title: Two-year changes in bone density after Roux-en-Y gastric bypass surgery.
abstract: BACKGROUND
  Bariatric surgery is increasingly popular but may lead to metabolic bone disease.
  
  
  OBJECTIVE
  The objective was to determine the rate of bone loss in the 24 months after Roux-en-Y gastric bypass.
  
  
  METHODS
  This was a prospective cohort study conducted at an academic medical center.
  
  
  METHODS
  The participants were adults with severe obesity, including 30 adults undergoing gastric bypass and 20 nonsurgical controls.
  
  
  RESULTS
  We measured bone mineral density (BMD) at the lumbar spine and proximal femur by quantitative computed tomography (QCT) and dual-energy x-ray absorptiometry at 0, 12, and 24 months. BMD and bone microarchitecture were also assessed by high-resolution peripheral QCT, and estimated bone strength was calculated using microfinite element analysis.
  
  
  RESULTS
  Weight loss plateaued 6 months after gastric bypass but remained greater than controls at 24 months (-37 ± 3 vs -5 ± 3 kg [ mean ± SEM]; P < .001). At 24 months, BMD was 5-7% lower at the spine and 6-10% lower at the hip in subjects who underwent gastric bypass compared with nonsurgical controls, as assessed by QCT and dual-energy x-ray absorptiometry (P < .001 for all). Despite significant bone loss, average T-scores remained in the normal range 24 months after gastric bypass. Cortical and trabecular BMD and microarchitecture at the distal radius and tibia deteriorated in the gastric bypass group throughout the 24 months, such that estimated bone strength was 9% lower than controls. The decline in BMD persisted beyond the first year, with rates of bone loss exceeding controls throughout the second year at all skeletal sites. Mean serum calcium, 25(OH)-vitamin D, and PTH were maintained within the normal range in both groups.
  
  
  CONCLUSIONS
  Substantial bone loss occurs throughout the 24 months after gastric bypass despite weight stability in the second year. Although the benefits of gastric bypass surgery are well established, the potential for adverse effects on skeletal integrity remains an important concern.
authors: Endocrine Unit (E.W.Y., M.L.B., M.S.P., E.L.M., A.E.R., J.S.F.), and Weight Center (J.S.A.P., W.S.B.), Massachusetts General Hospital, Boston, Massachusetts 02114.
authors: Elaine W
authors: EW
authors: Yu
authors: Mary L
authors: ML
authors: Bouxsein
authors: Melissa S
authors: MS
authors: Putman
authors: Elizabeth L
authors: EL
authors: Monis
authors: Adam E
authors: AE
authors: Roy
authors: Janey S A
authors: JS
authors: Pratt
authors: W Scott
authors: WS
authors: Butsch
authors: Joel S
authors: JS
authors: Finkelstein
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000453:epidemiology / Q000209:etiology; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass / Q000009:adverse effects; D006615:Hip / Q000000981:diagnostic imaging; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000601:surgery*; D011884:Radius / Q000000981:diagnostic imaging; D013977:Tibia / Q000000981:diagnostic imaging; D015431:Weight Loss / Q000502:physiology
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