Antimitochondrial antibody

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Definition

Antimitochondrial antibodies (AMA) are substances (antibodies) that form against mitochondria. The mitochondria are an important part of cells. They are the energy source inside the cells. These help the cells work properly.

This article discusses the blood test used to measure the amount of AMA in the blood.

How the Test is Performed

A blood sample is needed. It is most often taken from a vein. The procedure is called a venipuncture.

How to Prepare for the Test

Your health care provider may tell you not to eat or drink anything for up to 6 hours before the test (most often overnight).

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 liver damage. This test is most often used to diagnose primary biliary cholangitis, formerly called primary biliary cirrhosis (PBC).

The test may also be used to tell the difference between bile system-related cirrhosis and liver problems due to other causes such as a blockage, viral hepatitis, or alcoholic cirrhosis.

Normal Results

Normally, there are no antibodies present.

What Abnormal Results Mean

This test is important for diagnosing PBC. Almost all people with the condition will test positive. It is rare that a person without the condition will have a positive result.

Rarely, abnormal results may also be found. This may occur due to other kinds of liver disease and some autoimmune diseases.

Risks

Risks for having blood drawn are slight but can include:

  • Excessive bleeding
  • Fainting or feeling lightheaded
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

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Blood test

References

Beuers U, Gershwin ME, Gish RG, et al. Changing nomenclature for PBC: From 'cirrhosis' to 'cholangitis'. Clin Res Hepatol Gastroenterol. 2015;39(5):e57-e59. PMID: 26433440 www.ncbi.nlm.nih.gov/pubmed/26433440.

Chernecky CC, Berger BJ. A. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:84-180.

Eaton JE, Lindor KD. Primary biliary cirrhosis. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 91.

Zhang J, Zhang W, Leung PS, et al. Ongoing activation of autoantigen-specific B cells in primary biliary cirrhosis. Hepatology. 2014;60(5):1708-1716. PMID: 25043065 www.ncbi.nlm.nih.gov/pubmed/25043065.

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