The study included 58 non-stone-forming adults, of whom 52 underwent laparoscopic Roux-en-Ysurgery and six had a biliopancreatic diversion-duodenal switch procedure. Researchers collected 24-hour urine specimens at six or more months after surgery. Oxalate excretion in these patients was with oxalate excretion in a group of stone formers and a group of normal individuals.
Of the 58 subjects, 43 (74%) had hyperoxaluria evident in at least one 24-hour urine collection and 15 (26%) had profound hyperoxaluria. The bariatric patients had significantly higher mean urinary oxalate excretion than the normal subjects and stone formers.