Low levels of estradiol are associated with vertebral fractures in older men, but not women: The Rancho Bernardo study

This longitudinal study included 288 postmenopausal women without estrogen use (median age, 72 yr) and 352 men (median age, 66 yr). All were community -dwelling, ambulatory, and Caucasian. Blood for hormone assays (total and b ioavailable estradiol and testosterone, estrone, androstenedione, dihydrote stosterone, dehydroepiandrosterone, and dehydroepiandrosterone sulfate) was obtained in 1984-1987, and vertebral fractures were diagnosed from lateral spine radiographs obtained in 1992-1996. At least one vertebral fracture w as found in 21% of women and 8% of men. Among men, age-adjusted hormone lev els differed by fracture status only for total (64.1 us. 75.4 pmol/L, P = 0 .012) and bioavailable (43.0 us. 51.4 pmol/L, P = 0.008) estradiol. There w as a graded association between higher concentrations of total and bioavail able estradiol and lower fracture prevalence (trend P < 0.01 for both hormo nes). Men with total testosterone levels compatible with hypogonadism (<7 n mol/L) were not more likely to have vertebral fractures. In women, none of the measured sex hormones was associated with vertebral fractures. There wa s also no increased prevalence of fractures in women with estradiol levels below the assay sensitivity (<11 pmol/L). These data suggest that estrogen plays a critical role in the skeletal health of older men and confirm other studies showing no association of postmenopausal endogenous estrogen level s with vertebral fractures in older women.