Type of test Blood

 Normal findings

 No antismooth muscle antibodies (ASMAs) at titers > 1:20

Test explanation and related physiology

 The ASMA is used primarily to aid in the diagnosis of auto immune chronic active hepatitis (CAH), which has also been referred to as lupoid CAH. ASMA is an anticytoplasmic antibody directed against actin, a cytoskeletal protein. Normally the serum does not contain ASMA at a titer greater than 1:20. ASMA is the most commonly recognized autoantibody in the setting of CAH. It appears in 70% to 80% of patients with CAH. Some types of CAH do not have positive ASMA antibodies.

ASMA is not specific for CAH and can be positive in patients with viral infections, malignancy, multiple sclerosis, primary biliary cirrhosis, and Mycoplasma infections. Usually the titer of ASMA is low in these diseases. With CAH, the titer is usually higher than 1 to 160. The titers are not helpful in prognosis nor do they indicate disease response to therapy.

Procedure and patient care

 • See inside front cover for Routine Blood Testing.

 • Fasting: no

 • Blood tube commonly used: red

 Abnormal findings

Increased levels

Chronic active hepatitis

 Mononucleosis hepatitis

 Primary biliary cirrhosis

 Viral hepatitis

Multiple sclerosis

Malignancy

 Intrinsic asthma