Changes of regional distribution of bone mineral according to age, gender, and activity.

To assess the pattern of bone mineral distribution over various parts of the skeletal system depending on age, gender, and level of activity, bone mineral content of the head, arms, trunk, and legs was measured and expressed as percentage of the whole-body mineral content (H%, A%, T%, and L%) by a QDR-4,500 (Hologic) in 814 subjects between ages of 20 and 99, 205 men and 609 women. In ambulant, self-supporting subjects classified as ADL 1, women had higher H%, lower A%, and lower L% at each age group than in men. In subjects older than 60 years of age, H% increased and L% decreased markedly in women, whereas these changes were milder in men. Women, but not men, showed definite fall of L% and rise of H% along with the decrease of the level of activity. In hospitalized female subjects with a lower level of activity, but not in ambulatory female subjects, fall of L% and rise of H% was noted after 1 year, unlike the results in their male counterparts. Mineral distribution changes over the whole body characterized by age, gender, and activity may serve as new indices for evaluation of skeletal changes caused by aging, lifestyle, and disease.