Renal Board Review – Part IApril 4, 2013

53yo man has a 3 week history of increasing weakness and anorexia. He takes no medications. On exam BP 130/70, HR 80 without orthostatic changes. No JVD, rales, or LE edema. Labs: BUN 12, Creat 0.8, Na 123, K 3.4, Cl 91, Bicarb 22, Serum Osm 270, Urine Osm 350.

What is the most likely cause of this patient’s hyponatremia?

1 2 3 4

25% 25%25%25%1. Mineralocorticoid deficiency2. Low solute diet3. Nephrotic syndrome4. SIADH

A 44-year-old man is evaluated in the hospital because of disorientation and hallucinations. He was admitted to the hospital 4 days ago for a subarachnoid hemorrhage that was repaired with surgical clipping. His medical history is otherwise unremarkable.

On physical examination, he is disoriented, confused, and hallucinating. Temperature is normal, blood pressure is 140/80 mm Hg, pulse rate is 90/min, and respiration rate is 16/min. Upon standing, his blood pressure is 120/60 mm Hg and pulse rate is 110/min. The remainder of the physical examination is normal.

Laboratory values were normal on admission, but now reveal:Na 118, K 4.1, Cl 85, Bicarb 23, Serum Osm 248, Uric acid 6.8, Spot urine Na 105, Urine Osm 633

Which of the following is the most likely cause of his hyponatremia?

1 2 3 4

25% 25%25%25%

1. Glucocorticoid insufficiency2. Cerebral salt wasting3. Hypothyroidism4. Syndrome of inappropriate antidiuretic hormone secretion

A 22-year-old woman is evaluated at an on-site medical center after collapsing while running a marathon. She is disoriented. During the evaluation, she experiences a generalized tonic-clonic seizure lasting 3 minutes. A wristband indicates that she has DM1.

On exam, BP 120/60, temp normal, HR 100, RR 28. She is confused but has no evidence of a focal neurologic deficit. Glc 120, Na 118.

Which of the following is the most appropriate next step in this patient’s management?

1 2 3 4

25% 25%25%25%1. 3% saline infusion2. 50% glucose by intravenous bolus3. Intravenous furosemide4. Normal saline infusion

HyponatremiaPlasma Osmolality

Low (<275)

Check Volume Status

Hypovolemic

Renal Losses (Una >20)

Diuretics

Mineralocorticoid insufficiency

Salt-wasting nephropathy

Cerebral Salt Wasting

Extrarenal Losses (Una <10)

Vomiting/Diarrhea

Insensible losses

Third spacing (Pancreatitis)

Euvolemic

Appropriately Low Uosm (<100)

Primary Polydypsia

Low solute diet/Beer

potomania

Inappropriately high Uosm

SIADH

Hypothyroidism

Glucocorticoid insufficiency

Hypervolemic

Nephrotic Sx

CHF

ESLD

ESRD

Normal

PseudohypoNa

Isosmotic irrigating solution

High (>295)

Mannitol

Hyperglycemia

• Goal: increase by 0.5/hr (no more than 10/24h)

• If treat too quickly, will cause CPM (seizures, AMS, paresis, resp dysfunction, etc)

Hypernatremia• Etiologies:

– Defective thirst mechanism– Inadequate access to water (elderly in nursing home)– Kidney concentrating defect (DI) – to be discussed further in Endo section– **Loss of hypotonic fluids with inadequate water replacement (GI, kidney, skin)

• Treatment– Correct slowly to avoid cerebral edema (Goal: 50% corrected in 24-36 hours)– First, make sure patient is volume replete (use isotonic saline)– Then, replace free water

• Free water deficit = TBW x [(Plasma Na/140)-1]• TBW = 0.6 x kg (male) or 0.5 x kg (female)

– Ex: 75kg female who appears euvolemic with Na of 160• TBW = 0.5(75) = 37.5• Free water deficit = 37.5 [(160/140)-1] =

5.4L

A 23-year-old man with HIV infection is evaluated in the hospital for the recent onset of hyperkalemia. He was admitted to the hospital 1 week ago for severe Pneumocystis jirovecii pneumonia; TMP-SMX and corticosteroids were begun at that time. For the past 2 months, he has been taking highly active antiretroviral therapy. Physical examination is unremarkable, and there is no evidence of hypovolemia or edema.

