What is Anti Mitochondrial Antibody (Qualitative)?
Also Known As:
Antimitochondrial Antibody and Antimitochondrial M2 Antibody
Antimitochondrial antibodies (AMA) are autoantibodies that are strongly associated with primary biliary cholangitis (PBC), formerly called primary biliary cirrhosis. This test detects and measures the amount (titer) of AMA in the blood.
Primary biliary cholangitis is a chronic autoimmune disorder that causes inflammation and scarring of the bile ducts inside the liver. It is a slow-progressing disease that causes worsening liver destruction and blockage of the bile flow. Blocked bile ducts can lead to a build-up of harmful substances within the liver and may eventually lead to permanent scarring (cirrhosis). PBC is found most frequently in women between the ages of 35 and 60. About 90-95% of those affected by PBC will have significant titers of antimitochondrial antibodies.
AMA are autoantibodies that develop against antigens within the body. There are nine types of AMA antigens (M1 – M9) of which M2 and M9 are the most likely to cause illness (clinically significant). The presence of the M2 type of AMA has been particularly evident in PBC, while the other types may be found in other conditions. Some laboratories offer the AMA-M2 as a more specific test for PBC.
For more information on PBC, see the links in the Related Content section.
How is the test used?
The antimitochondrial antibody (AMA) test or the AMA-M2 test may be ordered to help diagnose primary biliary cholangitis (PBC).
Other tests that may be ordered include:
- Smooth muscle antibodies (SMA)
- Antinuclear antibodies (ANA)
- Alkaline phosphatase (ALP)
- IgM level
- Prothrombin time (PT)
- C-reactive protein (CRP)
These tests often help detect PBC, distinguishing it from other autoimmune conditions causing liver damage, and may be useful in helping to predict whether a person may need a liver transplant.
When is it ordered?
The AMA or AMA-M2 test is ordered when a healthcare practitioner suspects that someone has an autoimmune disorder such as PBC that is affecting the liver. A person may have symptoms that include:
- Itching (pruritus)
- Abdominal pain
- Enlarged liver
Many of those affected with early PBC do not have any symptoms. The condition is often initially identified because a person has abnormal results on a liver panel (elevated liver enzymes), especially alkaline phosphatase (ALP).
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.