Effects of estrogen/androgen therapy on bone mineral density parameters

Although estrogen's efficacy in reversing loss of bone mineral density (BMD) has been extensively documented, the role of androgens in preserving and restoring BMD is less well understood. Estrogen/androgen (E/A) therapy is especially important for surgically menopausal women. This population group experiences marked bone loss in response to the dramatic decline in ovarian hormones. The resulting hormonal profile differs significantly from that of naturally menopausal women. For surgically menopausal women, the relation of estrogens, androgens and sex hormone binding globulin (SHBG) is of special concern, as the interrelation between these hormones ultimately may reduce hormonal bioavailability. This paper reviews the relation of bone metabolism to ovarian hormones and the mechanics of BMD loss as well as the tools available to clinicians to assess bone loss in menopausal women. It further discusses androgen excess in women with polycystic ovary syndrome. Currently available hormonal regimens to preserve bone are described, including estrogen-only therapy, E/A therapy, tibolone and estrogen-progestogen therapy.