Long-Term Effects of Roux-en-Y Gastric Bypass and Sleeve Gastrectomy on Bone Mineral Density: a 4-Year Longitudinal Study

Abstract

Bone mineral density (BMD) declines in the initial years after bariatric surgery, but long-term skeletal effects are unclear and comparisons between sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) are rare. An observational longitudinal study of obese patients undergoing SG or RYGB was performed. Whole-body (WB) BMD, along with BMD of the total hip (TH), femoral neck (FN), and lumbar spine (LS), was measured by dual-energy X-ray absorptiometry (DXA) before surgery and yearly thereafter for 4years. Calciotropic hormones were also measured. Forty-seven patients undergoing RYGB surgery and 28 patients undergoing SG were included. Four years after RYGB, BMD declined by 2.8 ± 5.8% in LS, 8.6 ± 5% in FN, 10.9 ± 6.3% in TH, and 4.2 ± 6.2% in WB, relative to baseline. For SG, BMD declined by 8.1 ± 5.5% in FN, 7.7 ± 6% in TH, 2.0 ± 7.2% in LS, and 2.5 ± 6.4% in WB after 4years, relative to baseline. Vitamin D levels increased with supplementation in both groups. Whereas parathyroid hormone levels increased slightly in the RYGB group, they decreased modestly in the SG group (P< 0.05 in both groups). Bone loss after 4years was comparable between the two procedures, although RYGB was associated with a slightly greater decrease at the TH than SG. Bone health should therefore be monitored after both RYGB and SG.