Gastric bypass surgery for morbid obesity leads to an increase in bone turnover and a decrease in bone mass

J Clin Endocrinol Metab. 2004 Mar;89(3):1061-5. doi: 10.1210/jc.2003-031756.

Abstract

Little is known about the effects on the skeleton of laparoscopic Roux-en-Y gastric bypass (LRGB) surgery for morbid obesity and subsequent weight loss. We compared 25 patients who had undergone LRGB 11 +/- 3 months previously with 30 obese controls matched for age, gender, and menopausal status. Compared with obese controls, patients post LRGB had significantly lower weight (92 +/- 16 vs. 133 +/- 20 kg; P < 0.001) and body mass index (31 +/- 5 vs. 48 +/- 7 kg/m(2); P < 0.001). Markers of bone turnover were significantly elevated in patients post LRGB compared with controls (urinary N-telopeptide cross-linked collagen type 1, 93 +/- 38 vs. 24 +/- 11 nmol bone collagen equivalents per mmol creatinine; and osteocalcin, 11.6 +/- 3.4 vs. 7.6 +/- 3.6 ng/ml; both P < 0.001). Fifteen patients were studied prospectively for an average of 9 months after LRGB. They lost 37 +/- 9 kg and had a 29 +/- 8% fall in body mass index (both P < 0.001). Urinary N-telopeptide cross-linked collagen type 1 increased by 174 +/- 168% at 3 months (P < 0.01) and 319 +/- 187% at 9 months (P < 0.01). Bone mineral density decreased significantly at the total hip (7.8 +/- 4.8%; P < 0.001), trochanter (9.3 +/- 5.7%; P < 0.001), and total body (1.6 +/- 2.0%; P < 0.05), with significant decreases in bone mineral content at these sites. In summary, within 3 to 9 months after LRGB, morbidly obese patients have an increase in bone resorption associated with a decrease in bone mass. Additional studies are needed to examine these findings over the longer term.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Bone Density*
  • Bone Remodeling*
  • Bone and Bones / metabolism
  • Calcium, Dietary / administration & dosage
  • Female
  • Gastric Bypass / adverse effects*
  • Humans
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Obesity, Morbid / surgery*
  • Prospective Studies
  • Vitamin D / administration & dosage
  • Weight Loss

Substances

  • Calcium, Dietary
  • Vitamin D