Antimitochondrial antibodies (AMA)
Antimitochondrial antibodies (AMAs) are autoantibodies that are commonly associated with primary biliary cholangitis (PBC), a liver disease. They are directed against the E2 subunits of the 2-oxo acid dehydrogenase complexes found in mitochondria. AMA testing is primarily used to diagnose PBC.
What they are:
- AMAs are antibodies that the body produces against its own cells, specifically against the mitochondria (the powerhouses of the cell).
Why they matter:
- In PBC, the immune system mistakenly targets the bile ducts in the liver, leading to inflammation and damage. AMAs are a key indicator of this autoimmune response.
How they are detected:
- An AMA test is a blood test that checks for the presence and amount of AMAs in a person's blood.
When they are ordered:
- An AMA test is usually ordered when a doctor suspects a patient might have PBC or another autoimmune disorder affecting the liver.
What the results mean:
- A positive AMA result indicates that the antibodies are present in the blood, which is strongly suggestive of PBC.
- A negative AMA result does not necessarily rule out PBC, as some individuals may have the condition without detectable AMAs.
Other uses:
- While most commonly associated with PBC, AMAs may also be found in other autoimmune diseases and in some cases of liver disease.
In summary, AMAs are a crucial diagnostic tool for PBC, a chronic liver disease characterized by an autoimmune attack on the bile ducts. They are detectable in a high percentage of PBC patients and can help confirm the diagnosis, even though a small percentage of patients with PBC may not have detectable AMAs.