Gastric bypass surgery for morbid obesity leads to an increase in bone turnover and a decrease in bone mass.
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.
Coates
Penelope S
PS
Osteoporosis Prevention and Treatment Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Fernstrom
John D
JD
Fernstrom
Madelyn H
MH
Schauer
Philip R
PR
Greenspan
Susan L
SL
D000328:Adult; D015519:Bone Density; D016723:Bone Remodeling; D001842:Bone and Bones / Q000378:metabolism; D002136:Calcium, Dietary / Q000008:administration & dosage; D005260:Female; D015390:Gastric Bypass / Q000009:adverse effects*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*; D011446:Prospective Studies; D014807:Vitamin D / Q000008:administration & dosage; D015431:Weight Loss
D002136:Calcium, Dietary; D014807:Vitamin D