title: Secondary hyperparathyroidism, vitamin D sufficiency, and serum calcium 5 years after gastric bypass and duodenal switch.
abstract: BACKGROUND
  The prevalence of secondary hyperparathyroidism (SHPT) is high after bariatric surgery. Vitamin D is supplied to counteract SHPT and bone disease, and we studied vitamin D associations with SHPT.
  
  
  METHODS
  We measured serum levels of 25-OH vitamin D and parathyroid hormone (PTH) 5 years after gastric bypass and duodenal switch. One hundred twenty-five patients were included, of whom 114 (91 %) had undergone gastric bypass and 11 (9 %) had undergone duodenal switch. SHPT was defined as PTH > 7.0 pmol/l in the absence of hypercalcemia. 25-OH vitamin D levels were divided into three categories: <50, 50-74, and ≥75 nmol/l. Serum ionized calcium, magnesium, phosphate, and creatinine were divided into tertiles.
  
  
  RESULTS
  Mean age ± SD was 44 ± 9 years at 5 years follow-up. Ninety out of 125 (72 %) patients were women. SHPT was present in 45 out of 114 (40 %) gastric bypass patients and in 11 out of 11 (100 %) duodenal switch patients. The prevalence was high in all vitamin D categories studied. An inverse association between ionized calcium and PTH was found. For the gastric bypass patients, the odds ratio for SHPT in the upper two tertiles of ionized calcium was 0.35; 95 % CI, 0.15-0.79; p = 0.011, compared with the lowest tertile. Supplements of vitamin D and calcium were not associated with a lower prevalence of SHPT at 5 years follow-up.
  
  
  CONCLUSIONS
  The prevalence of SHPT was high 5 years after gastric bypass and duodenal switch. SHPT was inversely associated with serum ionized calcium, but not with vitamin D. The supplementation used was insufficient to compensate for the impaired calcium absorption after surgery.
authors.affiliation: Department of Morbid Obesity and Bariatric Surgery, Department of Medicine, Oslo University Hospital Aker, P.O. Box 4959, Nydalen, 0424, Oslo, Norway. stehewi@online.no
authors.forename: Stephen
authors.initials: S
authors.lastname: Hewitt
authors.forename: Torgeir T
authors.initials: TT
authors.lastname: Søvik
authors.forename: Erlend T
authors.initials: ET
authors.lastname: Aasheim
authors.forename: Jon
authors.initials: J
authors.lastname: Kristinsson
authors.forename: Jørgen
authors.initials: J
authors.lastname: Jahnsen
authors.forename: Grethe S
authors.initials: GS
authors.lastname: Birketvedt
authors.forename: Thomas
authors.initials: T
authors.lastname: Bøhmer
authors.forename: Erik F
authors.initials: EF
authors.lastname: Eriksen
authors.forename: Tom
authors.initials: T
authors.lastname: Mala
mesh_terms: D000328:Adult; D002118:Calcium / Q000097:blood*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004386:Duodenum / Q000601:surgery*; D005260:Female; D015391:Gastroplasty / Q000379:methods*; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D009767:Obesity, Morbid / Q000097:blood* / Q000453:epidemiology; D011183:Postoperative Complications; D011184:Postoperative Period; D015995:Prevalence; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014807:Vitamin D / Q000097:blood*
chemical_list: D014807:Vitamin D; D002118:Calcium