Description
Smooth Muscle Antibody with Reflex to Titer - Smooth muscle antibodies are detected in 85% of patients with chronic active hepatitis and in less than 50% of patients with primary biliary cirrhosis. Smooth muscle antibodies are usually negative in extrahepatic biliary obstruction, drug induced liver disease, viral hepatitis and hepatoma.
Smooth Muscle Antibody have been detected with an immunofluorescent assay that look for antibody binding to smooth muscle in tissue sections. The results were expressed as a titer which was the highest dilution of patient serum giving a positive result.
Anti-smooth muscle antibodies (ASMA) attack several of the structural proteins in smooth muscles which can affect the liver and other tissues. The presence of ASMA in the blood indicates that a person may have autoimmune hepatitis or another disease that can damage the liver.
Autoimmune hepatitis is an incomplete inflammation of the liver of unknown etiology that is associated with high concentrations of autoantibodies, pronounced hypergammaglobulinemia and the absence of cholestasis.
This can help in the differential diagnosis of liver disease. Antismooth muscle antibodies are found mainly in chronic active hepatitis. Antismooth muscle antibodies are also seen in acute viral hepatitis and low tiers can be seen in primary biliary cirrhosis. Smooth muscle antibodies (SMA) may be displayed in patients with acute and chronic hepatitis, with the highest titers occurring in chronic active hepatitis. SMA tests have been helpful in confirming the diagnosis of approximately 70% of the cases of chronic active hepatitis. A positive SMA test helps to rule out systemic lupus erythematosus,as this disease usually tests negative for SMA.
The definitive diagnosis requires the exclusion of viral, hereditary and drug induced liver disease.
