There is no single, definitive laboratory test for juvenile idiopathic arthritis, but some blood tests are helpful. A doctor diagnoses juvenile idiopathic arthritis based on the child's symptoms and the results of a physical examination. Iridocyclitis in juvenile idiopathic arthritis is asymptomatic , but it can lead to permanent loss of vision if untreated. Inflammation of the iris in the eye can develop with any type of juvenile idiopathic arthritis, but most often iridocyclitis develops with pauciarticular juvenile idiopathic arthritis or polyarthritis. Long-standing joint inflammation can eventually cause deformities or permanent damage of the affected joint. When juvenile idiopathic arthritis interferes with growth of the jaw, a small chin can result.
Joint deformities may develop if untreated. Any type of juvenile idiopathic arthritis can interfere with physical growth. Joint pain persists for years if untreated. Pain may become worse when the joint is moved.
