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