Urolithiasis in patients with a jejunoileal bypass

517 patients who had a jejunoileal bypass were studied with regard to the jformation of urinary calculi postoperatively. A 9% incidence of stones was found in the 365 patients for whom complete data were available. Men were affected more commonly than women. Of particular note was the correlation between long term oral supplementation of calcium postoperatively and a delay in the onset of symptomatic urolithiasis. A group of 91 recent patients who have been maintained on orally administered calcium are stone-free as long as 12 months after operation, again suggesting that supplementation of calcium may help prevent urolithiasis in patients who have had a bypass procedure.