Prochaska M, Asplin J, Chapman A, et al. - Since a higher postsurgical risk of kidney stones is is linked to patients who undergo Roux-en-Y gastric bypass (RYGB), researchers studied 18 men and women prior to and post-RYGB, by analyzing their urine composition, to determine disparities in kidney stone risk. Pre- and post-RYGB urine collections were completed by seven men and 11 women. Higher calcium oxalate supersaturation (CaOx SS) was detected pre-RYGB in males vs females. Following RYGB, higher urine CaOx SS, calcium phosphate supersaturation, and lower urine volumes were seen in females vs males. Overall, urine composition demonstrated crucial differences by gender that may add to higher renal stone risk in females post-RYGB vs males.