[Serum hyaluronic acid and phospholipase A2 in an arthritic population].

Serum hyaluronic acid (HA) and A2 phospholipase (A2PL) activity were measured by radioimmunoassay (Pharmacia) and using a specific phospholipid substrate respectively, as potential markers of osteoarthritic synovitis. With neither age, treatment nor sample time taken into consideration, the concentration of HA (micrograms/ml) was 585 +/- 1,054 in rheumatoid arthritis, 379 +/- 409 in knee osteoarthrosis, 272 +/- 384 in hip osteoarthrosis, 131 +/- 144 in low back pain and 44 +/- 23 in osteoporosis, with no significant difference between the groups. HA was nevertheless found to be significantly higher in knee osteoarthrosis patients than in normal controls, when samples were drawn at the same time of day. Physical exercise (pedalling), as well as 20 hours lying flat and an intra-articular injection of corticosteroids did not cause any significant variation in serum HA levels in knee osteoarthrosis patients, in contrast to 20 hours of rest in the controls. A2PL activity was significantly higher in osteoarthrosis patients than in the controls, decreased with rest and corticosteroids and was not dependent upon sample time.