The synovial fluid components in long-term
hemodialysis patients (HD; 43 knees in 43 patients) were investigated and compared with those in patients with
osteoarthritis (OA; 21 knees in 21 patients) and
rheumatoid arthritis (RA; 26 knees in 26 patients). The average ages in the three groups were, respectively, 60.7 years (range, 34-79 years), 63.2 years (range, 48-88 years), and 59.7 years (range, 37-76 years). The duration of
hemodialysis in the HD group averaged 14.0 years (range, 4-24 years). The concentrations of
hyaluronic acid,
protein, and isomers of
chondroitin sulfate (
chondroitin 6-sulfate [C6S] and
chondroitin 4-sulfate [C4S]) in the synovial fluid, and its viscosity were measured. Differences in each of the parameters were investigated according to disease clinical stage, roentgenological grade, and periods of dialysis in the HD group. The viscosity of the synovial fluid and the concentration of
hyaluronic acid in HD patients were similar to those in OA patients; however, the C6S/C4S ratio in the synovial fluid of HD patients was similar to that in RA patients. The latter finding suggests that
synovitis may be present in the
hydrarthrosis of HD patients. The cause of this
synovitis in HD patients remains to be elucidated.