pediatrics
Juvenile Idiopathic Arthritis (JIA)
Diagnosis of JIA
Clinical evaluation Rheumatoid factor (RF), antinuclear antibodies (ANA), anticyclic citrullinated peptide (anti-CCP) antibodies, and HLA-B27 tests Juvenile idiopathic arthritis should be suspected in children with symptoms of arthritis, signs of iridocyclitis, generalized adenopathy, splenomegaly, or unexplained rash or prolonged fever, especially if quotidian. Diagnosis of JIA is primarily clinical. It is made when a chronic noninfectious arthritis lasting > 6 weeks has no other known cause. Patients with JIA should be tested for RF, anti-CCP antibodies, ANA, and HLA-B27 because these tests may be helpful in distinguishing between forms. The test for ANA should be done by immunofluorescence because other methods may result in false-negative results. In systemic JIA, RF and ANA are usually absent. In oligoarticular JIA, ANA are present in up to 75% of patients and RF is usually absent. In polyarticular JIA, RF usually is negative, but in some patients, mostly adolescent girls, it can be positive. HLA-B27 is present more commonly in enthesitis-related arthritis. In systemic JIA, laboratory abnormalities suggestive of systemic inflammation, such as elevated erythrocyte sedimentation rate (ESR), ferritin, and C-reactive protein, along with leukocytosis, anemia, and thrombocytosis are almost always present at diagnosis. To diagnose iridocyclitis, a slit-lamp examination should be done even in the absence of ocular symptoms. A recently diagnosed patient with oligoarticular or polyarticular JIA should have an eye examination every 3 months if ANA test results are positive and every 6 months if ANA test results are negative. 