Sex differences in bone mineral density in 1653 men and women in the sixth through tenth decades of life: the Rancho Bernardo Study.

This cross-sectional population-based study examined the effect of age and sex on bone mineral density (BMD) in the elderly. BMD was measured at the spine and hip using dual-energy x-ray absorptiometry and at midshaft and ultradistal radius using single-photon absorptiometry in 672 men and 981 women aged 50-98 years. In both sexes, mean BMD levels decreased significantly with age at all sites except the male spine. In linear regression models, the slope of loss was significantly greater in women than in men at all sites except the ultradistal radius. The slope was steeper at most sites in women aged 50-59 years than in older women, 60-98 years. In both age groups, mean age-adjusted BMD levels were lower at all sites in women who were past or never users of replacement estrogen than in women who were current estrogen users. Current estrogen users generally had lower slopes of loss with age than never or past estrogen users; however, few of these differences were statistically significant. We conclude that BMD levels decrease in old age in both sexes. Continued bone loss in old age raises the possibility that intervention to retard further loss may still be warranted in the elderly.