AMA is non–organ specific and non–species specific and is directed against a lipoprotein in the inner mitochondrial membrane. AMA is a marker for PBC, a chronic inflammatory liver disease, characterized by the progressive destruction of interlobular bile ducts with development of cholestasis and, eventually, cirrhosis.
The mitochondrial antigens recognized by AMAs in patients’ sera have been classified as M1 through M9, with M2 recognized by AMAs in more than 90% of patients with PBC. The antibodies are predominantly IgG. This measurement aids in the diagnosis of PBC, a progressive disease most commonly seen in women in the second half of their reproductive years. There is also a genetic predisposition.
Negative: <1.0 U, by IFA
Positive: >1.0 U
If positive, serum is titered.
Reference values are in arbitrary units and will vary with method of testing.
Collect a 7-mL blood serum sample in a red-topped tube. Observe standard precautions. This amount is sufficient for both AMA and ASMA testing.
Label the specimen with the patient’s name, date, and test(s) ordered and place in a biohazard bag for transport to the laboratory.
Elevated concentrations of AMAs are present in more than 90% of patients with PBC.
High titers are also associated with long-standing hepatic obstruction, chronic hepatitis, and cryptogenic cirrhosis.
Elevated levels are occasionally present in the following conditions:
SLE
RA
Thyroid disease
Pernicious anemia
Idiopathic Addison disease
Pretest Patient Care
Explain test purpose and procedure.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan if needed. Immunofluorescence testing, along with quantitation of IgM and liver enzymes, both of which tend to be elevated in PBC, is reliable follow-up protocols.
Follow guidelines in Chapter 1 for safe, effective informed posttest care.