Differentials
Prerenal azotemia
SIGNS / SYMPTOMS
History of gastrointestinal hemorrhage, lactulose-induced diarrhea or other gastrointestinal (GI) fluid losses, aggressive diuretic therapy, or large volume paracentesis without albumin.
INVESTIGATIONS
Therapeutic trial of intravenous albumin results in improvement in renal function.
Acute tubular necrosis - ischemic
SIGNS / SYMPTOMS
Underlying condition that causes hypotension, such as prolonged prerenal azotemia, hypovolemia resulting in hypotension, or sepsis; or ischemia due to vascular disease.
INVESTIGATIONS
Urine sodium generally >40 mEq/L. However, urine sodium can also be elevated secondary to diuretics, frequently used in patients with ascites.
Acute tubular necrosis - nephrotoxic
SIGNS / SYMPTOMS
History of recent use of nephrotoxic agents such as gentamicin or nonsteroidal anti-inflammatory drugs, or exposure to radiocontrast agents.
INVESTIGATIONS
Urine sodium generally >40 mEq/L. However, urinary sodium can also be elevated secondary to diuretics, frequently used in patients with cirrhosis with large volume ascites.
Obstructive renal nephropathy
SIGNS / SYMPTOMS
Symptoms depend on cause.
Acute obstruction, such as renal calculi or acute papillary necrosis, presents with severe pain and hematuria.
Chronic obstruction, such as prostatic hypertrophy, may be asymptomatic.
INVESTIGATIONS
Renal ultrasonography shows hydronephrosis and hydroureter.
Glomerulonephritis
SIGNS / SYMPTOMS
Particularly in the setting of cirrhosis due to hepatitis B or C.
INVESTIGATIONS
Proteinuria (>500 mg/dL).
Red blood cells and red cell casts in urine.
May have cryoglobulinemia if viral hepatitis.
Renal biopsy changes consistent with glomerulonephritis.
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