Antimitochondrial Antibody and Antimitochondrial M2 Antibody

Does this test have other names?

AMA, mitochondrial antibody, antimitochondrial M2 antibody

What is this test?

This test looks for substances called antimitochondrial antibody and antimitochondrial M2 antibody in your blood.

These substances are usually made by your body if you have a condition called primary biliary cirrhosis (PBC). PBC is the most common autoimmune disease that affects the liver. In autoimmune diseases, the immune system attacks organs or tissues in the body. Antimitochondrial antibody is found in nearly 19 in 20 people with PBC.

PBC causes damage to ducts in the liver that drain away fluid called bile. As a result bile builds up in the liver. This scars the liver. This scarring keeps the liver from working as it should. Over time, it causes liver failure.

PBC is especially common in middle-aged women. It often strikes along with other autoimmune diseases, especially Sjögren syndrome.

PBC is usually diagnosed and treated early in the course of the disease. This is good, because early treatment can slow down liver scarring. It delays liver failure.

Why do I need this test?

You may have this test if you have symptoms of PBC. Symptoms include:

General tiredness (fatigue)

Itching

Belly (abdominal) pain

Nausea

Poor appetite

Bone, muscle, and joint pain

Weight loss

Yellowing of the skin and the whites of the eyes, and dark urine (jaundice)

Dry eyes and mouth. These are symptoms of Sjögren syndrome.

Buildup of fluid in your ankles and abdomen

You may also have this test if your healthcare provider thinks you have hepatitis. Hepatitis is a swelling of the liver.

What other tests might I have along with this test?

Your healthcare provider may also order other tests to confirm that you have PBC. These tests include:

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

A normal result for this test is negative. This means that you don’t have any antibodies in your blood. If your test is positive, your provider may do more testing to find out the titer. Titer refers to the portion of the antibody in your blood.

If your results show a high titer, it may mean that you have PBC. Higher titer results may also be caused by:

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my test results?

Certain medicines can affect your results.

How do I get ready for this test?

You don’t need to prepare for this test. But be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don’t need a prescription and any illegal drugs you may use.