Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (686 page)

   Hypothyroidism.

   Drug-induced injury to the liver.

   Acute bile duct obstruction due to a stone: Rapid rise of AST and ALT to very high levels (e.g., >600 U/L and often >2,000 U/L) followed by a sharp fall in 12–72 hours is said to be typical.

Decreased In

   Azotemia

   Chronic renal dialysis

   Pyridoxal phosphate deficiency states (e.g., malnutrition, pregnancy, alcoholic liver disease)

   Limitations

   Half-life of AST is 18 hours and that of ALT is 48 hours.

   The patient is rarely asymptomatic with ALT and AST levels >1,000 U/L.

   AST >10 times normal indicates acute hepatocellular injury, but lesser increases are nonspecific and may occur with virtually any form of liver injury.

   Increases ≤8 times upper limit of normal are nonspecific; may be found in any liver disorder.

   Rarely increased >500 U/L (usually <200 U/L) in posthepatic jaundice, AIDS, cirrhosis, and viral hepatitis.

   Usually <50 U/L in fatty liver.