How should I interpret the results of liver function tests?

Spencer D. Kroll, MD
Internal Medicine
Although the elevation of liver enzymes do not strictly represent liver function abnormalities, the interpretation of elevated ALT (alanine aminotransferase) and AST (aspartate aminotransferase) in conjunction with bilirubin levels can suggest a diagnosis. Although diagnosis is a complex process, some rough rules of thumb are:
  • Aminotransferase > 10x normal and Bilirubin <5 can be ischemic or toxic injury of the liver
  • Aminotransferase > 5X normal and Bilirubin 5-10 can be acute viral hepatitis
  • Aminotransferase > 5X normal and Bilirubin >10 can be biliary obstruction of the liver
  • Aminotransferases > 3X normal with a 2:1 ratio of AST to ALT and variable elevations of bilirubin can be alcoholic hepatitis.  

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