Antimitochondrial antibody

Definition
This is a blood test that detects the presence of antibodies against mitochondria (a part of cells).

How the test is performed

Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test
Fasting may be required for up to 6 hours before the test (usually overnight).

For infants and children:
The preparation you can provide for this test depends on your child’s age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics:

How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

This test is primarily used when there are symptoms of liver or other organ damage, to confirm a medical diagnosis, or help to identify possible causes of tissue damage.

The antimitochondrial antibody test is positive in up to 94% of people with biliary Cirrhosis, and 25% of those with chronic active hepatic or iodophathic (of unknown cause) Cirrhosis. It is positive in less than 1% of normal people. Titers (blood levels) of more than 1:160 are generally found only in biliary Cirrhosis.

Antimitochondrial antibodies are helpful in distinguishing biliary (bile system) cirrhosis from liver problems due to obstruction outside of the liver, viral hepatitis, and alcoholic Cirrhosis.

Normal Values

Normally, there are no antibodies present.

What abnormal results mean

A positive test may indicate:

What the risks are

     
  • excessive bleeding  
  • fainting or feeling light-headed  
  • hematoma (blood accumulating under the skin)  
  • infection (a slight risk any time the skin is broken)  
  • multiple punctures to locate veins

Special considerations

Antimitochondrial antibodies are not organ specific. Mitochondria are very small structures within cells. The antigen that triggers antibody production appears to be a protein found inside mitochondria.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 7, 2012
by Mamikon Bozoyan, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.