Gains in height substantially outpaced gains in skeletal site-specific bone mineral content (BMC) in a diverse group of healthy children, researchers report. Data were published in JAMA Pediatrics.
Such outpacing of gains in height compared with whole body BMC during childhood could contribute to increased risk for fracture in childhood. That a significant percentage of bone accrued only after adult height was achieved also suggests that late adolescence still provides an opportunity to optimize bone mass.
The researchers assessed healthy children, adolescents, and young adults age 5 to 19 at the start of the study. The participants were evaluated annually for up to 7 years.
Subjects included 2014 healthy children, adolescents, and young adults (50.7% female; 23.8% African American). The mean age of peak height velocity was 13.1 years in African American boys vs 13.4 years in non-African American boys (difference, –0.3 years; 95% CI, –0.4 to –0.1 years). In African American girls, mean age of peak height velocity was 11 years vs 11.6 years in non-African American girls (difference, –0.6 years; 95% CI, –0.7 to 0.5 years).
The age of peak acquisition of whole body BMC was 14 years in both African American and non-African American boys; in girls, peak acquisition of whole body BMC was 12.1 and 12.4 years in African American and non-African American girls, respectively.
At age 7, children had acquired most of their maximal observed height — 69.5% to 74.5% — but only 29.6% to 38.1% of their maximal observed whole body BMC. Non-African American boys were at greatest risk for fracture, which peaked approximately 1 year before peak height velocity.
All adolescents gained approximately one-third of their maximal observed whole body BMC during the 2 years before and the 2 years after peak height velocity.
“A significant proportion of bone is accrued after adult height is achieved,” the researchers concluded. “Therefore, late adolescence represents a potentially underrecognized window of opportunity to optimize bone mass.”
McCormack SE, Cousminer DL, Chesi A, et al. Association between linear growth and bone accrual in a diverse cohort of children and adolescents [published online July 3, 2017]. JAMA Pediatr. doi:10.1001/jamapediatrics.2017.1769