (silverstain). Magnification, �400.

Figure 14. Immunofluorescence microscopy. (A and B) Granu-lar staining for IgG (A) and � (B) along the capillary walls. (C) �light chain staining is negative.


mg/dl. Urinalysis showed �100 red blood cells per high-powerfield, �25% dysmorphic, four to 10 white blood cells per high-power field, and a predictive 24-hour urine protein excretion of17 g by urine protein-creatinine ratio. Serum protein electrophore-sis found no monoclonal protein, but immunofixation revealed alow-level monoclonal IgM � plus a monoclonal IgG �. Free � lightchain was 4 mg/dl (0.33 to 1.95), free � light chain was 5.65 mg/dl(0.57 to 2.63), and �-� ratio was 0.7 (0.26 to 1.65). Serum C3 and C4complement levels were normal. An anti-dsDNA antibody wasnegative. A repeat renal biopsy is performed.

Question 7Which ONE of the following is the MOST likely diagnosis(Figure 15)?

A. Necrotizing and crescentic glomerulonephritis, pauci-im-mune

B. Cryoglobulinemic glomerulonephritisC. MPGN secondary to a monoclonal gammopathyD. C1q nephropathyE. Diffuse proliferative lupus nephritis (class IV)

Discussion of Case 7 (Question 7)The correct answer is C. MPGN, or mesangiocapillary glomer-ulonephritis, refers to a specific histologic pattern of glomerularinjury characterized by massive mesangial hypercellularity,mesangial matrix expansion, and thickening of the GBM withthe appearance of “double contours.” The duplicated or splitbasement membranes is the result of new basement membraneformation caused by the interposition of the mesangial cell andmesangial matrix along the subendothelial side of the laminadensa. The proliferation in the mesangial region and mesangialmatrix expansion often has a lobular appearance. MPGN can beidiopathic or secondary to a variety of diseases (Table 4). Sys-temic conditions that are associated with MPGN include auto-immune diseases (e.g., SLE) and chronic infections (e.g., hepa-titis C). Less widely known, however, is the association ofMPGN with monoclonal gammopathy. Monoclonal gammopa-thy is defined as an excessive production of an Ig or its subunits

that arises from a clonal proliferation of plasma cells or Blymphocytes. The majority of kidney diseases that are associ-ated with monoclonal gammopathy are secondary to deposi-tion of light chains (� or �) and not heavy chains or intact Igs(73). These include myeloma kidney (cast nephropathy), Iglight chain (AL) amyloidosis, and light chain deposition disease(74). The spectrum of renal lesions that are associated withmonoclonal gammopathy is extensive and depends on thephysiochemical properties of the Ig produced (75). It should bepointed out that whereas light chain deposition with an MPGNpattern of injury is a widely known entity, MPGN secondary tointact monoclonal Igs is less frequently recognized.

We recently analyzed renal biopsies of patients who receiveda diagnosis of MPGN at the Mayo Clinic during a 6-year periodfrom 2001 through 2006 (76). Among the 65 patients withhepatitis-negative MPGN, we identified 28 (43.1%) patientswho were positive for monoclonal/biclonal Igs. Immunofluo-rescence microscopy showed granular immune deposits in themesangium and/or along the capillary walls, consisting of IgMFigure 15. Answers from the membership, question 7.

Table 4. Conditions associated with an MPGN patternof injury

Chronic infectionsviral: Hepatitis C, hepatitis B (rarely)bacterial: Endocarditis, infected ventriculo-atrial

shunt, visceral abscesses, leprosy, meningococcalmeningitis

protozoa/other infections: Malaria, schistosomiasis,mycoplasma, leishmaniasis

Autoimmune diseasesSLESjögren syndromerheumatoid arthritisC2 deficiency and SLE-like disease

Inherited complement deficiencies (e.g., CFH, CFI, C3deficiency)

Monoclonal gammopathiesOther neoplasias (e.g., lung cancer, lymphoma)Chronic and healed TMAs

healing phase of HUS/TTPantiphospholipid (anticardiolipin) antibodies

syndromeradiation nephritisnephropathy associated with bone marrow

transplantationdrug-associated thrombotic angiopathiessickle cell anemia and polycythemiadysfibrinogenemia and other prothrombotic statesTG

POEMS syndromeIdiopathic forms of MPGN

MPGN type IMPGN type II or dense-deposit diseaseMPGN type III/IV (Strife and Burkholder variants)

TTP, thrombotic thrombocytopenic purpura.


� (n � 11), IgG � (n � 4), IgG only (n � 2), IgG � (n � 1), IgM� (n � 1), and IgG/IgM � (n � 1). These results correlated withimmunofixation results (in two cases, IgG was noted in themesangium and along capillary walls, but light chain restrictionwas not documented). In most biopsies, the deposits were moreprominent along the capillary walls than in the mesangium,whereas in a few others the reverse was true. Three biopsies didnot contain glomeruli or contained only globally sclerotic glo-meruli, and in five biopsies, significant immune deposits werenot noted; however, three of the five negative cases showed C3along the capillary walls. On electron microscopy examination,there was thickening of the capillary walls with subendothelialdeposits in all cases. Cellular interposition and new basementmembrane formation with double contours were also seen. Thedeposits were granular, and substructures were typically ab-sent. In four biopsies, scattered subepithelial deposits could beidentified. The mesangium also contained electron-dense de-posits in 21 cases. Podocytes showed segmental effacement ofthe foot processes, and many of the capillary loops showedleukocyte infiltration. Tubuloreticular structures were absent inthe endothelial cells.

