Bone density in white Brazilian women: rapid loss at the time around the menopause

Dual energy x-ray absorptiometry (DXA) was used to measure bone mineral density (BMD) of the lumbar spine and proximal femur (neck, Ward's triangle, and trochanter) in 417 normal women (aged 20-79) living in São Paulo, Brazil. Bone density decreased with age at all sites. At the spine, the greatest decrease occurred during the sixth decade, with an average 11.4% bone loss compared with the previous decade. Stratifying the subjects according to menopausal status revealed that the fastest bone loss occurred at the time around the menopause (ages 45-60) when the rate of bone loss (-0.66%/year) was almost twice as rapid as in postmenopausal women (-0.39%/year). Although significant linear rates of bone loss were detected in all proximal femur sites before the menopause, a menopause-dependent pattern was less evident than at the spine. Lifetime rates of bone loss at the appendicular skeleton were -0.43, -0.62, and -0.35%/year at the femoral neck, Ward's triangle, and trochanteric area, respectively. After the menopause, BMD declined with menopausal age at all sites, although the rate of bone loss was faster at the femoral neck (-0.62%/year) and Ward's triangle (-0.84%/year) than at the spine (-0.49%/year). The results are consistent with the notion that in women, the fastest bone loss occurs at the time around the menopause, most likely consequent to ovarian failure; and that faster rates of bone loss are detected at the proximal femur than at the lumbar spine in late postmenopausal women.