Smooth Muscle Antibody (SMA) Test
Reviewed
This test looks for smooth muscle antibodies (SMAs) in a sample of your blood. High levels of SMAs are usually a sign of a chronic liver condition called autoimmune hepatitis. The test is mainly used with other tests to help determine if autoimmune hepatitis could be the cause of liver damage.
Preparation and collection
You don't need any special preparations for an SMA test.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
- This test alone cannot diagnose autoimmune hepatitis; results must be interpreted alongside other tests.
- It is possible for autoimmune hepatitis to be caused by other autoantibodies that are not commonly tested, so a negative result does not completely rule out the condition.
What to do next
Your provider will review your SMA results along with other test results and may suggest a liver biopsy to confirm the diagnosis. Talk with your provider about what your results mean for your health.
Evidence source
U.S. National Library of Medicine: Smooth Muscle Antibody (SMA) Test