Effects of age and menopause on vertebral bone density

Vertebral bone density was assessed with dual photon absorptiometry in 280 white females, aged 19-87, without symptoms of osteoporosis. Those who had not experienced a menstrual period for at least one year were classified as postmenopausal, and those menstruating normally were deemed premenopausal. The remainder were considered perimenopausal. Regression links were fit: (1) to the entire data set, (2) to two groups by age (less than 50, 50+), (3) to three groups by age (less than 40, 40-54, 55+) and (4) to three groups by menopausal status. Only that regression which considered menopausal status had a significantly better fit than the simple linear model with slopes of +0.04% per year for the premenopausal (ns, different from zero), -1.8% per year for the perimenopausal (P less than 0.05) and -0.6% per year for the postmenopausal (P less than 0.05). These data suggest that the loss of trabecular bone is accelerated around the time of the onset of menopause, and slows somewhat thereafter, although continuing to be significant. However, the findings of this study are based on cross-sectional data, and there remains a need for prospective studies of vertebral bone around the time of menopause.