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Also known as: Mitochondrial Antibody
Formal name: Antimitochondrial Antibody and Antimitochondrial M2 Antibody
Related tests: Antineutrophil cytoplasmic antibody (ANCA), Liver/Kidney microsomal antibody, Alkaline phosphatase (ALP), Alanine aminotransferase (ALT), Liver panel, Smooth muscle antibody (SMA), Antinuclear antibody (ANA)

At a Glance

Why Get Tested?

To help diagnose primary biliary cirrhosis (PBC)

When to Get Tested?

When a doctor suspects that a person may have primary biliary cirrhosis

Sample Required?

A blood sample taken from a vein in your arm

The Test Sample

What is being tested?

This test measures whether antimitochondrial antibodies (AMA) are present in the blood. Moderate or high levels of AMA are strongly associated with primary biliary cirrhosis (PBC). PBC is an autoimmune disorder that causes inflammation and scarring of the bile ducts inside the liver, causing continual liver damage and blockage of the bile flow. It is found most frequently in women between the ages of 35 and 60. More than 90% of those affected by PBC will have high levels of antimitochondrial antibodies.

Increased AMA levels are seen much less often in autoimmune hepatitis, sclerosing cholangitis,  liver disease due to chronic inflammatory bowel disease, and bile duct obstruction.

There are nine types of AMA (M1 – M9) of which M2 and M9 are the most clinically valuable. The presence of the M2 type has been particularly evident in primary biliary cirrhosis, while the other antigen types may be found in other conditions.

In some laboratories, if testing for AMA is positive, then further tests for the M2 subtype is performed. Some laboratories have started to offer the AMA-M2 test instead of the AMA, and this tests for all types together.

How is the sample collected for testing?

A blood sample is taken by inserting a needle into a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

Ask a Laboratory Scientist

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.