Labs on Admission: Na 131, K 4.8, Cl 95, Bicarb 22, BUN 20, Creat 1.3Labs Today: Na 132, K 6.2, Cl 104, Bicarb 18, BUN 21, Creat 1.4

Which of the following is the most likely cause of this patient’s hyperkalemia?

1 2 3 4 5

20% 20% 20%20%20%1. Adrenal insufficiency2. Impaired kidney potassium excretion3. Lactic acidosis4. Proximal renal tubular acidosis5. Rhabdomyolysis

Hyperkalemia• Etiologies/Mechanisms:

1. Potassium shifts (from intracellular to extracellular):– Rhabdo, hemolysis, hyperosmolar states, insulin deficiency, beta-blockers, metabolic

acidosis

2. Excessive intake (citrus, salt substitutes) - rare3. Decreased kidney excretion

– Acute/Chronic CKD; Low flow states (decreased filtration = decreased excretion)– Hyporeninemic Hypoaldosteronism (decreased Aldo = decreased Na/K exchange)

» Seen in DM nephropathy» Seen with certain meds (ACEI, Aldo antagonists, NSAIDS)

– Inhibition of distal tubule Na transport (inhibition of Na resorption = cannot secrete K)» Druge: amiloride, triamterene, TMP-SMX» Sickle Cell nephropathy; other interstitial diseases

• EKG changes• Treatment

Hypokalemia• Etiologies/Mechanisms:

1. Potassium shifts (from extracellular to intracellular)• Inhaled beta-agonists, insulin, hypothermia, excess catecholamines, metabolic

alkalosis

2. Total body depletion (associated with low urine chloride)• Vomiting, diarrhea

3. Increased Kidney Excretion• Hyperaldosteronism• Diuretics• Magnesium deficiency

• EKG changes: ST depression, T wave flattening/inversion, increased U wave

• Treatment

A 47-year-old man with a long-standing history of alcoholism is hospitalized for abdominal pain, nausea, and vomiting of 7 days’ duration. He has lost approximately 10% of his body weight over the past 4 months.

On physical examination, he appears cachectic. HR 110, other vitals wnl. There is midepigastric tenderness without rebound. Bowel sounds are present. Neurologic examination is normal.

The patient receives immediate thiamine replacement, folic acid supplementation, and a multivitamin followed by vigorous intravenous fluid replacement with 5% dextrose and normal saline with aggressive potassium replacement. Morphine is used to control pain.

Eighteen hours later, the patient’s abdominal pain has improved but he becomes restless, agitated, and extremely weak and is barely able to raise his extremities against gravity.

Which of the following is the most likely cause of this patient’s new findings?

1 2 3 4

25% 25%25%25%

1. Hypercalcemia2. Hypokalemia3. Hyponatremia4. Hypophosphatemia

HypophosphatemiaPhos: Kidney secretes 90% but reabsorbs 80% via prox tubule

• Etiologies/Mechanisms– Cellular redistribution (extracellular to intracellular)

• Refeeding syndrome after starvation• Insulin administration for severe hyperglycemia• Hungry Bone syndrome after parathyroidectomy• Respiratory alkalosis

– Decreased intestinal absorption• Antacids• Chronic diarrhea with malabsorption• Inadequate Intake: alcoholics, starvation

– Increased Urinary Excretion• Fanconi Syndrome (i.e. prox tubule dump syndrome)• Osmotic diuresis (glycosuria)• Secondary Hyperparathyroidism

Acid/Base QuestionsMethod:1. Primary disorder?2. Appropriate Compensation?3. Anion gap?4. Delta-delta?5. Osmolar gap? Delta-delta =

Anion gap

Bicarb

A 65-year-old man is evaluated for a 3-month history of progressive malaise, fatigue, and weakness. He has a 10-year history of hypertension treated with hydrochlorothiazide and atenolol. Labs are normal.

Labs: WBC 5600, Hct 25%, Plt 340k, Glc 110, Na 135, K 3.0, Cl 107, Bicarb 18, BUN 22, Creat 1.8, UA pH 5.5 trace protein and 1+ glcurine protein/creat ratio: 4.8mg/mgABG: 7.33/28/98 on RAPolarized light microscopy of urine sediment is normal

Which of the following is the most likely diagnosis?

