Using the antinuclear antibody test to diagnose rheumatic diseases: when does a positive test warrant further investigation?

The anti-nuclear antibody (ANA) test is ordered commonly as a screening test for rheumatic diseases. Although ANA positivity is highly sensitive for certain rheumatic diseases, the presence of ANA is nonspecific and can be associated with numerous nonrheumatic factors, including environmental exposures, malignancies, drugs, and infections. This article describes a practical approach for physicians when evaluating patients using a positive ANA test. In the absence of connective tissue disease symptoms, the ANA test has minimal clinical significance in diagnosing rheumatic diseases. Understanding how to use ANA test results appropriately may reduce unnecessary referrals and costly workups.