Abnormal Bone Turnover Observed in Obese Children based on Puberty Stage-Specific Bone Turnover Marker Reference

Context Childhood and adolescence are critical periods for lifelong bone health. The impact of obesity on these phases is controversial, which may be due to the lack of standards for age-, sex-, and puberty-specific bone turnover markers (BTMs) that could sensitively reflect bone metabolism. Objective To generate age-, sex, and puberty stage-specific BTM reference curves in children and adolescents and to explore the effect of obesity on bone metabolism in the Chinese population. Methods Our study was part of the Evaluation and Monitoring on School-based Nutrition and Growth in Shenzhen study. A total of 800 participants aged 6 similar to 18 years with normal body mass index (BMI) were selected to establish BTM reference curves for boys and girls at different ages under different pubertal development stages. Additionally, 200 participants with obesity (BMI > 95th percentile) were matched with healthy children from the original cohort at a 1:1 ratio. All participants underwent bone mineral density assessment, and serum levels of procollagen type 1 N-propeptide (P1NP) and beta-C-telopeptide of type I collagen (CTX) were measured. Results The BTM values presented significant age, sex, and puberty stage differences. Analysis of serum BTMs based on the established reference revealed a higher percentage of low-level P1NP in boys with obesity (P = .005); no significant difference was observed in girls. However, the obese group showed a significantly higher proportion of high beta-CTX levels for girls, not boys (P = .022). Conclusion We provide age-, sex-, and puberty stage-specific P1NP and beta-CTX reference curves. According to these, obesity appeared to be a negative factor for bone formation in boys and for bone resorption in girls.