Levels of Hormones in Plasma and in Synovial Fluid of Knee Joint of Patients with Rheumatoid Arthritis

Overview

Background.
Dysfunction of endocrine system is very likely one of the important risk factors involved in the pathogenesis of rheumatoid arthritis. The aim of the present study was to investigate the levels of selected hormones in plasma and in synovial fluid of knee joint of patients with rheumatoid arthritis or with osteoarthritis, which could affect the inflammatory processes.

Methods and Results.
Thirty nine patients with rheumatoid arthritis (22 females and 17 males) and 12 patients with osteoarthritis (6 females and 6 males) were investigated. Concentrations of the following hormones were determined in plasma and synovial fluids: cortisol, 17-beta-estradiol, progesterone, dehydroepiandrosterone, aldosterone, testosterone, prolactin, insulin and C-peptide by using radioimmunoassay kits. Increased levels of 17-beta-estradiol and insulin were found in patients with rheumatoid arthritis as compared to those with osteoarthritis. The plasma concentrations of other hormones under study were not significantly different in these groups of patients. Higher levels of 17-beta estradiol, progesterone and aldosterone were noted in inflammatory knee exudate of patients with rheumatoid arthritis. The levels of other hormones in exudates of patients with rheumatoid arthritis and those with osteoarthritis were not significantly different. The ratio of 17-beta estradiol / cortisol, 17-beta estradiol / testosterone and 17-beta estradiol / dehydroepiandrosterone showed increased proportions of estrogens over androgens or glucocorticoids in exudate from patients with rheumatoid arthritis.

Conclusions.
These results demonstrated that steroid and peptide hormones are transferred to synovial fluid of knee. The presence of insulin, C-peptide and aldosterone was described for the first time in synovial fluid. In patients with rheumatoid arthritis a predomination of the levels of proinflammatory estrogens over androgens was found in knee exudate. Also the levels of aldosterone and progesterone were elevated in inflammation knee exudate. This suggests that these hormones present in synovial fluid may affect the local rheumatoid inflammatory processes.

Key words:
steroid and peptidic hormones, synovial fluid, rheumatoid arthritis, osteoarthritis.