PP174 - EVOLUTION OF BONE MINERAL DENSITY ONE YEAR AFTER ROUX-EN-Y GASTRIC BYPASS

PP174

EVOLUTION OF BONE MINERAL DENSITY ONE YEAR AFTER ROUX-EN-Y GASTRIC BYPASS

M. S. Plenc Ziegler^1,*, D. Ramakrishnan², Y. M. Dupertuis², J. P. Willi³, L. Wilmart², E. Biver⁴, M. Jung⁵, L. Genton²

¹Clinical Nutrition Unit, 1Geneva University Hospitals, ²Clinical Nutrition Unit, ³Nuclear Medicine, ⁴Bone Diseases Department, ⁵Division of Visceral Surgery, Department of Surgery, Geneva University Hospitals, Geneva, Switzerland

Rationale: Roux-en-Y Gastric bypass surgery (RYGB) induces major weight loss (WL) and resolution of obesity related metabolic comorbidities but is associated with alterations in bone metabolism. We aimed to assess changes in bone mineral density (BMD) after the first postoperative year and to identify associated clinical factors. 

Methods: Observational longitudinal study, including adults undergoing RYGB at Geneva University Hospitals between 2022 and 2024. Anthropometric measurements and Dual-energy X-ray absorptiometry were performed preoperatively and 12 months after RYGB to assess lumbar spine and hip BMD, T-scores, whole-body lean and fat mass. Paired comparisons, correlation analyses and multivariable regression adjusted for age, sex, % of WL and lean body mass loss were used to assess BMD changes and associated factors.

Results: Sixty-three patients (67% women) were included, with a mean age of 42,4±10,7 years, mean BMI 42,6±4,8 kg/m². At 12 months, the total body WL (TWL) was 33,5±7,8%. Lumbar spine and hip BMD significantly decreased compared with baseline (-3,8±5,4%; −9,2±4,8% respectively; both p<0.001). Lumbar spine and hip T-scores also significantly decreased after one year (both p<0.001). The prevalence of osteopenia increased from 14,3% to 23,8% and osteoporosis from 1,6% to 4,8%. Absolute Hip BMD loss (g/cm2), but not spine BMD loss, was significantly correlated with %TWL (r = −0.53, p<0.01) and lean body mass reduction (r = 0.39, p = 0.002). In multivariable linear regression analysis, only %TWL remained independently associated with absolute hip BMD loss (β-0,5; 95%CI -00,5 to -0,02; p<0,001).

Conclusion: Significant BMD loss occurred after the first year after RYGB and was associated with the magnitude of TWL. These findings enhance the importance of systematic bone monitoring and implementation of preventive and therapeutic strategies following bariatric surgery. Long-term assessment BMD after RYGB is needed.

Disclosure of Interest: None declared