The aim of this study aas to investigate the effect of menopause on bo
ne loss in the proximal femur and the lumbar spine. The rates of chang
e in bone mineral density (BMD) were measured longitudinally by dual X
-ray absorptiometry (DXA) at the femoral neck (FN), Ward's triangle (W
T), and trochanter (TR) together with the lumbar spine in 81 healthy p
ostmenopausal women (45-65 years of age) who had passed a natural meno
pause, 6 months to 12 years before, A significant correlation between
the rate of change and interval since menopause was evidenced. The bes
t fit of the data was a binomial function of interval since menopause
at the spine, FN, and WT and a simple linear regression at TR level, A
t each skeletal site, the rate of bone loss (mean +/- SD) was signific
antly different (p < 0.05) and twice as high in women who were between
6 months and 2 years postmenopausal at enrollment (FN, -1.82 +/- 1.1%
; WT, -2.43 +/- 1.7%; TR, -1.12 +/- 1.7%) than in those who were beyon
d 5 years of menopause (FN, -0.48 +/- 0.8%; WT, -0.68 +/- 2.1%; TR, 0.
41 +/- 1.2%). A poor correlation (r = 0.39 - 0.42, p < 0.001),vas foun
d between the rate of vertebral and that of femoral postmenopausal bon
e loss, This study demonstrates that menopause is associated with a ra
pid and transient bone loss in BMD of the proximal femur, which declin
es with time after 3 years, These data suggest that therapy should be
initiated as early as possible after menopause to prevent bone toss.