Serum Urate During Acute Gout

Objective.To study the frequency of normal serum urate (SU) levels during acute gout in the largest studies of acute gout treatment to date.Methods.Data collected from 2 randomized controlled clinical trials assessing the efficacy of etoricoxib or indomethacin for 7 days in acute gout were used to assess SU levels during acute gouty attacks. Efficacy was similar with both agents, so both groups were combined for analysis.Results.A total of 339 patients were enrolled in the 2 studies; 94% were male; mean age was 50.5 years. At baseline, 14% of patients had a “true” normal SU (≤ 6 mg/dl) and 32% had SU ≤ 8 mg/dl during acute gout. Baseline mean SU was 7.1 versus 8.5 mg/dl (p < 0.001) in those taking allopurinol versus nonusers. Patients taking chronic allopurinol were more likely to have lower SU at baseline compared to those not taking chronic allopurinol (p < 0.001) during the acute attack.Conclusion.A normal SU level at presentation does not exclude an acute gouty attack. In the largest studies of acute gout to date, attacks still occurred despite SU levels being below 6.8 mg/dl, the saturation level for urate. This may be attributed to persistence of tophi and an increased body uric acid pool. Additional studies are needed to determine the correlation between SU and the body uric acid pool as well as the relationship to timing of changes during acute gout.