Elevated plasma levels of hyaluronate in patients with osteoarthritis and rheumatoid arthritis.

Plasma levels of hyaluronate (HA) in patients with rheumatoid arthritis (RA) and patients with osteoarthritis (OA), measured by enzyme-linked immunosorbent assay, were compared with levels in a healthy, age-matched non-arthritic control group, in a retrospective study. Compared with the controls, the mean level of plasma HA was sevenfold higher in the RA group and twofold higher in the OA group. There was no statistically significant correlation between HA levels and 7 other clinical and biochemical parameters in patients with RA. In the OA group, however, plasma HA levels were found to correlate with an objective functional capacity score and with an articular index based on the total amount of cartilage in involved joints. In a retrospective longitudinal study of 6 patients with RA, plasma levels of HA did not show a significant correlation with plasma levels of elastase or with the erythrocyte sedimentation rate. These data support in part the contention that plasma HA may be unique as a marker, in that it may be a reflection of synovial involvement and inflammation, rather than only of inflammation, in arthritis.