Changes in Urine Composition and Risk of Kidney Stone Disease Following Bariatric Surgery: A Systematic Review over Last 2 Decades

Purpose of Review The association of kidney stone disease (KSD) and gastrointestinal (GI) surgery has been well established. With a rising obesity crisis, we wanted to see the correlation of urinary composition in patients undergoing bariatric surgery and their risk of KSD. The objective of this paper is to perform a systematic review and meta-analysis of literature to evaluate the changes in urinary composition and risk of KSD following bariatric surgery. Recent Findings A total of seven studies (2498 patients) underwent bariatric surgery with a mean age of 46.7 years and a male:female ratio of 1:3. The most popular bariatric surgery was the Roux-en-Y procedure. Meta-analysis of the studies showed that significant decrease in urinary calcium, citrate, and urate, and increase in urinary oxalate. There was also a nonsignificant volume reduction in the post-operative cohort. The decrease in urinary citrate and increase in urinary oxalate are both predisposing factors of stone formation. Summary There is strong evidence that bariatric surgery results in significant changes in urine composition in keeping with the increased risk of developing KSD. This identifies useful therapeutic targets in the prophylactic management of patients who have undergone bariatric surgery.