Age-related distribution of bone and skeletal parameters in 1,322 Japanese young women.

We explored factors that could serve as indices for therapeutic intervention aimed at prevention of osteoporosis. In this cross-sectional study, we investigated the timing of peak bone mass (PBM) in 1,322 Japanese women aged 12-30 years old. We measured height, body weight, bone mineral density (BMD), bone mineral content (BMC), and bone area at the lumbar spine and total hip, as well as the blood markers calcium, phosphorus, and the bone metabolic markers bone alkaline phosphatase (BAP) and type I collagen cross-linked N-telopeptide (NTX). All measurements were standardized with the mean at age 18 defined as 100% to identify age-related differences. In the total hip, BMD peaked at age 18, while, in the lumbar spine, BMD peaked at age 29, of which 99.8% was attained at age 18, suggesting that peak BMD was attained at age 18 at both the total hip and lumbar spine. No age difference was observed in serum calcium, while there was a 15.1% decrease between ages 12 and 18 in serum phosphorus. There were 273.8% and 208.5% decreases in serum BAP and NTX, respectively, between ages 12 and 18, while these levels remained constant thereafter, suggesting that bone and calcium metabolism are constant between ages 19 and 30. Factors that had stronger correlations with BMD, BMC, and bone area from 12 years to 18 years were height and body weight. PBM was reached at age 18. Control of body weight by using total hip BMD as an index for intervention should be reasonable.