title: Serum vitamin D increases with weight loss in obese subjects 6 months after Roux-en-Y gastric bypass.
abstract: BACKGROUND
  Malabsorptive surgical procedures lead to deficiencies in fat-soluble vitamins. However, results concerning serum vitamin D (25OHD) after gastric bypass (GBP) are controversial. The aim of the study was to assess the influence of GBP on 25OHD and calcium metabolism.
  
  
  METHODS
  Parameters of calcium metabolism were evaluated in 202 obese subjects before and 6 months after GBP. Thirty of them were matched for age, gender, weight, skin color, and season with 30 subjects who underwent sleeve gastrectomy (SG). A multivitamin preparation that provides 200 to 500 IU vitamin D3 per day was systematically prescribed after surgery.
  
  
  RESULTS
  In the 202 patients after GBP, serum 25OHD significantly increased from 13.4 ± 9.1 to 22.8 ± 11.3 ng/ml (p < 0.0001), whereas parathyroid hormone (PTH) did not change. Despite a decrease in calcium intake (p < 0.0001) and urinary calcium/creatinine ratio (p = 0.015), serum calcium increased after GBP (p < 0.0001). Preoperatively, 91 % of patients had 25OHD insufficiency (< 30 ng/ml), 80% deficiency (< 20 ng/ml), and 19% secondary hyperparathyroidism (> 65 pg/ml) vs. 76, 44, and 17%, respectively, following GBP. Serum 25OHD was negatively correlated with BMI at 6 months after GBP (R = -0.299, p < 0.0001). In the two groups of 30 subjects, serum 25OHD and PTH did not differ at 6 months after GBP or SG.
  
  
  CONCLUSIONS
  At 6 months after GBP, serum 25OHD significantly increased in subjects supplemented with multivitamins containing low doses of vitamin D. These data suggest that weight loss at 6 months after surgery has a greater influence on vitamin D status than malabsorption induced by GBP.
authors.affiliation: Service des Explorations Fonctionnelles, Hôpital Louis Mourier (AP-HP), Centre de référence de prise en charge de l'obésité, Université Paris 7 Denis Diderot, 178 rue des Renouillers, 92701, Colombes Cedex, France.muriel.coupaye@lmr.aphp.fr
authors.forename: Muriel
authors.initials: M
authors.lastname: Coupaye
authors.forename: Marie Christine
authors.initials: MC
authors.lastname: Breuil
authors.forename: Pauline
authors.initials: P
authors.lastname: Rivière
authors.forename: Benjamin
authors.initials: B
authors.lastname: Castel
authors.forename: Catherine
authors.initials: C
authors.lastname: Bogard
authors.forename: Thierry
authors.initials: T
authors.lastname: Dupré
authors.forename: Simon
authors.initials: S
authors.lastname: Msika
authors.forename: Séverine
authors.initials: S
authors.lastname: Ledoux
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002118:Calcium / Q000097:blood / Q000378:metabolism* / Q000652:urine; D015331:Cohort Studies; D019587:Dietary Supplements; D005260:Female; D015390:Gastric Bypass / Q000009:adverse effects*; D006801:Humans; D008286:Malabsorption Syndromes / Q000178:diet therapy / Q000209:etiology* / Q000378:metabolism* / Q000601:surgery / Q000652:urine; D008297:Male; D009767:Obesity, Morbid / Q000097:blood / Q000178:diet therapy / Q000378:metabolism* / Q000601:surgery; D010281:Parathyroid Hormone / Q000097:blood; D011446:Prospective Studies; D013997:Time Factors; D014807:Vitamin D / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism* / Q000652:urine; D015431:Weight Loss
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; D002118:Calcium