Bone Abstracts

Objectives: Studies indicate that later puberty is associated with lower bone mineral density (BMD) in childhood. Less is known about effects of puberty timing on long-term bone accrual. We examined association between age at puberty and BMD accrual rate from 10 to 25 years.

Methods: This was a prospective birth cohort of healthy largely European people born in southwest England in 1991–1992 and regularly follow-up from birth to mean age 25 years. Age at puberty was measured by age at peak height velocity (APHV), which was estimated using Super Imposition by Translation and Rotation growth curve modelling of >110,000 repeated height measurements. Whole-body BMD (g/cm²) was derived from dual-energy x-ray absorptiometry scans at ages 10, 12, 14, 16, 18 and 25 and these repeat measures were used to model BMD accrual. Association between APHV and BMD accrual rate was examined using linear spline models containing interaction terms between APHV and age splines. Models were adjusted for maternal education, birth weight and body mass index at age 7.

Results: We included 6613 participants (50% female) with ~27,000 bone scans. Mean APHV was 13.5 years (standard deviation=0.9) in males and 11.6 years (standard deviation=0.8) in females. BMD increased over follow-up, with fastest accrual between 1-year pre-APHV to 2-years post-APHV (males=0.139 g/cm²/year (95% confidence interval: 0.127 to 0.151), females=0.106 g/cm²/year (0.098 to 0.114)). Per year older APHV was associated with faster but decelerating BMD accrual; the fastest rate was between 14–16 years (males=0.013 g/cm²/year (0.011 to 0.015), females=0.014 g/cm²/year (0.014 to 0.015)) and the slowest rate between 18–25 years (males=0.002 g/cm2/year (0.001 to 0.003), females=0.000 g/cm²/year (−0.001 to 0.000). Per year older APHV was associated with consistently lower BMD, e.g. at age 14: males=−0.050 g/cm² (−0.055 to −0.045), females=−0.044 g/cm² (−0.046 to −0.041), and at age 25: males=−0.048 g/cm² (−0.052 to −0.044), females=−0.035 g/cm² (−0.037 to −0.032). Findings were similar for site specific (including hip) BMD accrual.

Conclusion: Later puberty is associated with persisting lower BMD up to age 25, despite some temporary catch up in BMD accrual during puberty. Advice on how to maximise BMD and minimise its decrease in later life might be particularly important for those with older pubertal age.

Disclosure: The authors declared no competing interests.