Peak Bone Mineral Density in Young Women-Reply

In Reply. —The comments by Drs Recker and Heaney call to attention our incomplete understanding of the dynamics and probable variation in the peak bone mass concept. From the three recent cross-sectional studies 1-3 of bone density among a total of 197 young women, aged 9 to 21 years, peak lumbar spine and peak femoral neck bone density were observed for between 15 and 18 years. From the two large cross-sectional studies 4,5 using a total of 694 women, aged 20 to 40 years, no peak was observed for lumbar spine or femoral neck bone density after age 20 years. From their longitudinal study of 98 young women aged 9 to 19 years, Theintz and coworkers 6 observed cessation of lumbar spine and femoral neck bone gain by age 18 years. In contrast, Recker and Heaney reported that cessation of total body and spinal bone mineral gain occurred at about age