Sixteen of the 28 patients had a normal bone marrow biopsyand were classified as having a monoclonal gammopathy ofunknown significance (MGUS). The diagnosis of MGUS re-quires a serum monoclonal paraprotein band of �30 g/L; abone marrow biopsy that shows �10% plasma cells; and ab-sence of end organ damage such as lytic bone lesions, anemia,hypercalcemia, and kidney failure. It is the most commonplasma cell disorder recognized and is a potential precursor formultiple myeloma (77,78). Thus, the important finding of thisstudy is the association of MPGN with MGUS. This study alsoshows that in addition to MGUS, a membranoproliferativepattern of injury can be seen in the setting of conditions that areassociated with a monoclonal gammopathy, such as B celllymphomas, chronic lymphocytic leukemia, and multiple my-eloma. In one case, serum protein electrophoresis studies werenegative even though the renal biopsy suggested an MPGNsecondary to monoclonal gammopathy. A few months after thebiopsy, serum immunofixation results turned positive for amonoclonal gammopathy. Thus, MPGN may often be the firstsign of the underlying lymphoplasmacytic disorder. Althougha direct relationship between the presence of a monoclonalprotein and the development of an MPGN remains to beproved, these observations point in that direction.

Recently, Nasr et al. (79) described an entity of proliferativeglomerulonephritis associated with IgG deposition. That study,however, differs from our observations in that the depositswere composed exclusively of monoclonal IgG and thus maybelong to a subgroup of patients with monoclonal IgG. Bonemarrow biopsy was performed in 22 of 37 patients, only one ofwhom showed multiple myeloma. Because a monoclonal gam-mopathy was identified in only 30% of the cases, the authorsdid not associate the lesions with MGUS, lymphoproliferativedisease, or multiple myeloma.

In this case, a repeat renal biopsy was performed at presen-tation to our institution and showed glomeruli with mesangialexpansion, increased cellularity, and endocapillary prolifera-

tion and capillary walls with double contours. In three glomer-uli, extracapillary proliferation resulted in the formation ofcellular crescents with fibrinoid necrosis. Immunofluorescenthistology showed granular staining for IgG (2�), IgM (1 to 2�),C1q (1 to 2�), C3 (3�), and � light chain (3�) along thecapillary walls. � light chain and IgA were negative. Electronmicroscopy showed no tubuloreticular structures and no mes-angial deposits. These findings led us to make the diagnosis ofan MPGN secondary to a monoclonal gammopathy.

A pauci-immune crescentic glomerulonephritis (A) is themost common cause of rapidly progressive glomerulonephritisin patients who are older than 60 years (80). In these cases,ANCA is present in �90% of patients at initial presentation(81). Although nephrotic-range proteinuria can occur in thesetting of ANCA-associated vasculitis, the absence of ANCAtogether with massive proteinuria makes this diagnosis un-likely. Cryoglobulinemic glomerulonephritis (B) can present aspart of a renal-dermatologic small-vessel vasculitis syndrome.Cryoglobulinemic glomerulonephritis is typically associatedwith positive hepatitis C serology, positive cryoglobulins, andlow C4, all of which were absent in this case. C1q nephropathy(D) is a glomerulonephritis that is characterized by predomi-nant mesangial C1q deposition but with other histologic fea-tures resembling lupus nephritis (e.g., capillary wall thickeningrecognizable as “wire loops,” a “full house” on immunofluo-rescence microscopy, and electron-dense deposits in mesangialand subendothelial locations) (82). Clinical features of SLE areabsent at presentation, although some patients may developpositive lupus serology and overt clinical lupus on follow-up.In this case, renal biopsy showed no features suggestive oflupus nephritis or C1q predominance, making this diagnosisunlikely. In diffuse proliferative lupus nephritis (E) a positiveANA is present in �95% of patients; however, ANA lacksspecificity and can occur, usually in low titers, as a result ofcross-reactivity with other autoantibodies. Hematuria and pro-teinuria in the setting of lupus nephritis are usually associatedwith low complement levels, and anti-dsDNA antibodies arestrongly positive. This patient had normal complement levelsand negative anti-dsDNA, making the diagnosis of lupus ne-phritis less likely.

There is no standard treatment for patients with MPGNassociated with a monoclonal gammopathy. Conservative aswell as immunosuppressive therapy with the use of corticoste-roids (alone or in combination with an alkylating agent), tha-lidomide, bortezomib (Velcade), mycophenolate mofetil, cyclo-sporine, and rituximab have been used in a small number ofpatients with variable outcomes (79). Prospective, controlledstudies of larger cohorts of patients with MPGN and monoclo-nal gammopathy are needed to ascertain optimal therapy. Atpresent, treatment decisions will have to be made purely on thebasis of clinical experience. In this case, the patient was treatedwith two pulses of methylprednisolone (1 g each) followed byprednisone 60 mg/d, tapered down to 40 mg/d at 4 weeks,with subsequent tapering by 10 mg every 2 weeks until discon-tinuation. The patient also received concomitant treatment withcyclophosphamide (1 mg/kg per day, orally) for 3 months. Oralsulfamethoxazole-trimethoprim was used for Pneumocystis ji-


roveci pneumonia prophylaxis. When last seen in October 2009,serum creatinine level was 1.8 mg/dl, proteinuria had comedown to 4.3 g/24 h, and urinary sediment was inactive.

