title: Vitamin D absorption: consequences of gastric bypass surgery.
abstract: BACKGROUND
  Severe vitamin D deficiency is a common finding in morbid obesity, and the incidence increases markedly after RYGB. Normalization of vitamin D levels after RYGB is difficult to achieve because the degree of surgery-induced malabsorption is not known.
  
  
  OBJECTIVE
  To develop a test that quantifies the changes in intestinal cholecalciferol absorption induced by Roux-en-Y gastric bypass (RYGB) surgery.
  
  
  METHODS
  Absorption characteristics of cholecalciferol were studied in 14 morbidly obese, premenopausal women before and 4 weeks after laparoscopic RYGB. Serum cholecalciferol levels were measured at baseline and 1, 2, 3, and 14 days after a single oral dose of 50 000 IU solubilized cholecalciferol.
  
  
  RESULTS
  Peak serum cholecalciferol levels were observed on day 1 in all patients. They were 26.6±3.7% lower after RYGB (P=0.02). Inter-individual variability was high.
  
  
  CONCLUSIONS
  Peak cholecalciferol levels are reduced by about 25% after RYGB. Further analysis suggested that the timing of sampling in the current study was not optimal. This might have caused an underestimation of the true decrease in cholecalciferol absorption induced by RYGB.
authors.affiliation: Department of Surgery Internal Medicine, Rijnstate Hospital, The Netherlands.
authors.forename: Edo
authors.initials: E
authors.lastname: Aarts
authors.forename: Lenneke
authors.initials: L
authors.lastname: van Groningen
authors.forename: Ronald
authors.initials: R
authors.lastname: Horst
authors.forename: Darryl
authors.initials: D
authors.lastname: Telting
authors.forename: Adriaan
authors.initials: A
authors.lastname: van Sorge
authors.forename: Ignace
authors.initials: I
authors.lastname: Janssen
authors.forename: Hans
authors.initials: H
authors.lastname: de Boer
mesh_terms: D000328:Adult; D002762:Cholecalciferol / Q000627:therapeutic use; D005260:Female; D015390:Gastric Bypass / Q000009:adverse effects*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects / Q000502:physiology*; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000601:surgery*; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000188:drug therapy / Q000209:etiology; D055815:Young Adult
chemical_list: D014807:Vitamin D; D002762:Cholecalciferol