Serum levels of aspartate aminotransferase and alanine aminotransferase that exceed 1000 IU/L indicate acute viral hepatitis (A, B and, rarely, C), acute drug toxicity (eg, acetaminophen overdose or isoniazid hepatotoxicity), or ischemic liver injury. In chronic hepatitis (ie, hepatitis B or C or autoimmune), values range from mildly elevated to usually less than 400 IU/L. Elevated levels of al...