Clinical use of progestins in the menopausal patient: dosage and duration.

Although estrogens are the principal hormone needed by postmenopausal women, there are many benefits of progestins. There is some increased risk of endometrial cancer from estrogen-replacement therapy; however, added progestin decreases this risk to less than that observed in untreated postmenopausal women. Climacteric women at the greatest risk of endometrial cancer can be identified by the progestin challenge test. There may also be some protection from breast cancer in progestin-treated postmenopausal women. Progestins are effective in managing the increased breast tenderness and aggravation of fibrocystic breast disease that may occur in some estrogen-treated postmenopausal women. Both estrogens and progestins are effective in retarding the progression of osteoporosis, but estrogen-progestin combination therapy may promote new bone formation. Long-acting injectable progestins are effective in relieving vasomotor symptoms. Finally, progestins also reduce the incidence of postmenopausal bleeding and the necessity of diagnostic curettage. The progestin should be continued for ten days each month as long as the patient experiences withdrawal bleeding. When withdrawal bleeding ceases, the progestin may be discontinued. However, the progestin challenge test should be repeated annually to ensure that the endometrium is not being stimulated by either exogenous therapy or increased endogenous estrogens.