ENDOGENOUS SEX STEROIDS AND BONE-MINERAL DENSITY IN OLDER WOMEN AND MEN - THE RANCHO BERNARDO STUDY

This study examines the associations between endogenous sex steroids a nd bone mineral density (BMD), using data from a geographically define d cohort in Rancho Bernardo, California. Participants were community-d welling women and men aged 50-89 years who took part in a study of end ogenous sex steroid measurement between 1984-1987 and who had BMD meas ured in 1988-1991. Those taking corticosteroids or estrogen at the tim e of sex steroid determination were excluded. The main study outcomes were BMD of the ultradistal radius, midshaft radius, lumbar spine, and total hip by sex steroid level, adjusted for age, body mass index, ci garette smoking, alcohol consumption, leisure exercise, use of thiazid es, thyroid hormones, and former estrogen use (women only). At the tim e of the hormone measurements, the mean age of the 457 women was 72.1 years and that of the 534 men was 68.6 years. A statistically signific ant positive relation was seen between bioavailable estradiol and BMD at all sites in women and men. Total estradiol was significantly assoc iated with BMD at all sites in women and at all but the ultradistal ra dius in men. Estrone had a global effect on BMD in women and was not m easured in men. Higher bioavailable (but not total) testosterone level s were associated with higher BMD of the ultradistal radius, spine, an d hip in men and the ultradistal radius in women. Dehydroepiandrostero ne was positively associated with BMD of the midradius, spine, and hip in women and was not associated with BMD at any site in men, Of the s ex steroids tested, bioavailable estrogen was most strongly associated with BMD in both women and men. We conclude that endogenous sex stero id levels are significantly related to bone density in older women and men. Individual variation in age-related bone loss may be partially a ccounted for by alterations in sex steroid levels with aging. Further study to elucidate safe environmental and medical methods to maintain optimal sex steroid levels in old age is needed.