Effects of an Antiestrogen on Subfractions of HDL Cholesterol during Estrogen Replacement Therapy

Abstract

The antiestrogenic effects of tamoxifen and estriol were compared in 39 postmenopausal women during estrogen replacement therapy. Subfractions of HDL [high density lipoprotein] cholesterol and its apolipoproteins and the serum levels of 2 estrogen sensitive liver proteins were followed during 3 cycles of unopposed estrogen therapy with 10 .mu.g ethinyl estradiol daily. During the last 10 days of the following 3 cycles the women received sequential addition of either 10 mg tamoxifen twice daily or 2 mg estriol twice daily. Tamoxifen clearly reduced the estrogen-induced increase of apolipoprotein AI, HDL2 cholesterol and total HDL cholesterol. In comparison the pregnancy zone protein and sex hormone-binding globulin were more sensitive to the estrogenic as well as to the antiestrogenic effect than the lipoproteins. Tamoxifen also counteracted the therapeutic effect on climacteric symptoms and its seems unlikely that this compound may be clinically useful as an alternative to progestogens during estrogen replacement therapy. The sequential addition of estriol had no apparent effects as compared to unopposed estrogen treatment.