Roux-en-Y Gastric Bypass Surgery Associated With Long-Term Bone Loss

Five years after undergoing Roux-en-Y gastric bypass, areal and volumetric bone density and skeletal microarchitecture continued to deteriorate, leading to substantial cumulative bone loss in patients, according to study findings published in the Journal of Clinical Endocrinology & Metabolism.

Roux-en-Y gastric bypass is a common type of weight loss surgery that has been associated with negative skeletal effects, especially in the first few years after the procedure. To assess whether these skeletal changes progress, researchers evaluated bone density and bone microarchitecture 5 years after surgery in a cohort of 21 severely obese adults (mean age, 51 years) who underwent Roux-en-Y gastric bypass at an academic medical center. The investigators also assessed whether changes in weight, body composition, and calciotropic or entero-osseous hormones were associated with bone loss.

Longitudinal data indicated that at 5 years, areal bone mineral density declined by -7.8±7.6% at the spine and −15.3±6.3% at the total hip (P ≤.001). However, the rate of bone loss did appear to slow down after the initial years following Roux-en-Y gastric bypass. In a similar fashion, trabecular spine volumetric bone mass density decreased by −12.1±12.3% by 5 years post-surgery (P ≤.001). Volumetric bone mass density also continued to decline at a steady rate at peripheral sites. In addition, bone turnover markers showed a dramatic increase following Roux-en-Y gastric bypass. By 2 years, serum I collagen C-terminal telopeptide was 196±143% higher than at baseline and remained 150±146% above baseline at 5 years (P <.001).

Baseline age and weight did not predict bone density loss and there were no statistically significant associations between sex and menopause status and skeletal changes. The investigators did, however, find an association between lean mass loss and declines in spine and hip bone density.

Underlying mechanisms of bone loss as a result of Roux-en-Y gastric bypass remain unclear, although they are likely multifactorial. “Adults undergoing [Roux-en-Y gastric bypass] surgery warrant close follow-up to detect changes in bone density as well as to prevent secondary hyperparathyroidism and promote physical activity,” concluded the investigators.

Reference

Lindeman KG, Greenblatt LB, Rourke C, Bouxsein ML, Finkelstein JS, Yu EW. Longitudinal 5-year evaluation of bone density and microarchitecture after Roux-en-Y gastric bypass surgery [published online September 13, 2018]. J Clin Endocrinol Metab. doi:10.1210/jc.2018-01496