title: Is there an association between urolithiasis and Roux-en-y gastric bypass surgery?
abstract: OBJECTIVE
  Several studies have documented high incidence of urinary lithiasis after jejunoileal by-pass. Roux-en-y gastric bypass surgery (RYGB) is currently the most common bariatric procedure. Because of its difficult for absorption, RYGB has a potential risk to increase the incidence of lithiasis. This study was conducted in order to test the hypothesis that RYGB increases the incidence urolithiasis after 50% of excessive weight loss.
  
  
  METHODS
  We performed a retrospective cohort study to evaluate 58 patients who underwent RYGB at the Obesity Service at Santa Casa de Misericordia de Sao Paulo, between 2000 and 2005, with minimum follow-up of 10 and maximum of 72 months, after the procedure.
  
  
  RESULTS
  Forty-five (77.6%) patients had >or= 50% loss of weight excess. There was no difference between the frequency of urolithiasis before and after the procedure, and nephrolithiasis was observed after surgery in only one patient, however this had been detected before the procedure.
  
  
  CONCLUSIONS
  In the period studied, RYGB does not seem to affect the incidence of urolithiasis after weight reduction. This may be due to its smaller malabsorptive component as compared with jejunoileal "by-pass", thereby possibly not significantly influencing the oxalate metabolism.
authors.affiliation: Division of Urology, School of Medicine, Santa Casa de Sao Paulo, Sao Paulo, Brazil. andrecostamatos@yahoo.com.br
authors.forename: Andre
authors.initials: A
authors.lastname: Costa-Matos
authors.forename: Luiz R
authors.initials: LR
authors.lastname: Guidoni
authors.forename: Kepler A
authors.initials: KA
authors.lastname: Carvalho
authors.forename: Roni C
authors.initials: RC
authors.lastname: Fernandes
authors.forename: Marjo D
authors.initials: MD
authors.lastname: Perez
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery; D012189:Retrospective Studies; D052878:Urolithiasis / Q000209:etiology*; D055815:Young Adult