Effect of Bariatric Surgery on Bone Mineral Density: Comparison of Gastric Bypass and Sleeve Gastrectomy

The aim of our study was to compare bone mineral density (BMD) a year after Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) in age- and body mass index-matched women. In 33 morbidly obese women undergoing RYGB and 33 undergoing SG, plasma determinations of calcium, parathyroid hormone (PTH), 25-hydroxyvitamin D (25(OH) D₃), and insulin-like growth factor-I (IGF-I) were made prior to and at 12 months after surgery. Dual-energy X-ray absorptiometry was performed in all patients 1 year after surgery. BMD at the femoral neck and the lumbar spine 1 year after surgery was similar in women undergoing RYGB and SG (1.01?±?0.116 vs. 1.01?±?0.122 g/cm², p?=?0.993; 1.05?±?0.116 vs. 1.08?±?0.123 g/cm², p?=?0.384). The percentage of patients with osteopenia and osteoporosis was not different between groups. In the linear regression analysis, age (β?=??0.628, p?=?0.034) and lean mass 12 months after surgery (β?=?0.424, p?=?0.021) were found to be the main determinants of femoral neck BMD. Age (β?=??0.765, p?=?0.025), menopause (β?=??0.898, p?=?0.033), and lean mass (β?=?0.615, p?=?0.023) were determinants of BMD at the lumbar spine. No influence was found between low bone mass and type of surgery, plasma PTH, 25(OH) D₃, or IGF-I. The effect of RYGB and SG on BMD was comparable a year after surgery. Menopausal women were at a higher risk of having low bone mass, but the presence of osteoporosis was uncommon.