In summary, many patients with an MPGN pattern of injuryon renal biopsy have an underlying monoclonal gammopathy,and renal biopsies should be analyzed with anti–light chainantibodies to detect a possible underlying monoclonal gam-mopathy. Similarly, all patients with MPGN should undergo afull workup for gammopathies, which should include serumand urine immunofixation studies. When positive, a bone mar-row biopsy should also be performed. As it stands, “idiopathic”MPGN seems to be a vanishing disease and a possible under-lying cause is likely to be found in the majority of cases ofMPGN.

Case 8: Fernando C. FervenzaA 60-year-old man with a history of hypertension and type 2

diabetes for 10 years was evaluated for sudden onset of massiveproteinuria (45 g/d). Renal biopsy showed 24 glomeruli, six ofwhich were totally sclerotic. All of the glomeruli showed mes-angial expansion with formation of homogeneous acellular pe-riodic acid-Schiff– and silver-negative nodules. Congo redstains were positive and showed reddish brown material thatshowed apple green birefringence under polarized light. Im-munofluorescence study showed glomerular staining for IgG(1�), IgA (trace to 1�), IgM (2 to 3�), C3 (2�), C1q (2�), fibrin(2 to 3�), � (trace to 1�), and � (1�). Electron microscopyshowed mesangial expansion with amyloid fibrils. Staining forserum amyloid protein (SAP) was positive, but staining forserum amyloid A (SAA) protein was negative. Serum immuno-fixation was negative, whereas urine immunoelectrophoresisshowed polyclonal � and � light chains. Bone marrow biopsywas negative for monoclonal plasma cells.

Question 8Which ONE of the following is the MOST appropriate next step(Figure 16)?

A. Proceed with high-dosage melphalan followed by autolo-gous stem cell transplantation (ASCT).

B. Begin treatment with vincristine, adriamycin, and dexa-methasone for three cycles, then proceed with high-dosagemelphalan and ASCT.

C. Conduct scintigraphy with labeled SAP component.D. Conduct genetic testing for hereditary amyloid variants.E. Start oral colchicine and an ACEI.

Discussion of Case 8 (Question 8)Conduct genetic testing for hereditary amyloid variants (D) isthe correct answer. The diagnosis of amyloidosis is usuallybased on positive Congo red and/or Thioflavin T stain. Routinesubtyping of amyloidosis into AL amyloidosis (light chain–associated amyloid) and AA amyloidosis (secondary amyloid)is then done by immunochemistry staining for � and � lightchains, SAP, and SAA protein. In AL amyloidosis, the amyloidstains for SAP and either � or � light chain. In case of AAamyloidosis, the amyloid stains for SAP and SAA protein but is

negative for either light chain. In this case, the renal biopsyfinding are not compatible with the diagnosis of AL amyloid orAA amyloid. If the amyloid protein cannot be typed into AL orAA subtypes, then it should raise suspicion for a hereditaryamyloidosis and the diagnosis of a hereditary form should bepursued by serum isoelectric focusing, DNA sequencing,and/or mass spectrometry of the amyloid protein (83) (Table 5).

Hereditary systemic amyloidoses are usually derived fromgenetic variants of transthyretin (familial amyloid polyneurop-athy), apolipoprotein AI, apolipoprotein AII, lysozyme, cysta-tin C, gelsolin, TNF receptor, or fibrinogen A �-chain (AFib)(84). These diseases all are inherited in an autosomal dominantmanner with variable penetrance. Variations in the gene muta-tions result in clinical amyloidosis syndromes that differ withrespect to clinical presentation, age of onset, organ distribution,rate of progression, and prognosis. Of these conditions, themost common is caused by mutations in the transthyretin gene.Patients usually have a family history of progressive peripheraland autonomic neuropathy secondary to amyloid, althoughinvolvement of the heart or kidneys is variable. Conversely, thekidney is usually involved in amyloidosis caused by mutationsin the genes that encode lysozyme, apolipoproteins AI and AII,or AFib (84); however, these autosomal dominant conditionsare generally not considered in the differential diagnosis forpatients without a relevant family history. Lachmann et al. (85)reported on 350 patients who had systemic amyloidosis and forwhom a diagnosis of AL amyloidosis had been made on thebasis of clinical and laboratory findings and by the absence ofa family history. Testing these patients for amyloidogenic mu-tations showed that mutations were present in 34 (9.7%) of the350 patients, most often in the genes that encode AFib (18patients) and transthyretin (13 patients). In all 34 of thesepatients, the diagnosis of hereditary amyloidosis was con-firmed by additional investigations. Of note, a low-grademonoclonal gammopathy (�0.2 g/dl) was detected in eight(24%) of the 34 patients, but in none of these patients were freelight chains detected in the urine. Because MGUS can be foundin 3.2% of individuals who are 50 years of age and increases to5.3% among individuals who are aged �70 years (77), the



detection of a monoclonal protein in a patient with the diagno-sis of amyloidosis may result in misleading the diagnosis as ALamyloidosis. In the report by Lachmann et al. (85), four of the 18patients with AFib mutation had a monoclonal gammopathy;the presence of these monoclonal gammopathies reinforced theinitial misdiagnosis of AL amyloidosis, and three of the fourpatients received cytotoxic chemotherapy. Thus, it is importantthat the diagnosis of hereditary amyloidosis be considered for allpatients who receive a diagnosis of amyloidosis but for whombiopsy stains are negative for the reactive systemic amyloid AAtype and confirmation of the AL type cannot be obtained.

