Smooth Muscle Antibody (SMA) Test Test
This test looks for smooth muscle antibodies (SMAs) in your blood. High levels are usually a sign of autoimmune hepatitis, a chronic liver condition.
What this test measures
This test measures the level of smooth muscle antibodies (SMAs) in your blood. SMAs are autoantibodies that attack the liver, causing swelling and damage.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
A positive SMA test means SMAs were found in your blood. High levels often mean you have type 1 autoimmune hepatitis, but other conditions like primary biliary cholangitis, mononucleosis, hepatitis C, or certain cancers can also cause somewhat high levels.
Frequently asked questions
What is an SMA test?
It is a blood test that looks for smooth muscle antibodies (SMAs), which are autoantibodies that attack the liver.
Why is an SMA test done?
It is mainly used with other tests to help find out if autoimmune hepatitis could be the cause of liver damage.
What does a positive SMA test mean?
A positive result means SMAs were found in your blood. High levels often mean you have type 1 autoimmune hepatitis, but other conditions can also cause high levels.
What does a negative SMA test mean?
A negative result means SMAs were not found. You are unlikely to have type 1 autoimmune hepatitis, but you could still have type 2 if anti-LKM-1 antibodies are present.
Can an SMA test alone diagnose autoimmune hepatitis?
No, the test cannot diagnose the disease by itself. Your provider will consider other test results and may suggest a liver biopsy to confirm.
Related lab tests
Sources
- MedlinePlus: Smooth Muscle Antibody (SMA) Test — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.