APPROACH TO AZOTEMIC PATIENTS

Florencio J. Pine, M.D.

Objective:

Aims to assist the students in learning the following:

Clinical implication of azotemia Gather and analyze the clinical data base for systemtic

and logical assessmemt of azotemic patients Differentiate types and causes of renal failure Differentiate between acute and chronic renal failure Importance of recognizing acute from chronic renal

failure Arrive at the diagnosis using the clinical data base and

judicious utilization of diagnostic tools

Contents

1. Review of the basic renal function, anatomy and physiology

2. Definition and cardinal manifestations of azotemia

3. Diagnostic tools, use and interpretation

4. Types, manifestations and differentiating parameters of renal failure

5. Algorithm

Functions of the Kidney

1. Maintains fluid balance2. Maintains electrolyte balance3. Maintains acid-base balance4. Excretes water/ toxic waste products5. Synthesizes hormones6. Regulates blood pressure7. Contributes in glucose metabolism8. Conserves substrates that can be reused by

the body

The Nephron

The Glomerulus

Transport Functions of the Anatomic Segment of the Nephron

Patterns of Adaptation

Azotemia

Definition: Retention of nitrogenous waste products

in the blood

Implication: Renal dysfunction

Phases:Asymptomatic

Uremic state

Cardinal Manifestations: Renal Dysfunction

Oliguria - urine output < 400-500cc/day

Anuria - urine output < 100cc/day

Polyuria - urine output >3L/day with intake of <3L/day

Uremia

Other manifestation- determined by underlying disease

Basic Screening Diagnostic Tools

CBC BUN/Creatinine Urinalysis

Diagnostic Tools: Common Complications

Na, K, Cl ABG Chest Xray ECG

Diagnostic Tools: Causes

1. Uric Acid

2. CPK

3. Urine GS/CS

4. Urine diagnostic indices

5. KUB UTZ

6. Plain KUB Xray

7. CT Stonogram

Urine Indices

Estimation of Renal Function

1. BUN

2. Serum Creatinine

3. Creatinine Clearance

4. Estimated Creatinine clearance

Cockroft-Gault Formula:

CrCl (ml/min)=(140-age)(weight) (0.85)if female

(72) (creatinine)

5. Nuclear GFR

Classification

Acute

Functional deterioration within hours to days/ weeks

Potentially reversible damage

Chronic

Functional deterioration w/in weeks to months/years

Irreversible nephron/s injury

Acute renal failure: Classification

Pre- renal: Physiologic disturbance Decreased perfusion Increased waste production

Intrinsic: Definite anatomic damage Glomerulonephritis

Acute tubular necrosis Acute tubulointerstitial nephritis

Acute intratubular obstruction

Post-renal: Obstruction in the drainage Both ureters Urinary bladder outlet

Acute renal failure: Classification

Pre-Renal: Most Common

Intra-Renal: Most Impact Large Vessel Disease Small Vessel/Glomerulus Ischemic/Toxic ATN Acute TIN

Post-renal: Demand Immediate Diagnosis and Treatment

Ischemic/Toxic ATN: >90% of intra-renal

Vulnerability factors: excretes numerous drugs and solutes ability to concentrate solutes hundred fold large surface area high rates of active transport of solutes and

O2 consumption relative hypoperfusion

“RIFLE” Criteria for ARF

Three severity grades Risk 1.5X SCr increase or UO<0.5mL/kg/hr for 6 hrs Injury 2.0X SCr increase or UO <0.5mL/kg.hr for 12 hrs Failure 3.0X SCr increase or UO<0.5mL/kg/hr for 24hrs or

oliguria for 12 hours

Two outcome measures Loss (i.e. need for RRT) ESRD (dialysis dependency at three months)

“RIFLE” Criteria for ARF

These gradings were found to have prognostic value

Modified criteria felt to be more useful for patient management

Modified R, I, F categories-changed to stages 1-3 L and E remain as outcomes

Acute Kidney Injury Network (AKIN) Staging

*Stage allocated is highest (worse) of either of the criteria

Stage Creatinine* change over baseline

Oliguria criteria*

1 +27uM or 1.5-2X increase <0.5mL/kg/hr for >6 hrs

2 2-3X increase <0.5mL/kg/hr for >12 hrs

3 >3X increase or <0.3mL/kg/hr for 24 hours or anuria for 12 hours

Laboratory Findings in ARF

Chronic Kidney Disease (CKD)

