Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (535 page)

   Type III (pauci-immune RPGN): glomerulonephritis is associated with few or no immune deposits by immunofluorescence or electron microscopy (50% of cases; up to 90% of patients are ANCA positive).

   Laboratory Findings

Laboratory workup is urgent to initiate therapy since untreated patients progress rapidly to ESRD. Renal biopsy findings establish the diagnosis and prognosis.

   
Urinalysis

   Oliguria, with urine volume often <400 mL/day.

   Gross hematuria: RBCs, WBCs, RBC casts.

   Proteinuria starts approximately 3 days after injury and may not be marked because of the severe reduction in GFR.

   Rapid, progressive rise in creatinine and BUN.

   Laboratory tests to determine underlying etiology (e.g., ANCA, anti-GBM antibodies, antinuclear antibodies) can be helpful. Other tests include serology testing for HIV and hepatitis B and C.

HEPATORENAL SYNDROME

   Definition

   Progressive renal failure that develops in patients with decompensated liver cirrhosis or fulminant hepatic failure.

   Classified as

   Type I: serum creatinine increases to >2.5 mg/dL within 2 weeks

   Type II: less severe and associated with gradual increase in serum creatinine (1.5–2.5 mg/dL) over few weeks or months