Antimitochondrial Antibody Test

Test Description

The antimitochondrial antibody (AMA) test is used to detect the presence of
autoimmune antibodies that have formed against a lipoprotein component of the
mitochondrial membrane. These antibodies have a tendency to attack organs that
expend a great deal of energy, such as those of the hepatobiliary system. The AMA
test is used in the diagnosis of primary biliary cirrhosis.

Normal Values

Negative at 1:20 dilution

A Possible Meanings of Abnormal Values
Increased
Cryptogenic cirrhosis
Drug-induced jaundice
Hepatic obstruction
Hepatitis
Primary biliary cirrhosis
Rheumatoid arthritis
Systemic lupus erythematosus

Contributing Factors to Abnormal Values
• Hemolysis of the blood sample may alter test results.

Interventions/Implications

Pretest
• Explain to the patient the purpose of the test and the need for a blood sample to be drawn.
• No fasting is required before the test.
Procedure
• A 7-mL blood sample is drawn in a red-top collection tube.
• Gloves are worn throughout the procedure.
Posttest
• Apply pressure at venipuncture site. Apply dressing, periodically assessing for continued
   bleeding.
• Label the specimen and transport it to the laboratory.
• Report abnormal findings to the primary care provider.

Clinical alert                           

• Prolonged bleeding from the venipuncture site due to vitamin K deficiency may
  occur secondary to liver dysfunction, as seen in severe hepatitis.
• The AMA test is usually performed in conjunction with the anti-smooth muscle
  antibody (ASMA) test.
• Interpretation of this test involves noting whether it is positive or negative; the

level of titer does not correspond to severity of disease or response to treatment.