Definition presence of either kidney damage OR GFR <60ml/min / 1.73 m2 for >3mos

Kidney damage refers to the pathological abnormalities

OR

Markers of damage like abnormalities in blood, urine or imaging tests

K/DOQI Practice Guidelines 2002

K/DOQI Stages of CKD(Kidney Disese Outcome Quality Initiative)

Stage Description GFR (ml/min/1.73m2)

0

1

2

3

4

5

Increased risk

Kidney damage with normal

or high GFR

Mildly decreased GFR

Moderately decreased GFR

Severe GFR decline

Kidney failure

>90 with CKD risk

factors

>90

60-89

30-59

15-29

<15 dialysis

Causes of CKD- REDCOP Registry

1. Diabetes Mellitus (35%)

2. Chronic Glomerulonephritis (25%)

3. Hypertension (20%)

4. Chronic Pyelonephritis (6%)

5. Autosomal Dominant Polycystic Kidney Disease (2%)

6. Unknown (5%)

Natural History of Renal Disease

DM Nephropathy - usually progress to ESRD within 5 years from

detection of overt proteinuria

Glomerulonephritis - variable progression to ESRD from few months to 10 years, depending on etiology and histology

Nephrosclerosis and Interstitial Diseases - usually slow progression over 10 years

End Stage Renal Disease (ESRD)

DEFINITION

Residual renal function < 15ml/min Irreversible renal damage

End Stage Renal Disease (ESRD)

CLUES: Permanent Renal Damage

1.History

Uremic features >3mos

Markedly elevated BUN + creatinine without or minimal symptoms

Chronic skin changes of uremia

2. Evidence of renal osteodystrophy

3. Ultrasound changes

-small kidneys

-hyperechoic kidneys with loss of CMJ

End Stage Renal Disease (ESRD)

Philippine Estimate (REDCOP 2004)

- Incidence = 120 million population

- Prevalence= 60 million population

Worldwide Incidence: ↑ by 3.2 -7.6% per year

Clinical Abnormalities in Uremia

Fluid and electrolyte disturbance Endocrine – metabolic disturbances Neuromuscular disturbance Cardiovascular and pulmonary disturbance Dermatologic disturbances Gastrointestinal disturbances Hematologic and immunologic disturbances

Cutaneous Manifestations: Uremia

1. Uremic frost- white dust-like material2. Xerosis3. Changes in skin pigmentation4. Changes in skin appendages Onycodermal bands = crescents

5. Half- and –Half Nails Distal brown + normal or white portion

6. Bullous dermatosis7. Uremic pruritus8. Vascular renocutaneous syndromes - increased capillary fragility

PARAMETER ACUTE CHRONIC

History Previously normal

History of fluid/ blood loss

S/Sx of ineffective

circulating volume

Previously with renal

disease/ chronic

systemic disease

PE

VS

Skin

Appearance

(+) signs of reduced

circulating volume

No change

+ Acutely ill

Hypertension

(+)Pallor

(+)Chronic uremic skin changes

(+)Uremic reath

Chronically ill

Acute vs Chronic Renal Failure

Acute vs Chronic Renal Failure

PARAMETER ACUTE CHRONIC

Laboratory

Hgb/Hct

Ca

Phosphorus

S. Crea

Normal

Usually normal

Often normal

>1mg% per day

Usually low

Usually low

Often elevated

<0.5mg% per day

Ultrasound

Kidney Size

Echogenicity

CMJ

Cortical thickness

Normal to globularly enlarged

Hypoechoic to normal

Normal to blurred

Normal

Normal to small

Hyperechoic, heterogenous

Indisctinct

Thinned out

Algorithm

Renal Disease

Good Poor

Non-dialytic TX

Treat

Etiology

-

-

Treat

Treat

Acute Chronic

Treat RRT

+

+Etiology

Assess Function

Assess for Life Threatening Complications

Assess for Nature of Injury

Check for Acute Component

Treat