1 2 3 4

25% 25%25%25%

1. Diabetic nephropathy2. Distal (type 1) renal tubular acidosis3. Hypertensive nephrosclerosis4. Proximal (type 2) renal tubular acidosis

A 19-year-old man is evaluated in the emergency department for altered mental status. He is accompanied by a friend, who states that the patient was asymptomatic 12 hours ago. No PMHx. He does not drink alcoholic beverages or use illicit drugs.

On physical examination, the patient is comatose. Afebrile, sats 95% on RA, BP 90/60 mm Hg, HR 110/min, and RR 28/min. Cardiopulmonary examination is normal. There are no localized findings on neurologic examination.

Labs: Glc 114, Na 142, K 3.6, Cl 108, Bicarb 14, BUN 14, Serum Osm 290, UA 1+ketonesABG: 7.42/20/94 on RA

Which of the following is the most likely cause of this patient’s acid-base disorder?

1 2 3 4

25% 25%25%25%1. Alcoholic ketoacidosis2. Ethylene glycol toxicity3. Methanol toxicity4. Salicylate toxicity

A 56-year old man with a history of alcoholism is found lying on the street. On arrival at the emergency department, he is confused.

On physical examination, temperature is 36.1 °C (97.0 °F), blood pressure is 126/80 mm Hg, and pulse rate is 70/min. Funduscopic examination shows no papilledema. Cardiac, pulmonary, and abdominal examinations are normal

Labs: Glc 86, BUN 45, Creat 2.8, Na 138, K 5.4, Cl 98, Bicarb 14, Serum Osm 316, UA with calcium oxalate crystals. ABG: 7.28/29/80 on RA

Which of the following is the most likely diagnosis?

1 2 3 4

25% 25%25%25%

1. Alcoholic ketoacidosis2. Methanol poisoning3. Ethylene glycol poisoning4. Lactic acidosis

Metabolic Acidosis

• AGMA – MUDPILES• NAGMA – HARDUP

(Hyperalimentation, Acetazolamide, RTAs, Diarrhea, Ureteroenteric fistula, Pancreatic fistula)

• RTAs– Type II (Proximal)– Type I (Distal)– Type IV

Type II RTA (proximal)• Can have isolated RTA, but more often than not, it is due to generalized dysfunction of the tubule• Proximal tubule usually responsible for reabsorbing a number of different solutes

• glc, phos, amino acids, uric acid, protein, potassium, and BICARB– All these are now excreted instead of reabsorbed (Fanconi’s Syndrome)

• Bicarb is excreted -> NAGMA– Bicarb usually around 16-18 and VERY difficult to treat with supplemental bicarb

• PO bicarb rapidly excreted in urine and can’t be reabsorbed• PO bicarb can actually worsen hypokalemia

• Causes:– Multiple Myeloma– SC disease– Heavy Metals (wilson’s Lead, Mercury)– Drugs (Ifosfamide)– Acetazolamide

• Complications:– Osteomalacia 2/2 chronic hypophos– Osteoporosis 2/2 acidosis-induced demineralization of bone

• Treatment:– Can add thiazide to decrease blood volume-> decrease GFR ->

decrease bicarb filtration – Can consider aldactone to help with potassium wasting

Type I RTA (distal)• Problem with H-ATPase – cannot excrete H+ (via NH4+) thus cannot acidify urine -> NAGMA• More severe acidosis!!

– Bicarb ~10– Severe hypokalemia– ++UAG

• Urine is electroneutral• Unmeasured anions neutralized by Na and K; unmeasured cations (typically NH4+) neutralized by Cl• UAG = (UNa+UK) – UCl

• In Type I RTA, NH4+ cannot be excreted. Decreased unmeasured cations = decreased Ucl needed to neutralize them, so will give you a net ++ urine anion gap

• Causes:– Autoimmune (Sjogren’s, SLE)– Drugs (AmphoB, Lithium)– Genetics

• Complications:– Nephrolithiasis & nephrocalcinosis

• Due to severe acidosis and its effect on bone mineral dissolution

• Treatment:– Correct K deficit prior to correcting acidosis– PO alkali therapy (1-2meq/kg daily) to neutralize acid

Type IV RTA• Not actually a disorder of the tubules

– Due to aldosterone deficiency/resistance in the distal tubules & collecting ducts• Affects Na/K ATPase -> hyperkalemia (decreased excretion)• Elevated potassium impairs NH4+ excretion into urine, thus left with NAGMA (less so than seen with Type