In this case, subsequent DNA sequencing showed a mutationin valine 526 position of the AFib, leading to a diagnosis ofhereditary AFib amyloidosis. Hereditary AFib amyloidosis hasbeen the subject of a number of publications (86–90). Patientswith AFib amyloidosis typically present in middle age withproteinuria, hypertension, and progressive renal failure thatreaches ESRD within 4 to 8 years (87). A family history of renaldisease is frequently absent. Renal biopsy often shows massiveaccumulation of amyloid in the glomeruli but little or no inter-stitial or vascular amyloid. The most common amyloidogenicmutation in the fibrinogen gene is the single-base substitutionof glutamic acid to valine in the codon at position 526 (as wasnoted in our patient). Other mutations at codons 552, 540, 538,and 525 have also been described (87). In patients with AFibamyloidosis, clinical manifestations are typically restricted tothe kidney, with significant extrarenal disease being very rare.In the report by Gillmore et al. (87), median time from presen-tation to ESRD was 4.6 years, and the estimated median patientsurvival was 15.2 years. Among 44 patients who reached ESRD,median survival was 9.3 years. Kidney transplantation alonehas been performed in a number of patients with AFib amy-loidosis, and in the series by Gillmore et al., 12 kidney trans-plants survived for a median of 6.0 years (range 0.0 to 12.2years), whereas seven grafts failed after a median follow-upfrom transplantation of 5.8 years; however, unless the supply ofthe abnormal amyloidogenic protein could be reduced, AFibamyloidosis will recur after a kidney transplant and may resultin allograft loss (76,87). Combined kidney liver transplantation

has been attempted as a way to prevent recurrence from he-reditary AFib amyloidosis with some success (87,91). Livertransplantation removes the source of the circulating fibrinogenvariant. Combined kidney-liver transplantation has also beendone in a case with no evidence of recurrence of AFib amyloid-osis (92); however, it has been argued that because recurrentAFib amyloidosis develops slowly, liver transplantation shouldbe considered only for patients or families in whom fast recur-rence has resulted in accelerated loss in a first kidney transplantor when the involved mutation is known to result in fastrecurrence in the graft (91).

Light chain amyloidosis (AL), formerly known as primaryamyloidosis, is the most common form of amyloidosis and canrespond to therapy that is directed at the underlying plasmacell dyscrasia (93–95). Thus, high-dosage melphalan followedby ASCT (A) would be appropriate if the patient had ALamyloidosis. In this case, the absence of a monoclonal proteinon serum and urine immunofixation studies together with abone marrow biopsy showing no monoclonal plasma cells rulesout the diagnosis of AL amyloidosis. The use of vincristine,adriamycin, and dexamethasone for induction before ASCT (B)had been tested in 28 patients with AL amyloidosis (96). In thisstudy, four patients died before ASCT (two from progression,two from treatment). No additional benefits were found incomparison with ASCT alone; therefore, induction chemother-apy before ASCT is not recommended.

Scintigraphy with labeled SAP component (C) has been usedto quantify imaging of amyloid deposits in vivo but is nonspe-cific for any particular type of amyloidosis (97). Similarly, ther-apy with colchicine and an ACEI would be appropriate forpatients with a diagnosis of familiar Mediterranean fever(FMF). FMF usually occurs during childhood, with 60% ofpatients showing first symptoms before the age of 10 years (98).FMF is clinically characterized by bouts of fever and serositis(peritonitis, synovitis, or pleuritis) that last 1 to 3 days (99). Skininvolvement is also common, generally as an erysipela-like rashthat occurs most frequently on the shins and dorsum of thefoot. AA amyloidosis can develop in a significant percentage of

Table 5. Causes of systemic amyloidosis

Amyloid Protein Precursor Syndrome or Involved Tissue

ALa Ig light chain Primary; myeloma-associatedAHa Ig heavy chain Primary; myeloma-associatedA�2Ma �2-microglobulin Hemodialysis-associated; jointsATTR Transthyretin Familial; senile systemicAA (Apo) serum AA Secondary, reactiveAApoAI Apolipoprotein AI FamilialAApoAIV Apolipoprotein AIV Sporadic, associated with agingAGel Gelsolin Familial (Finnish)ALys Lysozyme FamilialAFib Fibrinogen �-chain FamilialACys Cystatin C FamilialABri ABriPP Familial dementia, British

aCan be localized/organ restricted.


patients with FMF. None of these findings was present in thiscase, and stain for AA amyloid was negative.

DisclosuresNone.

References1. Friedman O, Jassal S, Bargman J: Acinetobacter peritoneal

dialysis peritonitis: Description and relation to the SPICEfamily of organisms. Perit Dial Int 28: 195–197, 2008

2. Rodriguez-Bano J, Pascual A: Clinical significance of ex-tended-spectrum beta-lactamases. Expert Rev Anti InfectTher 6: 671–683, 2008

3. Turner P: Extended-spectrum beta-lactamases. Clin InfectDis 41[Suppl 4]: S273–S275, 2005

4. Harada S, Ishii Y, Yamaguchi K: Extended-spectrum beta-lactamases: Implications for the clinical laboratory andtherapy. Korean J Lab Med 28: 401–412, 2008

5. Matuszkiewicz-Rowinska J: Update on fungal peritonitis andits treatment. Perit Dial Int 29[Suppl 2]: S161–S165, 2009

6. Chou C, Kao M, Kuo H, Liu J, Liu Y, Huang C: Gram-negative and polymicrobial peritonitis are associated withsubsequent fungal peritonitis in CAPD patients. Perit DialInt 26: 607–608, 2006

7. Goldie S, Kiernan-Tridle L, Torres C, Gorban-Brennan N,Dunne D, Kliger A, Finkelstein F: Fungal peritonitis in alarge chronic peritoneal dialysis population: A report of 55episodes. Am J Kidney Dis 28: 86–91, 1996

