A 15-year-old girl presented with knee pain, associated with a positive antinuclear antibody (ANA). She denied joint swelling or morning stiffness and remained physically active despite the pain. A physical examination was unremarkable except for articular hypermobility. Laboratory results were also unremarkable. Therefore, the positive ANA was determined to be nonspecific, and not concerning. In the evaluation of children with musculoskeletal complaints, unusual rash, or fatigue, an ANA assessment is frequently considered. When is this test most likely to be useful? What is the appropriate follow up for a positive result? Which results are concerning for an autoimmune process? This article reviews the literature to address these practical concerns. Understanding the indications for ordering an ANA, and the correct interpretation of a positive ANA, may reduce unnecessary referrals and costly tests. Moreover, the misperception that a positive ANA indicates a rheumatologic disease can cause significant patient and parental anxiety.
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