I RTA)

• Also have small +UAG• Causes:

– Diabetes Mellitus– Chronic Interstitial Nephritis– Meds (Aldactone, ACEI, NSAIDs, Trimethoprim)

• Treatment:– Correct underlying hyperkalemia (this should restore NH4+ excretion and fix acidosis)– Can try PO alkali therapy– Stop offending meds– Increase distal sodium delivery to stimulate K and H secretion

• Fludrocortisone if not hypertensive• Thiazide if HTN +/- loop diuretic (if GFR <30)

A 32-year-old man is brought to the emergency department after becoming disoriented, combative, and agitated earlier that day. He is accompanied by a friend, who states that the patient has a history of alcohol and drug abuse, including inhalants. On physical examination, the patient is uncooperative and slightly disoriented. Temperature is normal, blood pressure is 140/88 mm Hg, and pulse rate is 98/min. The remainder of the examination is normal.

Glc 110, Na 142, K 4.1, Cl 109, Bicarb 23, BUN 18, Serum Osm 320, Creat 1.1, serum ketones +, UA with trace glc and 4+ ketones, ABG: 7.4/44/92 on RA

Which of the following is the most likely cause of this patient’s clinical presentation?

1 2 3 4 5

20% 20% 20%20%20%1. Alcoholic ketoacidosis2. Diabetic ketoacidosis3. Ethylene glycol4. Isopropyl alcohol5. Toluene

Osmolar GapSerum Osm – [2(Na) + Glc/18 + BUN/2.8]

• Causes:– Alcohols

• Ethylene Glycol• Methanol• Isopropyl Alcohol• Acetone

– Sugars• Mannitol• Sorbitol

– Lipids• Hypertriglyceridemia

– Proteins• Hypergammaglobulinemia

A 35-year-old man comes for a follow-up evaluation for recurrent symptomatic calcium oxalate kidney stones. His episodes of nephrolithiasis are associated with significant pain and are disabling. His last attack was 1 month ago. He first developed kidney stones 5 years ago and typically has one to two episodes each year. He has been adherent to recommendations to increase his fluid intake and maintain a low-sodium diet.

On physical examination, vital signs are normal. BMI is 26. The remainder of the examination is unremarkable

Workup: UA: pH 5.0 (normal 6.5-8.0), 1+ blood, no protein, 0-3 RBCs/hpf, no bacteria, no glcUrine Ca excretion: 230mg/24h (nml 100-300mg/d)Urine citric acid excretion: 350mg/24h (nml 320-1240mg/d)Urine oxalate excretion: 140mg/24h (nml 9.7-40.5mg/d)

In addition to avoiding foods high in oxalate and adhering to a low-protein diet, which of the following is the most appropriate next step in this patient’s management?

1 2 3 4

25% 25%25%25%

1. Begin allopurinol2. Begin hydrochlorothiazide3. Begin sodium citrate4. Increase dietary calcium intake

A 56-year-old man comes for a follow-up examination. Two weeks ago, he was evaluated in the emergency department for acute flank pain caused by a passed uric acid stone; since then, he has been asymptomatic and has felt well. He believes he had a kidney stone 5 years ago but did not seek medical attention at that time. He has hypertension and a 3-year history of infrequent gouty attacks. His only medication is lisinopril.

On physical examination, temperature is normal, blood pressure is 132/80 mm Hg, pulse rate is 70/min, and respiration rate is 18/min. BMI is 21. The remainder of the examination is unremarkable.

Urinalysis shows a urine pH of 5.5, but no blood/protein.

In addition to increasing PO fluid intake, which of the following is the next best step in management of this patient?

1 2 3 4

25% 25%25%25%

1. Allopurinol2. Hydrochlorothiazide3. Potassium citrate4. Probenecid

Kidney Stones

~80%

~1-3%

~10%

~10%

Kidney Stones• Calcium Oxalate Stones (~80%)

– 3 mechanisms:• Hypercalciuria (**most common)

– **Need to increase Ca intake (binds Oxalate in gut and prevents its absorption)– thiazides

• Hyperoxaluria– **need to increase Ca intake– avoid high oxalate foods (rhubarb, peanuts, spinach, chocolate)

• Hypocitrauria (citrate normally binds Ca in urine and prevents it from binding oxalate– Need to increase citrate (lemon juice or potassium citrate)

