The effects of age and sex on chondroitin sulfates in normal synovial fluid

Abstract

To examine how age and sex influence chondroitin sulfates (CS) in normal synovial fluid, we measured the concentrations of chondroitin 6-sulfate (C6S), chondroitin 4-sulfate (C4S), and hyaluronic acid (HA) in healthy subjects of different ages. Synovial fluid samples were obtained from 82 healthy volunteers, ages 20-79 years. The concentrations of CS and HA and the C6S:C4S ratio varied with age. Their values were highest between 20 and 30 years of age, and thereafter they showed a tendency to decrease. Statistically, the C6S concentration and the C6S:C4S ratio at ages 60-70 years were significantly lower than those at 20-30 years of age. There was also a clear between-sex difference, in which the CS concentrations and the C6S:C4S ratio in women were significantly lower than those in men (P = 0.0003 for C6S, P = 0.02 for C4S, P = 0.002 for C6S:C4S ratio). In sharp contrast, little between-sex difference was found in the HA concentration. In multiple regression analysis, age correlated strongly with the C6S concentration and the C6S:C4S ratio (r = -0.521 and r = -0.617, respectively), weakly with the C4S concentration (r = -0.202), and moderately with the HA concentration (r = -0.483). Sex showed a weak correlation with the concentrations of C6S and C4S and the C6S:C4S ratio (r = 0.307, r = 0.225, and r = 0.237, respectively), and little correlation was seen between sex and the HA concentration. The CS concentrations and the sulfation patterns in normal synovial fluid vary with age and sex, and these physiologic variations need to be taken into account when using synovial fluid CS as markers for arthritic conditions.