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.
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.
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.
In children presenting with joint symptoms, serum HA measurement is useful for diagnosing systemic and polyarticular JRA.