What is this test?
Anti-smooth muscle antibodies are the autoantibodies most commonly used as part of the evaluation for autoimmune hepatitis.
Why might it be ordered?
- In unexplained persistent elevation of liver enzymes.
- To complement ANA, IgG and other tests in suspected autoimmune liver disease.
What sample is needed?
A healthcare professional collects a venous blood sample. Depending on the method, the laboratory uses serum or plasma.
How should you prepare?
Tell the laboratory about all medicines, hormone treatments, vitamins and supplements you take. Do not stop or change treatment unless your clinician tells you to. Follow any instructions about fasting and the time of collection.
How should you understand the result?
A positive result supports clinical suspicion, but diagnosis may require other antibodies, imaging, and liver biopsy. A positive result means the tested antibodies were detected, but it does not establish a diagnosis on its own. A negative result does not rule out every autoimmune condition.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.