Oestrogen concentrations in plasma, endometrium, myometrium and vagina of postmenopausal women, and effects of vaginal oestriol (E3) and oestradiol (E2) applications.

Oestradiol (E2), oestriol (E3) and oestrone (E1) levels were measured in plasma and endometrium, myometrium and vagina of 29 postmenopausal women who underwent hysterectomy. The influence of vaginal E3, compared to vaginal E2 therapy at a dose one-tenth that of E3 on the basal steroid levels was examined. We found (1) no correlation between basal tissue and plasma concentrations of the oestrogens in untreated postmenopausal women, however, after vaginal E3 therapy we did find a positive correlation between them, (2) E2 to be the oestrogen in the highest basal concentration in endometrium and myometrium as well as in the vagina, (3) higher basal concentrations of all three oestrogens in endometrium compared to myometrium and vagina, (4) a long term (at least 12 h) elevation of the plasma and tissue E3 concentrations after vaginal E3 therapy (0.5 mg per day), (5) no significant changes of the plasma and tissue E2 concentrations after 0.05 mg per day vaginal E2 therapy, measured 12 h after the last application and (6) no signs of a difference between vagina and uterus in uptake and retention of E3 or E2. In conclusion, there was no difference on this level of mechanism of action in vagina and uterus which can account for the supposed vaginotrophicity and non-uterotrophicity observed with E3 but not E2.