Biochemical studies on endometrium from postmenopausal women receiving hormone replacement therapy.

Nuclear oestrogen-receptor and soluble progesterone-receptor have been measured in postmenopausal endometria from women receiving either Premarin or Premarin plus norethisterone. Oestradiol dehydrogenase has been measured in some samples. It is concluded that the doses of Premarin currently in use have a potent oestrogenic effect on the endometrium. Norethisterone does not affect the amount of oestrogen entering the nucleus but it may temporarily suppress the biological activity of the oestrogen.