Transdermal hormonal replacement therapy with transdermal progestin every second month

Unopposed estrogen therapy may induce endometrial hyperplasia. To protect the endometrium, estrogen replacement therapy should be combined with a progestin in menopausal women with an intact uterus. The aim of this open non-comparative study was to evaluate the effects on bleeding control and endometrium of 'spacing-out' the 14-day progestin therapy to every second month during transdermal combined hormonal replacement therapy.

Sixty-eight healthy women, previously treated with sequential combined transdermal hormonal replacement therapy every month for 3 years, were treated for the following 2 years in cycles with 6 weeks of transdermal estradiol 50 micrograms/daily (Estraderm, Ciba-Geigy), followed by 2 weeks of combined norethisterone acetate 0.25 mg/day and 50 micrograms estradiol per day.

Annual endometrial biopsies diagnosed hyperplasia in one woman during the second year whereas most biopsies showed a secretory endometrium. Vaginal ultrasound showed no correlation to either bleeding-pattern or histopathological diagnosis. Most women had a regular bleeding-pattern.

Transdermal progestin every second month might be an alternative to regular monthly sequential hormonal replacement therapy.