Juvenile idiopathic arthritis
Juvenile idiopathic arthritis is arthritis beginning before age 16 and persisting at least 6 weeks with no other identifiable cause, spanning oligoarticular, polyarticular, systemic, enthesitis-related, and psoriatic subtypes. Diagnosis is clinical and antibody-subtyped; treatment starts with an NSAID and escalates through methotrexate to a biologic, while antinuclear-antibody-positive oligoarticular disease requires routine slit-lamp screening for silent chronic anterior uveitis.
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What this article covers
- Overview
Definition: juvenile idiopathic arthritis (JIA), formerly juvenile rheumatoid arthritis, is arthritis (joint swelling, or two of limited motion, tenderness, warmth) beginning before age 16 and…
- Epidemiology
Most common subtype: oligoarticular disease is the most frequent presentation, typically in young girls.
- Risk factors
Young female sex: the dominant demographic for oligoarticular and polyarticular disease.
- Pathophysiology
Chronic synovitis: immune-mediated inflammation of the synovium drives joint swelling, effusion, and progressive cartilage and bone injury if unchecked.
- Clinical features
Oligoarticular JIA: four or fewer joints, usually large and weight-bearing (knees, ankles); no systemic symptoms.
- Differential diagnosis
Acute lymphoblastic leukemia: leukocytosis, thrombocytosis, and lymphadenopathy can mimic systemic JIA, but marrow infiltration produces cytopenias and circulating blasts, not the cyclical fever and salmon rash of systemic disease.
- Diagnosis
The diagnosis is clinical: JIA is established by arthritis beginning before age 16 and persisting at least 6 weeks, with all other causes of childhood arthritis excluded; there is no single confirmatory test.
- Management
Start every subtype except systemic disease with an NSAID plus strengthening exercises: ibuprofen 5 to 10 mg/kg PO every 6 to 8 hours as needed, not exceeding 40 mg/kg/day, alongside physical and occupational therapy.
- Complications
Chronic anterior uveitis: silent, sight-threatening inflammation that can cause synechiae, cataract, glaucoma, and band keratopathy if screening is missed.
- Prognosis
Generally favorable: approximately 95% of JIA cases resolve by puberty; oligoarticular disease has the best long-term outlook when uveitis is caught early.
- Prevention
Schedule routine, not symptom-triggered, slit-lamp screening in every ANA-positive child, since chronic anterior uveitis in oligoarticular and ANA-positive polyarticular JIA is silent and otherwise goes undetected until damage occurs.
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