title: Analysis of stone disease in morbidly obese patients undergoing gastric bypass surgery.
abstract: OBJECTIVE
  Recent studies have demonstrated a higher incidence of nephrolithiasis in the morbidly obese. Nephrolithiasis also has been described as a potential outcome after gastric bypass surgery. This is the first study to our knowledge that examines the incidence of nephrolithiasis in the morbidly obese in the setting of gastric bypass surgery at a tertiary referral center.
  
  
  METHODS
  We retrospectively reviewed the records of patients undergoing laparoscopic gastric Roux-en-Y bypass surgery for morbid obesity at our institution for the incidence of nephrolithiasis preoperatively, de novo stones postoperatively, and both preoperative and postoperative stone formation.
  
  
  RESULTS
  Of the 972 patients who underwent a laparoscopic gastric bypass for the treatment of morbid obesity between 1990 and the present, 85 (8.8%) were found to have upper urinary-tract calculi preoperatively, and 32 (3.2%) had de novo stones postoperatively. Of those 85 who had stones preoperatively, 26 (31.4%) developed recurrent stones postoperatively.
  
  
  CONCLUSIONS
  These results support findings in the current literature that nephrolithiasis has a higher incidence in the morbidly obese population. The combination of preoperative stone history and gastric bypass surgery may place patients at a higher risk of future stone formation. This latter group of patients should be screened for postoperative stone formation.
authors.affiliation: Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Omar
authors.initials: O
authors.lastname: Durrani
authors.forename: Shelby
authors.initials: S
authors.lastname: Morrisroe
authors.forename: Stephen
authors.initials: S
authors.lastname: Jackman
authors.forename: Timothy
authors.initials: T
authors.lastname: Averch
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D015390:Gastric Bypass; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D053040:Nephrolithiasis / Q000150:complications* / Q000453:epidemiology; D009767:Obesity, Morbid / Q000150:complications* / Q000453:epidemiology; D019990:Perioperative Care; D011184:Postoperative Period; D015995:Prevalence; D012008:Recurrence; D012189:Retrospective Studies