Diagnostic significance of increased serum hyaluronic acid in juvenile rheumatoid arthritis

Background: We have previously reported that serum levels of hyaluronic acid (HA) objectively reflect the severity of arthritis in juvenile rheumatoid arthritis (JRA). However, clear diagnostic standards do not exist for JRA; it is difficult to evaluate arthritis in children, particularly in small children and the diagnostic criteria for JRA requires an exclusion of several diseases. Therefore, if a specific test finding associated with JRA could be established, it would enable general pediatricians to make an objective diagnosis. Methods: We measured the serum HA levels in children with joint symptoms as a chief complaint. The total number of subjects were 197 children; of these 89 had JRA, 39 had rheumatic diseases other than JRA, and 69 had non-rheumatic diseases (including systemic 31, polyarticular 40 and pauci-articular in 17), rheumatic diseases other than JRA in 39 subjects, and non-rheumatic diseases in 69 subjects. Sandwich enzyme-linked immunosorbent assay measured HA by using the HA binding protein. Results: The serum level of HA was significantly higher in systemic and polyarticular JRA patients than in patients with pauci-articular JRA, with rheumatic diseases other than JRA, and non-rheumatic patients. With a cut-off value of 100 ng/mL, a diagnostic value of HA in all JRA patients was 48.3% sensitivity and 98.1% specificity. Conclusions: In children presenting with joint symptoms, serum HA measurement is useful for diagnosing systemic and polyarticular JRA.