The origin of oestrogens in men is only partly understood. From infusion studies with radioactively labelled hormones, we know that oestradiol (E2) and oestrone (E1) are either directly secreted by the testes and adrenal glands or peripherally produced from testicular or adrenal androgens. We determined E2, E1, androstenedione, testosterone and dehydroepiandroster-one sulphate (DHEAS) in 292 elderly men and 367 postmenopausal women. We considered post-menopausal women as men without testes, assuming that the postmenopausal ovary is not endocrinologically active and that the testes do not contribute to circulating levels of DHEAS. Subjects were stratified by DHEAS levels to adjust for differences in DHEAS levels between sexes. For men and women separately, mean levels of E2, E1, androstenedione and testosterone were calculated per DHEAS stratum. The relative direct and indirect contributions of the testes to steroid levels in men were calculated by the formula [(C(m) - C(f))/C(m)] x 100%, in which C(m) and C(f) represent the mean concentrations of the steroid in men and women respectively. The relative contributions (%) of the testes to hormone levels per DHEAS stratum (<2, 2-4, 4-6 and >6 micromol/l) respectively were, for E2, 72%, 60%, 52% and 44%; for E1, 54%, 47%, 35% and 34%; for androstenedione, 14%, 4%, 12% and 0%; and, for testosterone, 88%, 88%, 87% and 83%. We conclude that in elderly men dependent on DHEAS levels, 44-72% of E2 and 34-54% of E1 originate directly or indirectly from the testes.