• Uric Acid Stones (10%)– Seen in Gout, Tumor Lysis Syndrome– Treatment:

• Urine alkalinization (potassium citrate)• Allopurinol (after attempting to alkalinize urine)

• Struvite Stones (10%)– Increased risk with recurrent Klebsiella or Proteus UTI– Need to acidify urine!! (i.e. cranberry juice)– If not treated, can lead to Staghorn Calculi– If infected, need Abx and referral to urology

• Cysteine Stones (1-3%)– Often due to genetic defect leading to increased cysteine excretion– Tx: Alkalinization of urine

A 26-year-old man is evaluated in the emergency department for a 1-day history of acute abdominal pain that has progressively worsened. He has pain in the left flank that radiates to the groin. He also has nausea and vomiting. Ibuprofen has not provided relief. On physical examination, temperature is normal, blood pressure is 168/98 mm Hg, pulse rate is 100/min, and respiration rate is 18/min. BMI is 28. Abdominal examination reveals left costovertebral angle tenderness.

Serum creatinine 1.5Urinalysis: pH 5.0, 2+ blood, 1+ Leuk esterase, 2-5 WBC/hpf, 25-50 RBC/hpf, no bacteriaNoncontrasted CT of the abdomen reveals 4-mm calculus in the mid left ureter and mild hydronephrosis

In addition to analgesic, which of the following is the most appropriate management for this patient?

1 2 3 4

25% 25%25%25%

1. Extracorporeal shock-wave lithotripsy2. Intravenous cephalexin3. Intravenous saline4. Percutaneous nephrostomy

A 52-year-old woman is evaluated for dysuria, urinary frequency, and lower abdominal pain of 2 days’ duration. Medical history is significant for urinary tract infection that occurs three to four times yearly. She also has hypertension treated with amlodipine. On physical examination, temperature is 37.4 °C (99.3 °F), blood pressure is 152/96 mm Hg, pulse rate is 80/min, and respiration rate is 18/min. BMI is 41. The remainder of the examination is normal except for mild suprapubic tenderness

Labs: WBC 7,000; BUN 12; Creatinine 1.0; Urinalysis pH 8.0, 1+ blood; 3-5 RBC/hpf; leukocyte clumps, + leuk esterase, + nitrites. Abdominal CT reveals a 4-cm staghorn calculus on R kidney.

Which of the following is the most appropriate next step in this patient’s management?

1 2 3 4

25% 25%25%25%1. Extracorporeal shock-wave lithotripsy2. Intravenous cephalexin3. Percutaneous nephrolithotomy4. Start potassium citrate

Acute Management

of Kidney Stones

Lithotripsy (ESWL)• stones <1cm in kidney or

prox urinary tract (bust up the stones)

Ureterorenoscopy• scope into distal ureter to

remove stone (or parts of larger stone already broken up by ESWL)

Perc nephrolithotomy• For stones >1cm, any

staghorn or cysteine

Symptomatic Stone

Size of stone

5-7mm>7mm<5mm

HydrationAnalgesia

CCB/a-blocker/steroidsLocate stone

Distal Proximal

Pass

Fail to pass

ESWL +/- scopeOr

Perc Nephrolithotomy

Uretero-renoscopy

A 35-year-old woman is evaluated for a 1-month history of progressive bilateral lower-extremity edema. She was diagnosed with type 1 diabetes mellitus 10 years ago. At her last office visit 4 months ago, the urine albumin-creatinine ratio was 100 mg/g. Medications are enalapril, insulin glargine, insulin aspart, and low-dose aspirin. On physical examination, vital signs are normal except for a blood pressure of 162/90 mm Hg. Cardiopulmonary and funduscopic examinations are normal. There is 3+ pitting edema of the lower extremities to the level of the thighs bilaterally

Hgb A1c 7.1%, Albumin 3, Creat 1.1 Urinalysis 3+ protein; 2+ blood; 8-10 dysmorphic RBCs/hpf; 2-5 WBCs/hpf; few RBC castsUrine protein/creat ratio: 5.2mg/mgKidney ultrasound: R kidney 12.2cm, L kidney 12.7; no hydronephrosis and no kidney masses

Which of the following is the most appropriate next step in this patient’s management?

