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Smooth Muscle Antibodies Blood Test

Last updated Oct. 12, 2015


What are the other Names for this Test? (Equivalent Terms)

  • ACTA Blood Test
  • ASMA Blood Test
  • F-Actin Antibody Blood Test 

What is Smooth Muscle Antibodies Blood Test? (Background Information)

  • Smooth muscle antibodies (SMA) are autoantibodies that target the body’s own smooth muscle tissue. Smooth muscles are present throughout the body, especially the in liver
  • Antibodies are circulating defense proteins. They are produced by a special form of white blood cell, called a plasma cell. Plasma cells are transformed versions of B lymphocytes, or B cells. They are antibody-producing factories
  • Antibodies target foreign invaders, such as cells, toxins, and microorganisms, and then clear these invaders from the body
  • Autoantibodies are malfunctioning antibodies that target native cells and tissue. They cause autoimmune diseases. A smooth muscle antibody is an example of an autoantibody
  • Smooth muscle antibodies target actin present in smooth muscle tissue. Actin plays a role in muscle contraction. Myosin, a motor protein, pulls on actin to cause muscle contraction
  • Smooth muscle antibodies cause type 1 autoimmune hepatitis. It can lead to liver cirrhosis and liver failure. There are 2 types of autoimmune hepatitis:
    • In type 1, the levels of smooth muscle antibodies are elevated
    • In type 2, the levels of another antibody, liver kidney microsomal type 1 (LKM-1), are elevated
  • The Smooth Muscle Antibodies Blood Test is a test to assess the levels of smooth muscle antibodies in blood. It is used to diagnose autoimmune hepatitis, as well as the specific type to which it belongs (either type 1 or type 2) 

What are the Clinical Indications for performing the Smooth Muscle Antibodies Blood Test?

Following are the clinical indications for performing a Smooth Muscle Antibodies Blood Test:

  • Yellowing of the skin and whites of the eyes
  • Nausea and vomiting
  • Fatigue
  • Loss of appetite
  • Dark-colored urine
  • Joint pain
  • Abdominal pain
  • Abnormal blood vessels are visible 

How is the Specimen Collected for Smooth Muscle Antibodies Blood Test?

Following is the specimen collection process for Smooth Muscle Antibodies Blood Test:

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: No special preparation is needed prior to the test. 

What is the Significance of the Smooth Muscle Antibodies Blood Test Result?

  • High levels of smooth muscle antibodies may indicate autoimmune hepatitis type 1 

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario. 

 Additional and Relevant Useful Information:

  • Certain conditions interfere with the results of the Smooth Muscle Antibodies Blood Test. These include infectious mononucleosis (also known as mono), hepatitis C, and certain cancers 

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis. 

What are some Useful Resources for Additional Information?

DoveMed is currently working to bring you additional resources.

Please sign up by creating a DoveMed account to receive periodic notification on information updates. 

References and Information Sources used for the Article:

Lab Tests Online (2013, September 26). Retrieved September 30, 2014 from http://labtestsonline.org/understanding/analytes/asma/

Martini, F., Nath, J. L., & Bartholomew, E. F. (2012). Fundamentals of anatomy & physiology (9th ed.). San Francisco: Benjamin Cummings.

Mayo Clinic. (2012, April 18). Autoimmune Hepatitis. Retrieved from http://www.mayoclinic.org/

Schnell, Z. B., Van, L. A., & Kranpitz, T. R. (2003). Davis's Comprehensive handbook of laboratory and diagnostic tests: With nursing implications. Philadelphia: F.A. Davis.

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Oct. 1, 2014
Last updated: Oct. 12, 2015