Bone Composition Changes and Calcium Metabolism in Obese Adolescents and Young Adults Undergoing Sleeve Gastrectomy: A Systematic Review

Background/Objectives: Sleeve gastrectomy (SG) is increasingly used to treat severe obesity in adolescents, but its effects on bone health during this critical period of bone accrual are not fully understood. This systematic review aims to evaluate the impact of SG on the bone mineral density (BMD), bone microarchitecture, marrow adipose tissue (MAT), and bone turnover markers in adolescents. Methods: A comprehensive literature search was conducted to identify studies assessing bone health outcomes in adolescents undergoing SG. Nine studies met the inclusion criteria, comprising prospective cohorts, observational cohorts, and one randomized controlled trial, with sample sizes ranging from 10 to 197 participants aged 13 to 25 years, and a total sample size of 597 individuals. Data were extracted and synthesized into tables summarizing changes in BMD, bone microarchitecture, MAT, and bone turnover markers. Results: SG in adolescents is associated with significant reductions in areal BMD at critical skeletal sites, particularly the femoral neck and total hip, with decreases ranging from −4.7% to −8.9%. Studies utilizing high-resolution peripheral quantitative computed tomography (HRpQCT) reported deteriorations in bone microarchitecture, including a decreased trabecular number, increased trabecular separation, and reduced cortical thickness. Two studies observed significant increases in MAT at the lumbar spine post-SG. Elevated bone turnover markers, particularly C-terminal cross-linking telopeptide (CTX), indicate increased bone resorption following SG. Conclusions: SG leads to negative effects on bone health in adolescents, including reductions in BMD, deterioration of the bone microarchitecture, increases in MAT, and elevated bone resorption markers. These findings highlight the need for careful monitoring of bone health and the development of strategies to mitigate bone loss in adolescents undergoing SG.