1 2 3 4

25% 25%25%25%1. Cystoscopy2. Kidney biopsy3. Spiral CT of the abdomen/pelvis4. Observation

A 28-year-old female graduate student with progressive chronic kidney disease due to IgA nephropathy and hypertension is evaluated in the office. She has fistulous Crohn disease for which she has undergone multiple abdominal surgeries, including distal ileum and proximal colon resection as well as a temporary ileostomy and subsequent ileocolic anastomosis. She has been referred to a nephrologist, nutritionist, and social worker and has discussed various methods of kidney replacement therapy, including the risks and benefits. She would prefer kidney transplantation. Medications are lisinopril, calcium acetate, and epoetin alfa. There is no family history of kidney disease. She has type O blood, and her mother and father have blood types B and A, respectively. She has no siblings.

On physical examination, temperature is 36.8 °C (98.2 °F), blood pressure is 130/78 mm Hg, pulse rate is 62/min, and respiration rate is 14/min. BMI is 24. Cardiopulmonary examination is normal. Estimated glomerular filtration rate is 23 mL/min/1.73 m2.

Which of the following is the most appropriate next step in this patient’s management?

1 2 3 4

25% 25%25%25%

1. Begin training for peritoneal dialysis2. Evaluate her father as a potential kidney donor3. Evaluate her mother as a potential kidney donor4. Plan placement of AV fistula

CKD

Stage GFR What to do?

1 >90 Try to slow disease progression

2 60-89 Estimate & try to slow disease progression

3 30-59 Eval & treat disease complications

4 15-29 Prep for RRT

5 <15 (or on HD) RRT

Common etiologies:• Diabetic: microalbuminuria -> clinical proteinuria -> worsening HTN -> decreased GFR• Glomerular Disease: Nephritic vs nephrotic• Tubulointerstitial disease (bland UA +/- protein, concentrating defect)

• Analgesics (NSAIDs), Lead, obstructive nephropathy/chronic reflux• Vascular disease

• Small vessel (SCD, HUS): hematuria, proteinuria• Medium vessel (HTN): slow progression• Large vessel (RAS)

• Cystic Disease• Transplanted Kidneys

• Chronic rejection, drug toxicity, recurrence of native disease

CKD – Associated Complications• Acidosis – Goal: to keep Bicarb 20-26• Uremia – need to be on low-protein diet• HTN – Goal: <130/80• Hyperparathyroidism• Anemia• Renal Osteodystrophy

A 33-year-old woman comes for follow-up examination for a left fibula fracture due to a fall 1 week ago. She has hypertension and stage 5 chronic kidney disease treated with hemodialysis. Medications are lisinopril, sevelamer, epoetin alfa, calcitriol, and kidney vitamins. Exam is normal except for an arteriovenous fistula in the left forearm and a cast on her left leg.

Labs: Hgb 10.3, Albumin 3.5, Phos 5.8, Ca 8.4, PTH 700, Alk phos 330

Which of the following is the most likely cause of this patient’s bone disease?

1 2 3 4

25% 25%25%25%1. Adynamic bone disease2. Avascular necrosis3. Osteoporosis4. Secondary hyperparathyroidism

The dreaded Calcium/Phosphorus balance

parathyroid

Intestines

KidneyBone

Liver

Cholecalciferol (D3)

Ergocalciferol (D2)25-hydroxyvitamin D (Calcidiol)

1,25-dihydroxyvitamin D (Calcitriol)

PTH

Increased absorptionof Ca and Phos

Increased osteoclast resorptionof Ca and Phos

Increased Ca resorption; decreased Ca excretionDecreased phos resorption; increased phos excretion

Decreased calcitriol

X

XX

XCKD: PTH, Phos, calcitriol

Decreased calcium

Hyperparathyroidism• Secondary Hyperparathyroidism

– Due to CKD in which PTH is ramped up due to low Ca or calcitriol levels– Also leads to hyperphosphatemia– Treatment:

• Calcitriol (1,25-dihydroxyvitamin D)– But be warned that this could further elevate Ca and Phos levels (by increasing gut absorption)

• Keep Ca and Phos wnl (maintain Ca x Phos <55 to avoid calciphylaxis)– Avoid phos in diet– Phos binders if necessary

• Calcimimetics (cinacalcet)– Only if patient on HD and elevated calcium levels– To enhance sensitivity of Ca-sensing receptor to Ca thus blocking further PTH secretion– Stop if PTH <150 to prevent adynamic bone disease

• Tertiary Hyperparathyroidism– Results if secondary hyperpara not treated– Independent secretion of PTH– Treatment: parathyroidectomy

A 59-year-old woman is evaluated for a 2-week history of right hip pain. She has chronic kidney disease treated with peritoneal dialysis. Medications are epoetin alfa, calcium acetate, calcitriol, and a multivitamin. She has no history of exposure to aluminum-containing medications. On physical examination, vital signs are normal. There is tenderness over the right lateral trochanter. Internal and external rotation of the hip elicit pain.

