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 laparo-scopic 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 sta-tus. 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/m2; P < 0.001). Markers of bone turnover were significantly elevated in pa-tients post LRGB compared with controls (urinary N-telopep-tide 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 mas