Anti-smooth muscle antibody

Definition

Anti-smooth muscle antibody is a blood test that detects the presence of antibodies against smooth muscle. The antibody is useful in making a diagnosis of autoimmune hepatitis.

How the Test is Performed

A blood sample is needed. This may be taken through a vein. The procedure is called a venipuncture.

How to Prepare for the Test

No special steps are needed to prepare for this test.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others may feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the Test is Performed

You may need this test if you have signs of certain liver diseases, such as hepatitis and cirrhosis. These conditions can trigger the body to form antibodies against smooth muscle.

Anti-smooth muscle antibodies are not often seen in diseases other than autoimmune hepatitis. Therefore, it is helpful to make the diagnosis. Autoimmune hepatitis is treated with immunosuppressive medicines. People with autoimmune hepatitis often have other autoantibodies. These include:

The diagnosis and management of autoimmune hepatitis may require a liver biopsy.

Normal Results

Normally, there are no antibodies present.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

A positive test may be due to:

The test also helps distinguish autoimmune hepatitis from systemic lupus erythematosus.

Risks

Risks associated with having blood drawn are slight, but may include:

References

Czaja AJ. Autoimmune hepatitis. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 90.

Ferri FF. Laboratory values and interpretation of results. In: Ferri FF, ed. Ferri's Best Test: A Practical Guide to Clinical Laboratory Medicine and Diagnostic Imaging. 5th ed. Philadelphia, PA: Elsevier; 2023:139-252.

Tanaka A. Autoimmune Hepatitis: 2019 Update. Gut Liver. 2020;14(4):430-438. doi: 10.5009/gnl19261. PMID: 32301319; PMCID: PMC7366136. www.ncbi.nlm.nih.gov/pmc/articles/PMC7366136/

Williams MJ, Gordon-Walker TT. Hepatology. In: Penman ID, Ralston SH, Strachan MWJ, Hobson RP, eds. Davidson's Principles and Practice of Medicine. 24th ed. Philadelphia, PA: Elsevier; 2023:chap 24.



Review Date: 1/25/2023
Reviewed By: Neil J. Gonter, MD, Assistant Professor of Medicine, Columbia University, NY and private practice specializing in Rheumatology at Rheumatology Associates of North Jersey, Teaneck, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
© 1997- adam.comAll rights reserved.
A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.