EVIDENCE FOR BOTH GENERALIZED AND REGIONAL LOW BONE MASS AMONG ELDERLY WOMEN

The consistency of bone mass measurements across bone sites was examin ed in a cohort of elderly Japanese-American women. The study included 744 women of mean age 66.6 years (age range 47-82 years) who had bone densitometry measurements at the spine, calcaneus, and distal and prox imal radius. The women were classified at the four bone sites as in th e lower, middle, or upper bone mass tertile for their age. Slightly mo re than half (56%) of the women were in the lower tertile at one or mo re of the bone sites, and such women were usually in the lower categor y at more than one site. Of the women, 24% were classified in the lowe r tertile at all four sites. Furthermore, as a group, women classified as in the low bone mass category at any one site had a low average bo ne mass at all four sites. Prospectively, the number of low bone mass sites predicted the risk of new spine fractures after adjusting for ag e and the number of spine and nonspine prevalent fractures. The risk i ncreased approximately 1.3-fold for each additional low bone mass site . A subgroup (15%) of the population had marked heterogeneity in bone mass between sites. These women had one or more lower tertile bone mas s site(s) and one or more upper tertile bone mass site(s). The results suggest that osteoporosis may occur as either a generalized or as a r egional disorder.