Secondary
amenorrhea in women with normal
estrogen levels increases the risk of
endometrial carcinoma. Cyclical
dydrogesterone induces regular withdrawal
bleeding and effectively protects the endometrium of postmenopausal women receiving
estrogens. In order to assess the efficacy of
dydrogesterone in inducing regular withdrawal bleeds in premenopausal women with secondary
amenorrhea or
oligomenorrhea and normal
estrogen levels, a double-blind, randomized, placebo-controlled, multicenter study was conducted in 104 women using cyclical
dydrogesterone as is used for
estrogen replacement therapy. Treatment consisted of
dydrogesterone (10 mg/day on days 1-14 followed by placebo on days 15-28 of each cycle) given for six cycles of 28 days. The control group received placebo throughout the six cycles.
Bleeding was documented by the patient on diary cards. The number of women with withdrawal
bleeding during the first cycle was twice as high in the
dydrogesterone group as in the placebo group (65.4% vs. 30.8%; p = 0.0004). Superiority of
dydrogesterone was also observed for regularity of
bleeding over the six cycles (p < 0.0001), although endometrial thickness after six cycles did not differ between the groups. In conclusion,
dydrogesterone is significantly superior to placebo in inducing withdrawal
bleeding, and maintaining regular
bleeding, in women with secondary
amenorrhea and normal
estrogen levels.