Turnover of a prostaglandin precursor, arachidonic acid, in rheumatoid arthritis.

The plasma concentration and the turnover of free arachidonic and oleic acids were determined in patients with rheumatoid arthritis and in control subjects. The plasma level of free arachidonic acid, but not of oleic acid, was significantly decreased in male rheumatoid patients. Female patients did not differ from healthy subjects in this respect. Following treatment with indomethacin, a significant increase in the plasma concentration of free arachidonic acid was observed in rheumatoid patients of both sexes. It is suggested that the findings in the rheumatoid patients reflect a partial exhaustion of the pool of arachidonic acid serving as precursor in the synthesis of prostaglandin.