Because aminotransferases and alkaline phosphatase are included in commonly done laboratory test panels, abnormalities are often detected in patients without symptoms or signs of liver disease. In such patients, the physician should obtain a history of exposure to possible liver toxins, including alcohol, prescription and nonprescription drugs, herbal teas and remedies, and occupational or other chemical exposures.

Aminotransferases: Mild isolated elevations of ALT or AST (< 2 times normal) may require only repeat testing; they resolve in about one third of cases. If abnormalities are present in other laboratory tests, are severe, or persist on subsequent testing, further evaluation is indicated as follows:

• Fatty liver should be considered; it can often be recognized clinically (see Approach to the Patient With Liver Disease: Fatty Liver).
• Patients should be screened for hepatitis B and C (see Hepatitis: Serology).
• Patients > 40 should be screened for hemochromatosis (see Iron Overload: Hereditary Hemochromatosis).
• Patients < 30 should be screened for Wilson disease (see Mineral Deficiency and Toxicity: Wilson Disease).
• Most patients, especially young or middle-aged women, should be screened for autoimmune disorders.
• Patients at risk should be screened for malaria and schistosomiasis.

If at this point the results are negative, screening for α₁-antitrypsin deficiency (see Chronic Obstructive Pulmonary Disease and Related Disorders: α 1-Antitrypsin Deficiency) is indicated. If the entire evaluation reveals no cause, liver biopsy may be warranted.

Alkaline phosphatase: Isolated elevation of alkaline phosphatase levels in an asymptomatic patient requires confirmation of hepatic origin by showing elevation of 5´-nucleotidase or γ-glutamyl transpeptidase. If hepatic origin is confirmed, liver imaging, usually with ultrasonography or magnetic resonance cholangiopancreatography, is indicated. If no structural abnormality is found on imaging, intrahepatic cholestasis is possible and may be suggested by a history of exposure to drugs or toxins. Infiltrative diseases and liver metastases (eg, due to colon cancer) should also be considered. In women, antimitochondrial antibody should be obtained. Persistent unexplained elevations or suspicion of intrahepatic cholestasis warrants consideration of liver biopsy.

Last full review/revision September 2012 by Steven K. Herrine, MD

Content last modified November 2012