Labs: Phos 5.6, Ca 10.2, Alk phos 86, PTH 21, 1,25-dihydroxyvitamin D 52, 25-hydroxyvitamin D 15

Plan radiograph of the right hip shows diffuse osteopenia. An area of lucency is seen along the medial aspect of the femoral neck on the right side consistent with a stress fracture.

Which of the following is the most likely cause of this patient’s bone disease?

1 2 3 4

25% 25%25%25%1. Adynamic bone disease2. Beta2-microglobuin-associated amyloidosis3. Osteitis fibrosa cystica4. Osteomalacia

Renal Osteodystrophy• Osteitis Fibrosa Cystica

– Due to high bone turnover resulting from persistent secondary hyperparthyroidism• Elevated PTH, elevated Alk Phos, hyperphosphatemia, hypocalcemia, 1,25-dihydroxyvitamin D deficiency (secondary hyperpara)

– Xrays: subperiosteal bone reabsorption (esp phalanges, distal clavicles) and areas of sclerosis amidst areas of osteopenia (Rugger Jersey Spine)

• Can also see areas of rapid osteoclastic activity -> erosive lytic lesions (Brown tumors) that may mimic neoplastic lesions– Treatment: same as treating secondary hyperparathyroidism

• Osteomalacia– Low bone turnover disease characterized by increased unmineralized osteoid

• Due to Vitamin D deficiency and profound hypocalcemia

• Adynamic Bone Disease – Low-turnover (opposite of osteitis fibrosa cystica)– Thought to be due to functional hypoparathyroidism due to excess use of vitamin D supplements and/or calcium loading; or

after excess removal of functional parathyroid tissue after parathyroidectomy.– PTH <100, frequent fractures and bone pain– Treatment: discontinuation of Vitamin D analogs and Ca-based binders; stop cinacalcet when PTH <150

• Mixed Osteodystrophy – a mix of high and low bone turnover diseases• Osteoporosis

– Often difficult to discern from other osteodystrophies (esp Stage 3-5) – need bone biopsy to prove; use bisphosphonates carefully (renally excreted)

– DEXA still helpful in Stage 1-2 -> indications for bisphosphonate therapy should mimic general population• Amyloidosis (beta2-microglobulin associated amyloid)

– Deposition into bone can be seen esp in uremic patients who have been on HD for years– Xray: cystic bone lesions at the end of long bones

A 35-year-old woman with a history of stage 4 chronic kidney disease and hypertension caused by FSGS is evaluated for a 2-month history of fatigue. She has no shortness of breath, melena, or menorrhagia. Medications are lisinopril, low-dose aspirin, sevelamer, and furosemide.

On physical examination, vital signs are normal. There is conjunctival pallor. Abdominal examination is normal. A stool specimen is negative for occult blood.

Labs: Hgb 8.6, WBCs 5600, MCV 82, Retic count 0.5% of RBCs, Ferritin 25, Transferrin sat 8%, Vitamin B12 600, Folate 15, Creatinine 3.8

Which of the following is the most appropriate next step in this patient’s management?

1 2 3 4

25% 25%25%25%1. Begin epoetin alfa2. Begin iron3. Measure serum erythropoietin4. Schedule bone marrow examination

Anemia• In CKD, typically due to decreased Epo production

– Seen in stage 4 and 5• Anemia of CKD is diagnosis of EXCLUSION

– No role for measuring Epo levels• Erythropoietin-stimulating agents (ESAs)

– Indications: patients with CKD and Hgb <10 in which other causes of anemia have been excluded

– NKF-K/DOQI guidelines recommend maintaining Hgb 11-12 but not exceeding 13• Higher mortality rate, increased cerebrovascular and thrombotic events and

HTN– Need adequate iron stores (goal transferrin sat >20% and ferritin >100)