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ANA (anti-nuclear
antibodies) (Also see ANA tutorial and MLO review article)
This is an indirect fluorescent antibody test for the semi-quantitative
detection of antinuclear antibody in human serum. This test system
is to be used as an aid in the detection of antibodies associated
with systemic rheumatic disease.
Antinuclear antibody (ANA) is a general term used to describe autoantibodies
against various cell nuclear proteins. Early studies of these autoantibodies,
using immunofluorescent techniques, revealed a select few nuclear
protein specificities. Because of the high correlation of positive
ANA with systemic lupus erythematosus(SLE), a negative ANA is helpful
to exclude the disease given the right clinical history.
Although antibodies specific to DNA continue to show a high disease
correlation with SLE, a number of nuclear and cytoplasmic macromolecules
have also been detected and associated with other connective tissue
diseases. Some of these antibodies appear to have diagnostic and/or
prognostic significance in progressive systemic sclerosis, mixed
connective tissue disease, Sjogren's syndrome, polymyositis, and/or
rheumatoid arthritis. Because of these disease associations, ANA
testing is now recognized as a general screening tool for connective
tissue disease.
Limitations:
Diagnosis cannot be made on the basis of antinuclear antibody detection
alone. The physician must interpret these results inconjunction
with the patient's history and symptoms, the physical findings,
and other diagnostic procedures.
Treatment should not be initiated on the sole basis of a positive
test for antinuclear antibodies. Clinical indications, other laboratory
findings, and the physician's clinical impression must be considered
before any treatment is initiated.
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