An AMA test is used to diagnose certain types of autoimmune disease, usually primary biliary cirrhosis, a type of liver disease. The “AMA” stands for antimitochondrial antibodies, a group of substances that form against the cell’s mitochondria. The test is ordered when a physician suspects primary biliary cirrhosis, based on symptoms or other indicators of the disease such as elevated liver enzymes found during another routine blood test.
The mitochondria are considered the “powerhouses” of the cells. Like the digestive system, they break down nutrients to adenosine triphosphate (ATP), an energy-carrying molecule that supplies necessary substances to perform all functions throughout the body. In simple terms, mitochondria are like power plants that create the electricity and ATP is the wire that carries the current into a home. Antimitochondrial antibodies attack at the power plant level, preventing the electricity from ever reaching vital areas.
There are nine different subtypes of antimitochondrial antibodies, labeled M1-M9. The AMA test measures all of them at the same time. An AMA-M2 test specifically measures that subtype, which is usually indicative of primary biliary cirrhosis. Physicians may order one or both tests at the same time. Low levels on an AMA test usually indicate something other than primary biliary cirrhosis, such as lupus or rheumatoid arthritis. The AMA test alone cannot be used to diagnose primary biliary cirrhosis; other tests are usually run in conjunction with it to rule out other causes of liver injury, such as drug or alcohol abuse, genetic conditions, or infections.
Primary biliary cirrhosis is a disease that slowly destroys the bile ducts of the liver. The body uses bile to digest fats and get rid of old blood cells, toxins, and cholesterol. When the bile ducts are destroyed, harmful substances build up in the blood stream, such as antimitochondrial antibodies. Early warning signs of the disease include fatigue, itching and dry eyes or mouth, but many patients experience no symptoms at all. The AMA test helps diagnose primary biliary disease, even in patients who are asymptomatic.
The AMA test is performed by inserting a needle into a vein, typically inside the elbow or on the back of the hand. The blood is collected into a vial and sent to a laboratory for analysis. Risks of the AMA test are the same as with any blood test. Some patients may feel faint during and after the test. In rare cases, excessive bleeding or infection can occur.