Different trends of age-related diminution of bone mineral content in the lumbar spine, femoral neck, and femoral shaft in women.

The bone mineral content (BMC) was measured by dual photon absorptiometry of 153Gd simultaneously in the lumbar spine, femoral neck, and femoral shaft in a cross-sectional study of 113 healthy women aged 20-89 years. The measurements suggest differences in the patterns of bone mineral decrease at the three sites of the skeleton in relation to age. The lumbar spine BMC decreases mainly during the usual time of menopause, whereas BMC decreases linearly in the femoral neck from young adulthood to old age. The femoral shaft BMC is nearly unaltered until the seventh decade, and thereafter BMC declines significantly. In each of the three age groups selected according to the usual time for menopause there was significant correlations between BMC of the scanning sites and nearly identical variance of BMC with age, suggesting homogeneity in the female population with regard to rate of bone diminution.