Peak bone mass inversely associated with age at puberty
MedWire News: Bone mass and density at the time of skeletal maturity are inversely related to the timing of puberty in healthy adolescents, data from the Bone Mineral Density in Childhood Study shows.
"Peak bone mass (PBM) is a major determinant of the future risk for fractures in the elderly and is largely achieved by the end of sexual and skeletal maturity," explain Vicente Gilsanz (Children's Hospital Los Angeles, California, USA) and colleagues.
To determine whether the timing and length of puberty influences bone mineral content (BMC) and bone mineral density (BMD), Gilsanz and team took dual-energy X-ray absorptiometry measurements at the axial and appendicular skeleton among participants of the Bone Mineral Density in Childhood Study before the onset of puberty (Tanner stage II).
Follow-up examinations were taken when participants reached sexual (Tanner stage V) and skeletal maturity, defined as epiphyseal closure of the phalanges and metacarpals, corresponding to bone ages of 16 years for girls and 17 years for boys.
During the course of the study, 78 girls and 85 boys began puberty and reached skeletal maturity a mean of 4.4 and 4.5 years later, respectively. Puberty was defined as breast development between the age of 8 and 13 years for girls, and having a testes size of at least 4 ml between the age of 9 and 14 years for boys.
Multiple linear regression analyses showed that the age of onset of puberty in both boys and girls was a strong negative predictor of BMC and BMD at skeletal maturity, independent of bone values at the beginning of puberty, and the length of puberty.
In girls, each year younger in age at the start of puberty was associated with an approximately 5% greater BMC and 2.5% greater BMD at skeletal maturity, whereas each year older in age at the start of puberty was associated with a respective 5% and 2.5% reduction in BMC and BMD at skeletal maturity. The researchers observed similar findings of a slightly smaller magnitude for age at puberty and skeletal maturity in boys.
Of note, length of puberty was not associated with any of the bone measures examined.
Gilsanz and co-authors conclude in the Journal of Pediatrics that their findings "underscore the need for additional studies to establish whether the potential deficiency in PBM in adolescents with delays in pubertal commencement, even within the normal range, can be prevented as a result of simple nutritional, mechanical, or pharmacologic intervention."
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By Laura Dean