SEQUENTIAL ADDITION OF LOW-DOSE OF MEDROGESTONE OR MEDROXYPROGESTERONE ACETATE TO TRANSDERMAL ESTRADIOL - A PILOT-STUDY ON THEIR INFLUENCE ON THE ENDOMETRIUM

We evaluated bleeding pattern and endometrium following the administra tion of two of the most common types of progestogens used in hormone r eplacement therapy, medroxyprogesterone acetate (MPA) and medrogestone acetate. Twenty eight patients in spontaneous menopause were randomly allocated to two groups. Group 1 (n=14) received 5 mg/day of MPA and group 2 (n=14) received 5 mg/day of medrogestone: both the progestogen s were sequentially added for the last 12 days of a 21-day period of t ransdermal estradiol administration (50 mu g per day). A 7-day treatme nt-free period completed the cycle. The study treatments were administ ered for 6 cycles. The endomtria were checked for their thickness by t ransvaginal ultrasound before starting treatment and at 6th treatment cycle (days 6-10 of the estrogen-only phase and during the period betw een days 8 and 12 of the progestogen addition). Endometrial biopsies w ere performed before starting treatment only in the patients with a po sitive progesterone challenge test and in all the patients at the end of the study during the addition of the progestogen. The bleeding patt ern was closely monitored. MPA is accompanied by a thick endometrium w ith full secretory transformation in all cases. On the contrary, the s ame dose of medrogestone induced a consistent decrease of estrogen pri med endometrium with only 4 cases of full secretory transformation. Fo ur medrogestone-treated patients dropped out due to unscheduled bleedi ng. A low dose of medrogestone added to transdermal estradiol induced incomplete transformation of endometrium and oligo-amenorrhea more fre quently than MPA, but it increased the chances of irregular bleeding. MPA fully transformed the endometrium: periods were thus heavier but r egular. None of the patients in either group had endometrial hyperplas ia.