8. Zaruba K, Peters J, Jungbluth H: Successful prophylaxis forfungal peritonitis in patients on continuous ambulatoryperitoneal dialysis: Six years’ experience. Am J Kidney Dis17: 43–46, 1991

9. Wong P, Lo K, Tong G, Chan S, Lo M, Mak S, Wong A:Prevention of fungal peritonitis with nystatin in patientsreceiving CAPD. Perit Dial Int 27: 531–536, 2007

10. Piraino B, Bernardini J, Fried L, Johnston J: Pain due toperitonitis. Perit Dial Int 19: 583–584, 1999

11. Divino Filho JC: Allergic reactions to icodextrin in patientswith renal failure. Lancet 355: 1364–1365, 2000

12. Gokal R: Icodextrin-associated sterile peritonitis. Perit DialInt 22: 445–448, 2002

13. Elwell R, Manley H, Frye R, Bailie G: Pharmacokinetics ofintraperitoneal cefazolin and ceftazidime co-administeredto CAPD patients. Int J Artif Organs 28: 808–816, 2005

14. US Renal Data System: USRDS 2008 Annual Data Report,Bethesda, National Institute of Diabetes and Digestive andKidney Diseases, 2008

15. Marr K, Sexton D, Conlon P, Corey G, Schwab S, KirklandK: Catheter-related bacteremia and outcome of attemptedcatheter salvage in patients undergoing hemodialysis. AnnIntern Med 127: 275–280, 1999

16. Saad T: Bacteremia associated with tunnelled, cuffed he-modialysis catheters. Am J Kidney Dis 34: 1114–1124, 1999

17. Kovalik E, Raymond J, Albers F, Berkoben M, Butterly D,Montella A, Conlon P: A clustering of epidural abscesses inchronic hemodialysis patients: Risks of salvaging accesscatheters in cases of infection. J Am Soc Nephrol 7: 2264–2267, 1996

18. Philipneri M, Al-Aly Z, Amin K, Gellens M, Bastani B:Routine replacement of tunneled, cuffed, hemodialysis

catheters eliminates paraspinal/vertebral infections in pa-tients with catheter-associated bacteremia. Am J Nephrol 23:202–207, 2003

19. Ashby D, Power A, Singh S, Choi P, Taube D, Duncan N,Cairns T: Bacteremia associated with tunnelled hemodial-ysis catheters: Outcome after attempted salvage. Clin J AmSoc Nephrol 4: 1601–1605, 2009

20. Carlisle E, Blake P, McCarthy F, Vas S, Uldall R: Septicemiain long-term jugular hemodialysis catheters: Eradicatinginfection by changing the catheter over a guidewire. Int JArtif Organs 14: 150–153, 1991

21. Shaffer D: Catheter-related sepsis complicating long-term,tunnelled central venous dialysis catheters: Managementby guidewire exchange. Am J Kidney Dis 25: 593–596, 1995

22. Robinson D, Suhocki P, Schwab S: Treatment of infectedtunnelled venous access hemodialysis catheters withguidewire exchange. Kidney Int 53: 1792–1794, 1998

23. Tanriover B, Carlton D, Saddekni S, Hamrick K, Oser R,Westfall A, Allon M: Bacteremia associated with tunnelleddialysis catheters: Comparison of two treatment strategies.Kidney Int 57: 2151–2155, 2000

24. Mokrzycki M, Zhang M, Cohen H, Golestaneh L, Laut J,Rosenberg S: Tunnelled haemodialysis catheter bacterae-mia: Risk factors for bacteraemia recurrence, infectiouscomplications and mortality. Nephrol Dial Transplant 21:1024–1031, 2006

25. Vardhan A, Davies J, Daryanani I, Crowe A, McClelland P:Treatment of haemodialysis catheter-related infections.Nephrol Dial Transplant 17: 1149–1150, 2002

26. Poole C, Carlton D, Bimbo L, Allon M: Treatment of cath-eter-related bacteraemia with an antibiotic lock protocol:effect of bacterial pathogen. Nephrol Dial Transplant 19:1237–1244, 2004

27. Maya I, Carlton D, Estrada E, Allon M: Treatment of dial-ysis catheter-related Staphylococcus aureus bacteremia withan antibiotic lock: A quality improvement report. Am JKidney Dis 50: 289–295, 2007

28. Duncan A: Screening for surreptitious laxative abuse. AnnClin Biochem 37: 1–8, 2000

29. Perez GO, Oster JR, Rogers A: Acid-base disturbances ingastrointestinal disease. Dig Dis Sci 32: 1033–1043, 1987

30. Oster JR, Materson BJ, Rogers AI: Laxative abuse syn-drome. Am J Gastroenterol 4: 451–458, 1980

31. Dick WH, Lingeman JE, Preminger GM, Smith LH, WilsonDM, Shirrell WL: Laxative abuse as a cause for ammoniumurate renal calculi. J Urol 143: 244–247, 1990

32. Robertson WG: Renal stones in the tropics. Semin Nephrol23: 77–87, 2003

33. Shelton JH, Santa Ana CA, Thompson DR, Emmett M, Fordt-ran JS: Factitious diarrhea induced by stimulant laxatives:Accuracy of diagnosis by a clinical reference laboratory usingthin layer chromatography. Clin Chem 53: 85–90, 2007

34. Landau D, Kher KK: Gentamicin-induced Bartter-like syn-drome. Pediatr Nephrol 11: 737–740, 1997

35. Shiah CJ, Tsai DM, Liao ST, Siauw CP, Lee LS: Acutemuscular paralysis in an adult with subclinical Bartter’ssyndrome associated with gentamicin administration. Am JKidney Dis 24: 932–935, 1994

