AGE OF MENARCHE AND AGE OF PEAK BONE MINERAL ACQUISITION IN ADOLESCENT GIRLS396

Abstract

To explore the possibility of optimizing bone mineral accrual in the growing skeleton, it is first necessary to have an understanding of normal hormonal influences on patterns of growth and bone mineral acquisition. To investigate this, we studied the relationship between the age of peak height velocity (PHV) and the age of peak bone mineral content velocity (PBMCV) with the age of menarche in 42 girls. Subjects were healthy adolescents who were part of an on-going longitudinal study of bone mineral acquisition which is now in its sixth year. The ages of PHV and PBMCV were determined by calculating the rate of change between test occasions, and selecting the age center for the time interval where the highest velocity value for each child occurred. Determinations were based on 12 height and 6 bone mineral measures taken over a six year period. Age of menarche was determined on the basis of an interview administered annually. Results are shown in the followingtable. In 60 percent of the girls (n=25), the interval between the age of PBMCV and the age of menarche was less than 0.5 years and in only 4 girls was the interval greater than 1 year. The correlation between the age of PBMCV and the age of menarche was 0.79. On the basis of these data we conclude that in girls the peak rate of bone mineral acquisition occurs concurrently with the rising estrogen levels that accompany the onset of menstruation. This occurs approximately one (1) year after the age of PHV.