Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (744 page)

Decreased In

   Drugs (e.g., barbiturates)

   Limitations

   Specimens should be protected from light and analyzed as soon as possible.

   Compounds that compete for binding sites on serum albumin contribute to lower serum bilirubin levels (e.g., penicillin, sulfisoxazole, acetylsalicylic acid).

   Day-to-day variations are 15–30% and increase an average of one- to two-fold with fasting up to 48 hours.

   Total bilirubin is 33% and 15% lower in African American men and women, respectively, compared to other racial/ethnic groups.

   Light exposure can decrease total bilirubin up to 50% per hour.

   Total serum bilirubin not a sensitive indicator of hepatic dysfunction; it may not reflect degree of liver damage. Must exceed 2.5 mg/dL to produce clinical jaundice; >5 mg/dL seldom occurs in uncomplicated hemolysis unless hepatobiliary disease is also present.

   Total bilirubin is generally less markedly increased in hepatocellular jaundice (<10 mg/dL) than in neoplastic obstructions (≤20 mg/dL) or intrahepatic cholestasis.

   In extrahepatic biliary obstruction, bilirubin may rise progressively to a plateau of 30–40 mg/dL (due in part to balance between renal excretion and diversion of bilirubin to other metabolites). Such a plateau tends not to occur in hepatocellular jaundice, and bilirubin may exceed 50 mg/dL (partly due to concomitant renal insufficiency and hemolysis).

   Concentrations are generally higher in obstruction due to carcinoma than due to stones.

   In viral hepatitis, higher serum bilirubin suggests more liver damage and longer clinical course.

   In acute alcoholic hepatitis, >5 mg/dL suggests a poor prognosis.