SOLUBLE URATE IN SERA AND SYNOVIAL-FLUIDS FROM PATIENTS WITH DIFFERENT JOINT DISORDERS

Objective: To evaluate simultaneous serum and synovial fluid (SF) urat e levels in various inflammatory and noninflammatory joint disorders a nd to correlate SF white blood cell (WBC) counts with serum and joint fluid urate levels. Methods: Sixty-three paired samples of sera and SF from 58 patients including 25 patients with inflammatory arthropathie s, 18 patients with gout and 15 patients with noninflammatory joint di sordes, were measured for urate concentrations by a UV enzymatic metho d. Results: In inflammatory arthropathies other than gout, urate conce ntrations in SF were significantly lower than in paired sera (p < 0.00 01). There was no difference between the SF and serum urate levels in noninflammatory arthropathies and in gout. In gout, however, SF urate occasionally were found to be considerably higher than in sera. This p henomenon was observed in fluids with massive amounts of monosodium ur ate crystals. There was no correlation between SF WBC counts and serum or SF urate levels in any of the disease groups studied. Conclusions: Serum and synovial fluid levels vary more than previously recognized SF urate levels tend to reflect serum levels in gout and noninflammato ry arthropathies but not in inflammatory joint disorders. Disturbed pu rine metabolism in inflammatory arthropathies may reflect a component in the pathophysiology of inflammation, The elevations of SF urate lev els seen in gout are unique for this disease and most likely reflect c rystal dissolution in joints.