36. Chou CL, Yeong-Hwang C, Chau T, Lin S: Acquired Bar-tter-like syndrome associated with gentamicin administra-tion. Am J Med Sci 329: 144–149, 2005

37. Sassen MC, Kim SW, Kwon TH, Knepper MA, Miller RT,


Frokiaer J, Nielsen S: Dysregulation of renal sodium trans-porters in gentamicin-treated rats. Kidney Int 70: 1026–1037, 2006

38. Zietse R, Zoutendijk R, Hoorn EJ: Fluid, electrolyte andacid-base disorders associated with antibiotic therapy. NatRev Nephrol 5: 193–202, 2009

39. Babu E, Takeda M, Nariwaka S, Kobayashi Y, YamamotoT, Cha SH, Sekine T, Sakthisekaran D, Endou H: Humanorganic anion transporters mediate the transport of tetra-cycline. Jpn J Pharmacol 88: 69–76, 2002

40. Saul RF, Selhorst JB: Downbeat nystagmus with magne-sium depletion. Arch Neurol 38: 650–652, 1981

41. Du Pasquier R, Vingerhoets F, Safran AB, Landis T: Peri-odic downbeat nystagmus. Neurology 51: 1478–1480, 1998

42. Allford SL, Hunt BJ, Rose P, Machin SJ: Haemostasis andThrombosis Task Force, British Committee for Standardsin Haematology: Guidelines on the diagnosis and manage-ment of the thrombotic microangiopathies haemolyticanaemias. Br J Haematol 120: 556–573, 2003

43. Ponticelli C, Banfi G: Thrombotic microangiopathy afterkidney transplantation. Transpl Int 19: 789–794, 2006

44. Kavanagh D, Richards A, Fremeaux-Bacchi V, Noris M,Goodship T, Remuzzi G, Atkinson JP: Screening for com-plement system abnormalities in patients with atypicalhemolytic uremic syndrome. Clin J Am Soc Nephrol 2: 591–596, 2007

45. Loirat C, Noris M, Fremaux-Bacchi V: Complement andthe atypical hemolytic uremic sydrome in children. PediatrNephrol 23: 1957–1972, 2008

46. Kavanagh D, Goodship T: Membrane cofactor protein andfactor I: Mutations and transplantation. Semin Thromb Hae-most 32: 155–159, 2006

47. Moore I, Strain L, Pappworth I, Kavanagh D, Barlow PN,Herbert AP, Schmidt CQ, Staniforth SJ, Holmes LV, WardR, Morgan L, Goodship TH, Marchbank KJ: Association offactor H autoantibodies with deletions of CFHR1, CFHR3,CFHR4 and with mutations in CFH, CFI, CD46, and C3 inpatients with atypical hemolytic uremic syndrome. Blood115: 379–387, 2010

48. Le Quintrec M, Lionet A, Kamar N, Karras A, Barbier S,Buchler M, Fakhouri F, Provost F, Fridman WH, Thervet E,Legendre C, Zuber J, Fremeaux-Bacchi V: Complementmutation-associated de novo thrombotic microangiopathyfollowing kidney transplantation. Am J Transplant 8: 1694–1701, 2008

49. Ruggenenti P: Post-transplant hemolytic-uremic syndrome. Kid-ney Int 62: 1093–1104, 2002

50. Loirat C, Fremeaux-Bacchi V: Hemolytic uremic syndromerecurrence after renal transplantation. Pediatr Transplant 12:619–629, 2008

51. Tsai H-M, Lian EC-Y: Antibodies to von Willebrand factor-cleaving protease in acute thrombotic thrombocytopenicpurpura. N Engl J Med 339: 1585–1594, 1998

52. Furlan M, Robles R, Galbusera M, Remuzzi G, Kyrle PA,Brenner B, Krause M, Scharrer I, Aumann V, Mittler U, So-lenthaler M, Lammle B: von Willebrand factor-cleaving pro-tease in thrombotic thrombocytopenic purpura and the he-molytic-uremic syndrome. N Engl J Med 339: 1578–1584, 1998

53. Saland J, Ruggenenti P, Remuzzi G: Liver-kidney trans-plantation to cure atypical hemolytic uremic syndrome.J Am Soc Nephrol 20: 940–949, 2009

54. Ducloux D, Rebibou JM, Semhoun-Ducloux S, Jamali M,

Fournier V, Bresson-Vautrin C, Chalopin JM: Recurrence ofhemolytic uremic syndrome in renal transplant recipients.Transplantation 65: 1405–1407, 1998

55. Chan MR, Thomas CP, Torrealba JR, Djamali A, FernandezLA, Nishimura C, Smith RJ, Samaniego MD: Recurrentatypical hemolytic uremic syndrome associated with factorI mutation in a living related renal transplant recipient.Am J Kidney Dis 53: 321–326, 2009

56. Racusen LC, Colvin RB, Solez K, Mihatsch MJ, HalloranPF, Campbell PM, Cecka MJ, Cosyns JP, Demetris AJ,Fishbein MC, Fogo A, Furness P, Gibson IW, Glotz D,Hayry P, Hunsickern L, Kashgarian M, Kerman R, MagilAJ, Montgomery R, Morozumi K, Nickeleit V, RandhawaP, Regele H, Seron D, Seshan S, Sund S, Trpkov K: Anti-body-mediated rejection criteria: An addition to theBanff’97 classification of renal allograft rejection. Am JTransplant 3: 708–714, 2003

