Bioavailable estradiol in man: relationship with age and testosterone.

Sex hormones undergo decreases in aging men. Several studies have shown the association of low levels of bioavailable estradiol with osteoporosis in man. To allow a better approach of sex hormones influences, we evaluated bioavailable estradiol concentrations in men and its correlation with age and testosterone. We show that bioavailable estradiol decreases significantly with age. We provide reference values in men with normal testosterone levels.