MedlinePlus Medical Encyclopedia: Antimitochondrial antibody

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Antimitochondrial antibody

Contents of this page:
Illustrations Definition How the test is performed How to prepare for the test How the test will feel	Why the test is performed Normal Values What abnormal results mean What the risks are Special considerations

Illustrations

Blood test

Definition Return to top

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

How the test is performed Return to top

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 Return to top

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:

infant test or procedure preparation (birth to 1 year)
toddler test or procedure preparation (1 to 3 years)
preschooler test or procedure preparation (3 to 6 years)
schoolage test or procedure preparation (6 to 12 years)
adolescent test or procedure preparation (12 to 18 years)

How the test will feel Return to top

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 Return to top

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 Return to top

Normally, there are no antibodies present.

What abnormal results mean Return to top

A positive test may indicate:

What the risks are Return to top

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 Return to top

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.

Update Date: 8/2/2003

Updated by: Lisa Christopher, M.D., Division of Rheumatology, Johns Hopkins Hospital, Baltimore, MD. Review provided by VeriMed Healthcare Network.

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