Many medications have been associated with elevated uric acid levels. Pyra zinamide and ethambutol are two anti tuberculous drugs that have been reported to induce hyperuricemia. Pyrazinamide is a strong urate retention agent, causing a greater than 80% reduction in renal clearance of uric acid at a 300-mg therapeutic daily dose. The metabolite pyrazinoic acid is oxidized by xanthine oxidase and is likely responsible for the hyperuricemic effect. Hyperuricemia has been reported in 43% to 100% of patients treated with pyrazinamide (alone or in combination).6,9 Furthermore, gouty attacks have been associated with patients taking pyrazinamide. Ethambutol can also cause hyperuricemia by decreasing renal uric acid clearance, but it does so less consistently and to a lesser degree than pyrazinamide.