Bone changes post-sleeve gastrectomy in relation to body mass and hormonal changes.

Objective: To determine mechanisms contributing to impaired bone health in youth 24 months following sleeve gastrectomy (SG).

Design: Twenty-four-month longitudinal observational study.

Methods: Participants included 23 youth undergoing SG and 30 non-surgical controls (NS) 13-25 years old with moderate-to-severe obesity. Subjects underwent fasting labs for bone turnover markers (N-terminal propeptide of type 1 procollagen, C-telopeptide (CTX)), sex hormones, sex hormone binding globulin (SHBG), and enteric peptides, DXA for areal bone mineral density (aBMD) and body composition, high-resolution peripheral quantitative CT for volumetric BMD (vBMD) at the distal radius and tibia, and microfinite element analysis for strength estimates.

Results: Groups did not differ for mean age or BMI z-scores. Over 24 months, compared to NS, SG had greater reductions in BMI z-scores, and spine, hip, and femoral neck aBMD Z-scores (P ≤ .012), greater increases in serum CTX and SHBG (P ≤ .039), and greater decreases in estrone and ghrelin (P ≤ .021). Among females, estrone and free androgen index (FAI) decreased (P ≤ .022) in SG vs NS groups. After controlling for age and sex, decreases in BMI and lean mass were associated with decreases in total hip and femoral neck aBMD Z-scores, and decreases in radial total and trabecular vBMD and failure load, and tibial total and trabecular vBMD. Among females, after controlling for age, decreases in estrone were associated with decreases in spine aBMD Z-scores and radial total and trabecular vBMD, and decrease in FAI with decreases in radial failure load.

Conclusion: Reductions in BMI, lean mass, and sex steroids over 24 months post-SG are associated with bone loss and could be targeted for preventative or therapeutic interventions. Clinical trial registration number: The study is registered in ClinicalTrials.gov (NCT02557438).