title: The longer-term effects of Roux-en-Y gastric bypass surgery on sodium excretion.
abstract: BACKGROUND
  Obesity is an independent risk factor for hypertension and chronic kidney disease. During the first months after bariatric surgery, an improvement of sodium excretion has been described. The aim of this work was to study the influence of bariatric surgery on sodium excretion at more than a year after the intervention.
  
  
  METHODS
  Patients who have undergone Roux-en-Y gastric bypass (RYGB) and who had collected a 24-h urine sample before surgery more than 12 months ago were asked to participate. A second 24-h urine sample was collected. Blood pressure and weight were measured. The difference in sodium excretion before and after surgery was calculated, and the relationship with blood pressure and weight loss was investigated.
  
  
  RESULTS
  We included 33 patients; the median follow-up time was 21 months (range 14-41). Sodium excretion was high before surgery (median 195 mmol/day, IQR range 167-247) and decreased by 18 % after surgery (median 160 mmol/day, IQR range 118-205, p = 0.015), while there were significant improvements in body weight (% EWL 80.9 ± 21.8), systolic blood pressure (126 to 120 mmHg, p = 0.02), and diastolic blood pressure (84 to 77 mmHg, p = 0.002), even with a reduced number of antihypertensive drugs.
  
  
  CONCLUSIONS
  After RYGB and considerable weight loss, sodium excretion remains high in the longer term. The profound improvement in blood pressure cannot be explained by reductions in sodium excretion after RYGB.
authors.affiliation: Department of Internal Medicine, Slotervaart Hospital, Louwesweg 6, 1066 EC, Amsterdam, The Netherlands. fundacelik170@hotmail.com
authors.forename: Funda
authors.initials: F
authors.lastname: Celik
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ahdi
authors.forename: Eelco W
authors.initials: EW
authors.lastname: Meesters
authors.forename: Arnold
authors.initials: A
authors.lastname: van de Laar
authors.forename: Dees P M
authors.initials: DP
authors.lastname: Brandjes
authors.forename: Victor E A
authors.initials: VE
authors.lastname: Gerdes
mesh_terms: D000328:Adult; D000419:Albuminuria / Q000652:urine*; D001794:Blood Pressure; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass / Q000379:methods; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000378:metabolism / Q000517:prevention & control; D010535:Laparoscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D009767:Obesity, Morbid / Q000453:epidemiology / Q000601:surgery / Q000652:urine*; D011184:Postoperative Period; D057234:Preoperative Period; D012307:Risk Factors; D012964:Sodium / Q000652:urine*; D013997:Time Factors; D015431:Weight Loss
chemical_list: D012964:Sodium