57. Ulinski T, Charpentier A, Colombat M, Desconclois C,Mougenot B, Fremaux-Bacchi V, Suberbielle C, DeschenesG, Bensman A, Veyradier A: From humoral rejection togeneralized thrombotic microangiopathy: Role of acquiredADAMST-13 deficiency in a renal allograft recipient [erra-tum appears in Am J Transplant 7: 730, 2007]. Am J Trans-plant 6: 3030–3036, 2006

58. Pham PT, Danovitch GM, Wilkinson AH, Gritsch HA,Pham PC, Eric TM, Kendrick E, Charles LR, Tsai HM:Inhibitors of ADAMST13: A potential factor in the cause ofthrombotic microangiopathy in a renal allograft recipient.Transplantation 74: 1077–1080, 2002

59. Pham PT, Peng A, Wilkinson AH, Gritsch HA, Lassman C,Pham PC, Danovitch GM: Cyclosporine and tacrolimus-associated thrombotic microangiopathy. Am J Kidney Dis36: 844–850, 2000

60. Gebel HM, Bray RA, Nickerson P: Pre-transplant assess-ment of donor reactive, HLA-specific antibodies in renaltransplantation: contraindication vs risk. Am J Transplant 3:1488–1500, 2003

61. Mihaylova A, Baltadjieva D, Boneva P, Ivanova M, Penkova K,Marinova D, Mihailova S, Paskalev E, Simeonov P, Naumova E:Clinical relevance of anti-HLA antibodies detected byflow-cytometry bead-based assays: Single center experi-ence. Hum Immunol 67: 787–794, 2006

62. Schnitzler MA, Hollenbeak CS, Woodward RS, Lowell JA,Singer GG, Tesi RJ, Howard TK, Mohanakumar T, BrennanDC: The economic implications of HLA matching in cadav-eric renal transplantation. N Engl J Med 341: 1440–1446, 1999

63. Irish W, Sherrill B, Brennan DC, Lowell J, Schnitzler M:Three-year post-transplant graft survival in renal-trans-plant patients with graft function at 6 months receivingtacrolimus or cyclosporine microemulsion within a triple-drug regimen. Transplantation 76: 1686–1690, 2003

64. Irish WD, McCollum DA, Tesi RJ, Owen AB, Brennan DC,Bailly JE, Schnitzler MA: Nomogram for predicting the like-lihood of delayed graft function in adult cadaveric renaltransplant recipients. J Am Soc Nephrol 14: 2967–2974, 2003

65. Zarifian A, Meleg-Smith S, O’Donovan R, Tesi RJ, BatumanV: Cyclosporine-associated thrombotic microangiopathy inrenal allografts. Kidney Int 55: 2457–2466, 1999

66. Taylor VC, Sims M, Brett S, Field M: Antibody selectionagainst CD52 produces paroxysmal nocturnal haemoglo-binuria phenotype in human lymphocytes by a novelmechanism. Biochem J 322: 919–925, 1997


67. Bonatti H, Brandacher G, Boesmueller C, Cont M, Hengster P,Rosenkranz AR, Krugmann J, Margreiter R: Hemolytic ure-mic syndrome following Campath-1H induction. Transpl Int20: 386–389, 2007

68. Solez K, Colvin RB, Racusen LC, Sis B, Halloran PF, BirkPE, Campbell PM, Cascalho M, Collins AB, Demetris AJ,Drachenberg CB, Gibson IW, Grimm PC, Haas M, Lerut E,Liapis H, Mannon RB, Marcus PB, Mengel M, Mihatsch MJ,Nankivell BJ, Nickeleit V, Papadimitriou JC, Platt JL,Randhawa P, Roberts I, Salinas-Madriga L, Salomon DR,Seron D, Sheaff M, Weening JJ: Banff ’05 meeting report:Differential diagnosis of chronic allograft injury and elim-ination of chronic allograft nephropathy (CAN). Am JTransplant 7: 518–526, 2007

69. Sis B, Campbell PM, Mueller T, Hunter C, Cockfield SM,Cruz J, Meng C, Wishart D, Solez K, Halloran PF: Trans-plant glomerulopathy, late-antibody-mediated rejectionand the ABCD tetrad in kidney allograft biopsies for cause.Am J Transplant 7: 1743–1752, 2007

70. Gloor JM, Sethi S, Stegall MD, Park WD, Moore SB,DeGoey S, Griffin MD, Larson TS, Cosio FG: Transplantglomerulopathy: Subclinical incidence and associationwith alloantibody. Am J Transplant 7: 2124–2132, 2007

71. Ivanyi B: A primer on recurrent and de novo glomerulo-nephritis in renal allografts. Nat Clin Pract Nephrol 4: 446–457, 2008

72. Wojciechowski D, Onozato ML, Gonin J: Rapid onset ofdiabetic nephropathy in three renal allografts despite nor-moglycemia. Clin Nephrol 71: 719–724, 2009

73. Sanders PW, Herrera GA: Monoclonal immunoglobulinlight chain-related renal diseases. Semin Nephrol 13: 324–341, 1993

74. Leung N, Rajkumar SV: Renal manifestations of plasmacell disorders. Am J Kidney Dis 50: 155–165, 2007

75. Audard V, Georges B, Vanhille P, Toly C, Deroure B,Fakhouri F, Cuvelier R, Belenfant X, Surin B, AucouturierP, Mougenot B, Ronco P: Renal lesions associated withIgM-secreting monoclonal proliferations: Revisiting thedisease spectrum. Clin J Am Soc Nephrol 3: 1339–1349, 2008

