Additional diagnostic studies in juvenile idiopathic arthritis are used selectively to evaluate complications, exclude alternative diagnoses, and monitor extra-articular involvement. These investigations are guided by clinical presentation and disease subtype and complement clinical assessment, laboratory testing, and imaging rather than serving as primary diagnostic tools.

In addition to clinical evaluation, laboratory testing, and imaging, other diagnostic studies may be used selectively in juvenile idiopathic arthritis (JIA) to assess disease activity, exclude alternative diagnoses, and evaluate complications.

• Slit-lamp examination to screen for chronic anterior uveitis
• Particularly important in ANA-positive oligoarticular and RF-negative polyarticular JIA
• May be asymptomatic and requires regular surveillance

• May be performed to exclude septic arthritis or crystal-induced disease
• Typically reveals inflammatory fluid with elevated leukocyte count
• Cultures are negative in JIA

• Considered when malignancy is suspected
• Useful in children with systemic symptoms, cytopenias, or atypical presentations
• Helps exclude leukemia or hemophagocytic disorders

• Echocardiography to assess for pericarditis or myocarditis
• Primarily indicated in systemic JIA with persistent fever or systemic inflammation

• Pulmonary function tests in patients with suspected lung involvement
• High-resolution CT may be considered for evaluation of interstitial lung disease in systemic JIA

These diagnostic studies are not routinely required for all patients and should be guided by clinical presentation, disease subtype, and suspected complications.

Chronic anterior uveitis associated with juvenile idiopathic arthritis can be detected by an experienced ophthalmologist using a slit lamp. Most children with JIA are enrolled in a regular slit lamp screening program

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<ref>Angeles-Han ST, Ringold S, Beukelman