Comparison of cross-sectional and longitudinal measurements of age-related changes in bone mineral content.

Age-related, postmenopausal bone loss was examined among a cohort of Japanese-American women living in Hawaii. None of the women were using estrogens or thiazides. Cross-sectional and longitudinal measurements of bone mineral content were compared at the calcaneus, the proximal radius, and the distal radius. Cross-sectional measurements were also available for the lumbar spine. The longitudinal data showed a slowing rate of bone loss with increasing age at the radius sites. By contrast, the cross-sectional data suggested constant rates of bone loss for all ages at both radius sites and the spine. The calcaneus demonstrated a complex pattern of bone loss in both cross-sectional and longitudinal analyses. The loss rates among women in their fifties were greater than for those in their sixties. From the middle sixties onward calcaneal bone loss remained essentially constant. Because of the sustained bone loss, however, women in their seventies were actually losing greater percentages of their calcaneal bone mineral than they had in their sixties.