Effects of laparoscopic Roux-en-Y gastric bypass on bone mineral density and markers of bone turnover

Kosisochi M. Obinwanne, Kevin P. Riess, Kara J. Kallies, Michelle A. Mathiason, Brian R. Manske

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Background Despite multiple beneficial effects of weight loss after laparoscopic Roux-en-Y gastric bypass (LRYGB), the influence on bone mineral density (BMD) remains largely unknown. Our objective was to evaluate the changes in BMD and serum/urine bone markers after LRYGB.

Methods Thirty-four women undergoing LRYGB were prospectively enrolled and underwent bone densitometry and serum/urine analysis preoperatively and 1 year postoperative. Changes ≥.025 g/cm2 in hip, femoral neck, and spine BMD and decreases>2% in total BMD were considered significant. Statistical analysis included paired t tests and McNemar's test.

Results Mean age was 44.6 years. Body mass index at the preoperative and 1-year postoperative intervals were 46.7 and 29.6 kg/m2, respectively. Mean hip, femoral neck, and spine (L1-L4) BMD was 1.191 versus 1.087 g/cm2 (P<.001), 1.105 versus 1.032 g/cm2 (P<.001), and 1.323 versus 1.277 g/cm2 (P<.001) at the preoperative and 1 year postoperative intervals, respectively. Mean total BMD decreased from 1.328 preoperatively to 1.251 g/cm2 at 1 year postoperative (P<.001). The decreases in BMD were 5.8%, 6.5%, 3.5%, and 8.8% for hip, femoral neck, spine (L1-L4) and total BMD from preoperative to 1 year postoperative. The proportion of patients with low vitamin D levels decreased from 55% preoperatively to 21% at 1 year postoperative (P =.004). Elevated osteocalcin and bone alkaline phosphatase was observed in 4% and 63% (P<.001), and 14% and 41% (P =.011) of patients preoperatively and at 1 year postoperative, respectively.

Conclusion BMD and bone markers changed significantly after LRYGB. Current recommendations for supplementation in post-LRYGB women may need to be reevaluated.

Original languageEnglish (US)
Pages (from-to)1056-1062
Number of pages7
JournalSurgery for Obesity and Related Diseases
Issue number6
StatePublished - Nov 1 2014

Bibliographical note

Funding Information:
The authors gratefully acknowledge funding for this study provided by the Gundersen Medical Foundation and grant support provided by the Foundation for Surgical Fellowships for the Minimally Invasive Bariatric Surgery and Advanced Laparoscopy Fellowship.

Publisher Copyright:
© 2014 American Society for Metabolic and Bariatric Surgery. All rights reserved.


  • Bone density
  • Bone resorption
  • Calcium
  • Gastric bypass
  • Osteocalcin
  • Vitamin D


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