Longitudinal 5-Year Evaluation of Bone Density and Microarchitecture After Roux-en-Y Gastric Bypass Surgery

Bone health declines in the initial years after Roux-en-Y gastric bypass (RYGB), but long-term skeletal effects are unclear.

To document longitudinal changes in bone mineral density (BMD) and microarchitecture 5 years after RYGB.

Prospective 5-year observational study of 21 adults with severe obesity receiving RYGB at an academic medical center.

Spine and hip areal BMD were measured by dual-energy X-ray absorptiometry, and trabecular volumetric BMD (vBMD) of the spine was assessed by quantitative CT (QCT). We measured vBMD and microarchitecture of the distal radius and tibia by high-resolution peripheral QCT in a subset of subjects. Serum type I collagen C-terminal telopeptide (CTX) and procollagen type I N-terminal propeptide (P1NP) were also measured.

Areal BMD declined by -7.8% ± 7.6% at the spine and -15.3% ± 6.3% at the total hip by 5 years after RYGB (P ≤ 0.001), although the rate of bone loss slowed in later years. Trabecular spine vBMD decreased by -12.1% ± 12.3% by 5 years (P ≤ 0.001). At peripheral sites, vBMD continued to decrease steadily throughout 5 years, with parallel declines in cortical and trabecular microarchitecture, leading to decreases in estimated failure load of -20% and -13% at the radius and tibia, respectively (P < 0.001). Five years after RYGB, CTX and P1NP were 150% and 34% above baseline (P < 0.001 and P = 0.017, respectively).

Sustained high-turnover bone loss and bone microarchitectural deterioration occur in the 5 years after RYGB. Adults receiving RYGB warrant assessment of bone health.