ASMA – anti-smooth muscle autoantibodies Overview

  • This test and the ANA test are ordered when a doctor suspects that the patient has autoimmune hepatitis. They are usually ordered when a patient presents with symptoms such as fatigue and jaundice (yellowing of the skin and eyes) along with abnormal findings on liver tests (such as aspartate aminotransferase (AST) and/or bilirubin), results that may be found during routine blood tests.
  • ASMA and ANA are usually ordered following or sometimes with a variety of tests that are used to help diagnose and/or rule out other causes of liver injury. These causes can include infections (such as viral hepatitis), drugs, alcohol abuse, toxins, genetic conditions, metabolic conditions, and primary biliary cirrhosis.
  • An anti-actin test may be ordered instead of the ASMA (anti-smooth muscle autoantibodies) when the doctor wants to screen for autoimmune hepatitis. This test is relatively new. In some cases, it is taking the place of the ASMA test; in others it may be followed by an ASMA for confirmation. The ultimate clinical utility of the anti-actin test has yet to be established.
  • When significant amounts of ASMA and ANA are present in the blood, the most likely cause is autoimmune hepatitis. When both are present, then systemic lupus erythematosus can be essentially ruled out (ANA will be positive with lupus, but ASMA will not).
  • When anti-actin antibodies are present in significant quantities in a patient with clinical signs of autoimmune hepatitis, then it is likely that the patient has the condition. In most cases, if the anti-actin is positive, the ASMA will also be positive. Since actin is only one of several cytoskeleton proteins, it is possible for a person to have anti-smooth muscle antibodies even when the anti-actin test is negative.
Autoimmune Hepatitis

Autoimmune Hepatitis

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