Bone growth patterns in Chinese children and adolescents: A 6-year follow-up study provides evidence for sexual dimorphism and tracking

Summary: We prospectively examined bone growth patterns in 894 children aged 6-17 years at the baseline visit, with a 6-year follow-up. Results show bone "tracking" over a six-year interval and sexual dimorphism of bone attained levels and timing of peak bone growth. Our findings underscore childhood and adolescence as critical periods for building bone and developing gender differences. Introduction: Bone growth patterns were prospectively examined in 894 Chinese children (496 males), aged 6-17 yrs, from a population-based twin cohort. Whole-body bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) were measured by DEXA at baseline and a 6-yr follow-up. Methods: Graphic smoothing plots and generalized estimating equations were used to model bone attained levels, growth, and "tracking". Results: Attained levels of BMC and BA increased curvilinearly with age. Male attained levels were higher than females after age ∼15 yr, but BMD was lower between 13-17 yrs (Tanner stage I to IV). In both genders, peak BMC and BMD growth lagged ∼2 yrs behind peak BA growth, which lagged 2 yrs behind peak height growth. Peak bone growth occurred 1-3 yrs later in males. Over the 6-yr follow-up, all bone measurements "tracked", but "shifting" across ranks also occurred, and baseline tertile ranking influenced bone growth. Females with early menarche had higher attained levels than females with late menarche at age 12-13 yrs. Conclusion: Our findings confirm and expand previous studies on peak bone growth conducted in Caucasian cohorts, particularly sexually dimorphic and maturational effects. The significant "tracking" of bone measurements in this 6-yr follow-up study underscores the importance that osteoporosis prevention should begin in childhood and adolescence.