Hepatitis A Tests

Updated on 7/28/09

Diagnosis of hepatitis A and hepatitis E is largely dependent upon a comprehensive clinical history with particular attention given to risk factors and the physical exam. The patient history should focus on recent travel; exposure to food, water, or shellfish that may have been contaminated by sewage; sexual promiscuity or homosexual activity; intravenous drug use; the possibility of occupational exposure; or other environmental risk factors. Attention should also be given to the use of medications to ascertain if drugs or dietary supplements toxic to the liver may have been used.

A simple blood test can confirm the diagnosis by detecting antibodies to the virus in the bloodstream. One type of antibody may be detected for life in an individual who has had hepatitis A, and it is responsible for protection against future infections. Hepatitis E can also be diagnosed through the detection of antibodies in the blood; viral particles in stool can be analyzed for diagnosis as well.

Serum enzymes, such as alanine aminotransferase and aspartate aminotransferase, which are measured in a blood test, remain the most sensitive indicators of acute viral hepatitis. ALT and AST are the first enzymes to reveal abnormalities during the disease process and the last to normalize. They may reach levels 100 times the upper limits of normal. ALT is usually more abnormal than AST in the early and late stages of the disease.

Serum bilirubin-a byproduct of old red blood cells normally processed and removed from the bloodstream by the liver-at levels of 2.5 to 3.0 milligrams per deciliter or greater establishes the presence of the jaundice phase of hepatitis.