The mitochondria create energy for the cells in your body to use. They’re critical to the normal functioning of all cells.
Antimitochondrial antibodies (AMAs) are an example of an autoimmune response that occurs when the body turns against its own cells, tissues, and organs. When this happens, the immune system attacks the body as though it were an infection.
The AMAs can attack the mitochondria, and the test looks for elevated levels of these antibodies in your blood. The test is most often used to detect an autoimmune condition known as primary biliary cirrhosis (PBC).
The condition known as PBC destroys the mitochondria in the small bile ducts of the liver. Damaged bile ducts affect the liver’s ability to get rid of toxins. This can cause scarring, or cirrhosis of the liver.
Symptoms of PBC include:
- yellowing of the skin, or jaundice
- pain in the upper right abdomen
- swelling, or edema of the hands and feet
- a buildup of fluid in the abdomen
- dry mouth and eyes
- itchy skin
An AMA test is used to help confirm a doctor’s clinical diagnosis of PBC. An abnormal AMA test alone is not enough to diagnose the disorder. If this should occur, your doctor may also order more tests, including:
- antinuclear antibodies (ANA): Some patients with PBC also test positive for these antibodies.
- transaminases: The enzymes, alanine transaminase and aspartate transaminase, are specific to the liver. Testing will look for elevated amounts which is usually a sign of liver disease.
- bilirubin: This is a substance that occurs when red blood cells break down. It’s excreted through urine and high amounts can indicate liver disease.
- albumin: This is a protein made in the liver and low levels are indicative of liver damage or disease.
- C-reactive protein: This test is often ordered to diagnose lupus or heart disease, but it’s also an indication of liver inflammation.
- smooth muscle antibodies (SMA): This test is usually administered alongside ANA tests and helps to diagnose hepatitis.
AMA testing can also be used to rule out PBC after elevated levels of alkaline phosphatase (ALP) are found during routine blood testing. Elevated ALP levels may be a sign of liver or gallbladder damage.
The AMA test is a blood test. A nurse or technician will draw your blood from a vein near your elbow or hand. This blood will be collected in a tube and sent to a lab for analysis.
Your doctor will contact you to explain your results when they become available.
You may experience some discomfort when the blood sample is drawn. There can be pain at the puncture site during or after the test. In general, the risks of a blood draw are minimal. Potential risks include:
- difficulty obtaining a sample, resulting in multiple needle sticks
- excessive bleeding at the needle site
- fainting as a result of blood loss
- accumulation of blood under the skin, known as a hematoma
- infection at the puncture site
No preparation is needed for this test.
Normal test results are negative for AMA. A positive AMA test means that antibodies are being made and they’re attacking the mitochondria of cells. These antibodies are just one part of an autoimmune state that the body is generating. T-cells are also stimulated in the case of PBC, and the inflammation caused by this autoimmune state damages the bile ducts in the liver. A positive AMA test typically means you have PBC. It basically is a signal to doctors that your body is in an inflammatory state.
However, some people have positive AMA tests without having PBC. Certain other types of liver or autoimmune diseases may also cause elevated AMA levels.
If you have a positive test, you will probably need additional testing to confirm your diagnosis. In particular, your doctor may order a liver biopsy to take a sample from the liver. Your doctor may also order a CT or MRI of your liver.