76. Sethi S, Fervenza FC, Miller D, Norby S, Leung N: Recur-rence of amyloidosis in a kidney transplant. Am J KidneyDis February 21, 2010 [epub ahead of print]

77. Kyle RA, Therneau TM, Rajkumar SV, Larson DR, PlevakMF, Offord JR, Dispenzieri A, Katzmann JA, Melton LJ 3rd:Prevalence of monoclonal gammopathy of undeterminedsignificance. N Engl J Med 354: 1362–1369, 2006

78. Kyle RA, Therneau TM, Rajkumar SV, Offord JR, LarsonDR, Plevak MF, Melton LJ 3rd: A long-term study of prog-nosis in monoclonal gammopathy of undetermined signif-icance. N Engl J Med 346: 564–569, 2002

79. Nasr SH, Satoskar A, Markowitz GS, Valeri AM, Appel GB,Stokes MB, Nadasdy T, D’Agati VD: Proliferative glomer-ulonephritis with monoclonal IgG deposits. J Am Soc Neph-rol 20: 2055–2064, 2009

80. Jennette JC: Rapidly progressive crescentic glomerulone-phritis. Kidney Int 63: 1164–1177, 2003

81. Jennette JC, Falk RJ: New insight into the pathogenesis ofvasculitis associated with antineutrophil cytoplasmic auto-antibodies. Curr Opin Rheumatol 20: 55–60, 2008

82. Sharman A, Furness P, Feehally J: Distinguishing C1q ne-phropathy from lupus nephritis. Nephrol Dial Transplant 19:1420–1426, 2004

83. El-Zoghby Z, Lager D, Gregoire J, Lewin M, Sethi S: Intra-tubular amyloidosis. Kidney Int 72: 1282–1288, 2007

84. Picken MM: New insights into systemic amyloidosis: Theimportance of diagnosis of specific type. Curr Opin NephrolHypertens 16: 196–203, 2007

85. Lachmann HJ, Booth DR, Booth SE, Bybee A, GilbertsonJA, Gillmore JD, Pepys MB, Hawkins PN: Misdiagnosis ofhereditary amyloidosis as AL (primary) amyloidosis.N Engl J Med 346: 1786–1791, 2002

86. Benson MD, Liepnieks J, Uemichi T, Wheeler G, Correa R:Hereditary renal amyloidosis associated with a mutantfibrinogen alpha-chain. Nat Genet 3: 252–255, 1993

87. Gillmore JD, Lachmann HJ, Rowczenio D, Gilbertson JA,Zeng CH, Liu ZH, Li LS, Wechalekar A, Hawkins PN:Diagnosis, pathogenesis, treatment, and prognosis of he-reditary fibrinogen A alpha-chain amyloidosis. J Am SocNephrol 20: 444–451, 2009

88. Hamidi Asl L, Liepnieks JJ, Uemichi T, Rebibou JM,Justrabo E, Droz D, Mousson C, Chalopin JM, Benson MD,Delpech M, Grateau G: Renal amyloidosis with a frameshift mutation in fibrinogen alpha-chain gene producing anovel amyloid protein. Blood 90: 4799–4805, 1997

89. Lane SW, Goodman HJ, Francis L, Bofinger A, Mollee PN:Hereditary fibrinogen A alpha-chain amyloidosis. Pathol-ogy 38: 380–382, 2006

90. Uemichi T, Liepnieks JJ, Benson MD: Hereditary renalamyloidosis with a novel variant fibrinogen. J Clin Invest93: 731–736, 1994

91. Mousson C, Heyd B, Justrabo E, Rebibou JM, Tanter Y,Miguet JP, Rifle G: Successful hepatorenal transplantation inhereditary amyloidosis caused by a frame-shift mutation infibrinogen A alpha-chain gene. Am J Transplant 6: 632–635, 2006

92. Gillmore JD, Booth DR, Rela M, Heaton ND, Rahman V,Stangou AJ, Pepys MB, Hawkins PN: Curative hepatorenaltransplantation in systemic amyloidosis caused by theGlu526Val fibrinogen alpha-chain variant in an Englishfamily. QJM 93: 269–275, 2000

93. Gertz MA, Lacy MQ, Dispenzieri A, Hayman SR, Kumar S:Transplantation for amyloidosis. Curr Opin Oncol 19: 136–141, 2007

94. Leung N, Dispenzieri A, Fervenza FC, Lacy MQ, VillicanaR, Cavalcante JL, Gertz MA: Renal response after high-dose melphalan and stem cell transplantation is a favorablemarker in patients with primary systemic amyloidosis.Am J Kidney Dis 46: 270–277, 2005

95. Rajkumar SV, Gertz MA: Advances in the treatment ofamyloidosis. N Engl J Med 356: 2413–2415, 2007

96. Perz JB, Schonland SO, Hundemer M, Kristen AV, DenglerTJ, Zeier M, Linke RP, Ho AD, Goldschmidt H: High-dosemelphalan with autologous stem cell transplantation afterVAD induction chemotherapy for treatment of amyloidlight chain amyloidosis: A single centre prospective phaseII study. Br J Haematol 127: 543–551, 2004

97. Hawkins PN, Lavender JP, Pepys MB: Evaluation of sys-temic amyloidosis by scintigraphy with 123I-labeled serumamyloid P component. N Engl J Med 323: 508–513, 1990

98. Livneh A, Langevitz P, Zemer D, Padeh S, Migdal A, SoharE, Pras M: The changing face of familial Mediterraneanfever. Semin Arthritis Rheum 26: 612–627, 1996

99. Drenth JP, van der Meer JW: Hereditary periodic fever.N Engl J Med 345: 1748–1757, 2001


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