Synovial fluid lipids in rheumatoid arthritis

Synovial fluid from the inflamed knee joints of 30 patients with rheumatoid arthritis (RA) contained 2.75 +/- 0.81 mmol/l cholesterol (51% of the corresponding mean serum level) and 0.32 +/- 0.13 mmol/l triglycerides (35% of the corresponding mean serum level). The ratio of synovial fluid triglycerides to cholesterol indicates that in RA the concentration of very low density lipoproteins (VLDL) is lower in synovial fluid than in serum. In a few patients, however, the "relative triglyceride concentration" in synovial fluid (i.e. synovial fluid tg/chol:serum tg/chol) was greater than 1. This concentration did not correlate, moreover, with the clinical activity of the disease.