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AMA

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 PBC

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

The Test Sample

What is being tested?

This test measures the amount of antimitochondrial antibodies (AMA) present in the blood. The increased production of AMA is 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 progressive hepatic destruction 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 significant concentrations of antimitochondrial antibodies.

Increased AMA levels are also seen in primary and secondary sclerosing cholangitis, liver disease due to chronic inflammatory bowel disease, and bile duct obstruction. In addition, elevated serum alkaline phosphatase levels can also be present.

There are nine types of AMA antigens (M1 – M9) of which M2 and M9 are the most clinically significant. The presence of the M2 type has been particularly evident in PBC, while the other antigen types may be found in other conditions. Some laboratories have started to offer the AMA-M2 instead of the AMA, which tests for all types together.

For more information on PBC and primary sclerosing cholangitis, click on the Links tab and see related links listed under Elsewhere on the Web.

How is the sample collected for testing?

A blood sample is obtained 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

How is it used?

The AMA test is ordered to help diagnose primary biliary cirrhosis (PBC). PBC is a serious condition in which the biliary system in the liver is gradually destroyed. (For more about this disease, see the links listed under Elsewhere on the Web).

Other tests that may be ordered include:

These tests often help detect PBC, distinguishing it from other autoimmune conditions causing liver damage, and may be useful predictors of need for a liver transplant.

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When is it ordered?

The AMA or AMA-M2 test is ordered when your doctor suspects that you have an autoimmune disorder such as PBC. You may have symptoms such as an enlarged liver and spleen, fatigue, jaundice, and itchiness, but many patients affected with early PBC do not have any symptoms. The condition is often initially identified because a patient has elevated liver enzymes, especially alkaline phosphatase (ALP), that are found during routine blood tests.

An AMA or AMA-M2 test may be ordered along with or following a variety of tests that are used to help diagnose and/or rule out other causes of liver disease or injury. These causes can include infections, such as viral hepatitis, drugs, alcohol abuse, toxins, genetic conditions, metabolic conditions, and autoimmune hepatitis.

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What does the test result mean?

Looking for reference ranges?

When significant amounts of AMA or AMA-M2 are present in the blood, the most likely cause is PBC. Low levels of AMA may also be present in patients with chronic active hepatitis, autoimmune hepatitis, liver or bile obstruction, and with infections such as syphilis or acute infectious hepatitis. It may also be present in patients with other autoimmune disorders such as systemic lupus erythematosus, rheumatoid arthritis, Sjogren syndrome, scleroderma, and thyroiditis.

Levels of AMA may be lower in children and in those with compromised immune systems. The level of AMA is not related to the severity of PBC symptoms or to a patient’s prognosis.

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Is there anything else I should know?

By themselves, AMA and AMA-M2 are not diagnostic of PBC, but in conjunction with other laboratory tests and clinical symptoms, the diagnosis of PBC can be made. When significant levels of AMA or AMA-M2 are present and the doctor suspects PBC, a liver biopsy may be performed to look for characteristic signs of primary biliary cirrhosis in the liver tissue. Imaging scans of the liver may also be ordered to look for bile duct obstructions.

About 50% of the cases of PBC will be discovered before the patient has noticeable symptoms.

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Common Questions

1.  What causes primary biliary cirrhosis (PBC)?

The cause is currently not known. It is not infectious and not inherited, although an increased susceptibility to develop autoimmune disorders may occur in some families. It can occur in anyone at any age, but it is primarily seen in middle-aged women.

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2.  How fast does PBC progress?

The course and severity of PBC is difficult to predict. Many patients will have no or few symptoms for many years. For more information, consult with your doctor and see the related links.

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Article Sources

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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.

Sources Used in Current Review

Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 85-86.

Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 272.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition: Saunders Elsevier, St. Louis, MO. Pp 746.

Dugdale, D. (Updated 2008 November 2). Autoimmune liver disease panel. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003328.htm. Accessed 1/29/09.

Christopher-Stine, L. (Updated 2006 August 22). Systemic lupus erythematosus. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000435.htm. Accessed 1/29/09.

Lehrer, J (2006 July 25 Updated). Autoimmune hepatitis. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000245.htm. Accessed 1/29/09.

Stone, C. (2008 May 20, Updated). Primary biliary cirrhosis. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000282.htm. Accessed 1/29/09.

Hill, H. (Updated 2008 September). Primary Biliary Cirrhosis. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/AutoimmuneDz/PBC.html# through http://www.arupconsult.com. Accessed 1/29/09.

Bylund DJ, Nakamura RM. Organ-specific autoimmune diseases. Henry’s Clinical Diagnosis and Laboratory Management, 21st ed., 2007. Pp 945-960.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO. Pp 82-83.

Lindor, K. (© 2002-2003) What is Primary Biliary Cirrhosis (PBC)? American Liver Foundation [On-line information]. Available online at http://www.liverfoundation.org/db/articles/1014 through http://www.liverfoundation.org.

(© 1995-2005). Primary Biliary Cirrhosis. The Merck Manual of Medical Information – Second Home Edition [On-line information]. Available online at http://www.merck.com/mmhe/print/sec10/ch136/ch136d.html through http://www.merck.com.

(© 1995-2005). Primary Sclerosing Cholangitis. The Merck Manual of Medical Information – Second Home Edition [On-line information]. Available online at http://www.merck.com/mmhe/sec10/ch136/ch136e.html through http://www.merck.com.

(© 2005). Mitochondrial M2 Antibody, IgG (ELISA). ARUP's Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.arup-lab.com/guides/clt/tests/clt_a89b.jsp#1142095 through http://www.arup-lab.com.

Beuers, U. and Rust, C. (2005 October 27). Overlap Syndromes. Medscape, from Semin Liver Dis. 2005; 25(3): 311-320. [On-line information]. Available online at http://www.medscape.com/viewarticle/512463 through http://www.medscape.com.

Stone, C. (2004 November 10, Updated). Autoimmune liver disease panel. Medline Plus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003328.htm.

Stone, C. (2004 May 14). Primary biliary cirrhosis. Medline Plus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000282.htm.

Peng, S. (2005 April 20). Antimitochondrial antibody. Medline Plus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003529.htm.

(© 2003). Mitochondrial (M2) Antibody. LabCorp [On-line test information]. Available online at http://www.labcorp.com/datasets/labcorp/html/chapter/mono/se000750.htm through http://www.labcorp.com.