What are the other Names for this Test? (Equivalent Terms)
- AMA (Anti-Mitochondrial Antibody) Test
- AMA Testing in Primary Biliary Cirrhosis
- Mitochondrial Antibody Test
What is Anti-Mitochondrial Antibody (AMA) Test? (Background Information)
- Anti-Mitochondrial Antibody Test measures the amount of anti-mitochondrial antibody (AMA) in blood
- The body produces certain proteins in blood, known as antibodies, to fight-off foreign invaders. Antibodies fight foreign invaders by creating immunity against the foreign microorganisms. In some individuals, the body starts producing antibodies against its own cells and tissues. Such antibodies are then termed as autoantibodies
- Anti-mitochondrial antibodies are autoantibodies that act against the mitochondria, located inside the cell. The mitochondria are responsible for producing energy inside the cells. An AMA positive test, strongly suggest the presence of autoimmune diseases
- Primary biliary cirrhosis (PBC) is one such autoimmune disease of the liver, in which AMA is positive in 90-95% of the cases. In PBC, the bile ducts inside the liver are affected. Bile ducts become inflamed and the occurrence of scars causes obstruction in the flow of bile, with progressive liver damage
- An AMA Test may also be positive with bile duct obstruction caused by other factors. These include primary and secondary sclerosing cholangitis
What are the Clinical Indications for performing the Anti-Mitochondrial Antibody (AMA) Test?
An Anti-Mitochondrial Antibody (AMA) Test may be ordered under the following conditions:
- If either the liver function tests are found to be abnormal during routine testing
- Or, if there are signs of liver damage (such as jaundice, enlarged liver, abdominal pain, itching, and fatigue)
- An AMA test may be ordered along with other tests and investigations, to either diagnose, or rule out autoimmune disorder, such as primary biliary cirrhosis
How is the Specimen Collected for Anti-Mitochondrial Antibody (AMA) Test?
Following is the specimen collection process for an Anti-Mitochondrial Antibody (AMA) Test:
Sample required: Blood
Process: Insertion of needle into the vein (arm).
Preparation required: No special preparation is needed, prior to the test.
What is the Significance of the Anti-Mitochondrial Antibody (AMA) Test Result?
The significance of the Anti-Mitochondrial Antibody (AMA) Test is:
- Generally, no antibodies are present in normal individuals
- 90-95% of individuals with primary biliary cirrhosis, test positive for anti-mitochondrial antibodies
- AMA Test may be positive with other autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, scleroderma, thyroiditis, etc.
- Lower levels of AMA may also be detected in some other liver diseases/conditions
In about 5-10% of the cases, individuals with primary biliary cirrhosis may have a negative AMA Test. Therefore, a negative test is likely to indicate the absence of PBC, but it does not completely rule out the condition. The healthcare provider makes a definitive diagnosis (and a choice of treatment) keeping in mind the results of the AMA Test along with the clinical signs and symptoms, the results from other lab tests and investigations.
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:
- At present, a total of 9 subtypes of mitochondrial antigens are recognized. These are denoted as M1 to M9. Out of these subtypes, M2 type of AMA is particularly recognized and detected, in cases of primary biliary cirrhosis
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.
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References and Information Sources used for the Article:
http://labtestsonline.org/understanding/analytes/ama/tab/test (accessed on 04/13/2014)
http://www.nlm.nih.gov/medlineplus/ency/article/003529.htm (accessed on 04/13/2014)