Bone mineral content in relation to age and menopause in middle-aged women. A study of bone density in lumbar vertebrae by dual photon absorptiometry in a population sample of women.

As one phase of a comprehensive population study of women, bone density was determined in the third lumbar vertebra by dual photon absorptiometric technique. The method involves the use of two radionuclides, which both emit gamma radiation but with different energies (241Am with 59.6 keV and 137Cs with 662 keV). Women in three age strata were studied: 46, 54 and 62 years. The bone mineral content was higher in premenopausal or recently postmenopausal 54-year-old women than in women of the same age who had been postmenopausal for a long time (p less than 0.02). A similar trend was found for women aged 62. The differences could not be explained by differences in other factors studied, such as body height, body weight, smoking habits, numbers of pregnancies or physical inactivity. No significant differences were found when women with similar menstrual status in different age-groups were compared. In the ages studied, hormonal factors seem to be more important than the age per se for the development of oeteoporosis.