Because viral hepatitis and hepatitis caused by drugs have similar symptoms, tests for various autoantibodies help to distinguish autoimmune hepatitis. Autoimmune hepatitis is classified as either type I or II. Type I autoimmune hepatitis can occur at any age and is more common among women than men. Type II autoimmune hepatitis is less common, primarily affecting girls ages 2 to 14.

The autoantibodies associated with autoimmune hepatitis include:

• Antinuclear antibody (ANA)
• Anti–smooth muscle antibody (ASMA)
• Anti–liver-kidney microsomal antibody (LKM-1)

Antimitochondrial antibody (AMA) may be observed in the so-called overlap syndrome with autoimmune hepatitis.