Gastric Bypass Surgery May Increase Risk of Kidney Stones
Patients who undergo gastric bypass surgery experience changes in their urine composition that may increase their risk of kidney stone development, suggest investigators from the University of Texas Southwestern Medical Center at Dallas. Some of these urinary changes may be placing weight-loss surgery patients at higher risk for kidney stones compared with obese patients who do not undergo the procedure.
Researchers collected urine samples from 38 study participants, 16 women and three men in each of two groups. One group had undergone Roux-en-Y gastric bypass surgery, and the second group included normal obese individuals. As one of the most commonly performed weight-loss procedures, the surgery involves creating a small gastric pouch to allow food to bypass part of the small intestine.
In the study, the excretion of oxalate in the urine was significantly greater in participants who had the surgical procedure (47 percent) than those who did not (10.5 percent). In addition, the amount of a chemical called citrate in the urine was low in many gastric bypass patients (32 percent) compared with the obese nonsurgical group (5 percent). …