Effect of urinary intestinal diversion on urinary risk factors for urolithiasis

We investigated the effect of urinary intestinal diversion on risk factors for calcium urolithiasis, such as calcium, phosphate, magnesium, uric acid, oxalate and citrate, in 3 groups of patients (Kock pouch, Indiana pouch and ileal conduit). Mean urinary volume was not significantly different among the 3 groups. Mean serum creatinine and 24-hour creatinine clearance in the continent reservoir group were better than in the ileal conduit group. Mean urinary excretion of calcium, phosphate and magnesium was significantly greater in the continent reservoir group than in the ileal conduit group. Although calcium excretion had a positive correlation with 24-hour creatinine clearance, calcium excretion per ml. per minute creatinine clearance still showed a significant difference. Increased calcium excretion is considered to reflect metabolic disturbances resulting from reabsorption of urinary solutes through the intestinal segments. Overall, there was no significant difference in the urinary parameters between the Kock and Indiana pouch groups. While mean urinary oxalate and citrate were within the normal range in all 3 groups, more than a third of the patients in each group were hypocitraturic (less than 100 mg. per day). In none of the 3 groups did the levels of urinary calcium, phosphate and magnesium, as well as other urinary risk parameters show any correlation with the duration of diversion. In summary, our study indicated that the continent urinary reservoir causes a long-term increase in urinary excretion of calcium, phosphate and magnesium. These urinary metabolic alterations might promote the formation of calcium urolithiasis as well as infectious stones. The degree of metabolic alterations may be greater with a continent reservoir than with an ileal conduit.