Effects of bariatric surgery on hyperuricemia and gout: a systematic review of the literature.

Gout is the most common form of inflammatory arthritis, and it is due to the deposition of monosodium urate crystals in the articular and extra-articular tissues. Body mass index is strongly correlated with elevated serum uric acid levels and gout is often associated with obesity and metabolic syndrome. Recommended nonpharmacological treatments for hyperuricemia and gout include dietary modifications and weight loss. Many studies have demonstrated that weight loss could reduce serum urate in patients with obesity and it is a commonly recommended treatment for gout. Bariatric surgery-induced weight loss exerts beneficial effects on hyperuricemia and gout, even if a possible raise of gout flares can be observed in patients with hyperuricemia early after surgery. The aim of this review is to systematically analyze all the studies published so far reporting a link between hyperuricemia and/or gout and bariatric surgery to obtain reliable figures on the incidence of this disease and describe the mechanisms underlying this association. Eleven studies accounting for 11,256 patients were included in the review. Mean preoperative prevalence of gout was 4.1%, while the preoperative prevalence of hyperuricemia ranged from 30.6% to 58%. After a mean follow-up of 8.5 months, postoperative prevalence of gout significantly decreased to 2.9% (p < .007). The incidence of gout flares after bariatric surgery was higher in the early postoperative phase and progressively decreased over time. Similarly, serum uric acid concentrations showed an increase within the first postoperative month, which was followed by a progressive decrease below the preoperative value.