This application is for continuation of our studies on the direct association of endogenous estrogen and androgen levels to bone. Our first studies examined the relationship of endogenous sex steroid hormone concentrations to appendicular cortical bone, specifically the dominant radius, in 174 normal postmenopausal woman, mean age 58 years. All of the woman were participants in a clinical trial designed to determine the effects of walking on postmenopausal bone loss. There was little relationship between androgen hormones, testosterone and androstenedione to cortical bone. Estrone concentrations, the primary postmenopausal estrogen were, however, significant predictors of cortical bone in these women. Our previous analyses had suggested that milk consumption during childhood and adolescence was related to bone density postmenopausally. We, therefore, combined both determinants of peak skeletal mass, namely early milk consumption, and determinants of bone density, namely density postmenopausally. In a subsequent study in 100 perimenopausal women we again demonstrated that early age calcium intake is directly related to bone density using dual photon absorptiometry. In a small sample of older postmenopausal women we have found that black women had greater bone density than white women. In the current proposal, we would like to extend these observations (1) to women in the immediate postmenopausal period; (2) to elderly women in the late postmenopausal period and (3) to black postmenopausal period. In addition, we propose to study not only the relationships to cortical bone, but also to trabecular bone. These studies as in the previous grant will make use of existing data bases for most of the information and represents an efficient way to substantially expand our understanding of the relationship of endogenous sex steroid concentrations and calcium intake to bone density. The sex steroids of interest include estrone, estrone sulfate, estradiol, testosterone, and androstenedione. We will test the hypothesis that both cortical and trabecular bone are primarily determined by dietary intake of calcium during periods of increasing and stable bone mass and the levels of endogenous estrogens in the blood.
