Age-related bone loss: Relationship between age and regional bone mineral density

We assessed the changes in regional bone mineral density according to age a nd examined the relationship between various regional bone mineral densitie s. The study was conducted in 985 Japanese women divided into < 50-years gr oup (n = 435) and greater than or equal to 50 years group (n=550). The tota l body bone mineral density and that of the head, arm, leg, thoracic (T)-sp ine, lumbar (L)-spine, ribs, and pelvis were measured using dual energy x-r ay absorptiometry. There was a significant generalized reduction of bone mi neral density in all regions after the age of 50 years. The most marked age -related decrease was observed in the L-spine. Bone mineral densities in al l regions significantly correlated to each other in both age groups, but th e degree of significance varied among regions. The relationship between bon e mineral density of the L-spine and that of T-spine regions was the most s ignificant in both groups. In the <50-years group, the correlation between bone mineral density of the pelvis and that of L-spine and T-spine was the highest, followed by that between the pelvis and the leg. On the ether hand , in the greater than or equal to 50-years group, the correlation between b one mineral density of the pelvis and that of the leg was the highest, but not the L-spine of T-spine. Since spine measurements are affected by verteb ral deformity and/or aortic calcification, our findings suggest the pelvis may be a useful region for screening measurements of bone mineral density, especially in older women.