Relative value of transdermal and oral estrogen therapy in various clinical situations

In this study, we reviewed the comparative effectiveness of transdermal and oral estrogen therapy in various groups of women.

On the basis of published data and personal clinical experience, we compiled recommendations for use of the various modes of estrogen replacement therapy.

The use of injectable estrogen or implantable estrogen pellets can no longer be recommended because of their expense, inconvenience, and unphysiologic pattern of serum estrogen response. The two main estrogen preparations currently used in the United States--orally administered conjugated estrogens and transdermally administered estradiol--undergo different metabolism, and these processes are reflected in differing levels of circulating hormones and hepatic by-products, including blood clotting factors, binding proteins, renin substrate, and apolipoproteins, and in varied composition of the bile.

At least theoretically, transdermal estrogen therapy might be more beneficial than oral estrogen therapy for women who smoke cigarettes or who have migraine headaches, hypertriglyceridemia, hepatobiliary disorders, fibrocystic breast disease, or a history of thromboembolism. In contrast, women with hypercholesterolemia might respond better to oral than to transdermal estrogen therapy.

Additional properly designed clinical studies are necessary before these recommendations for estrogen replacement therapy can be validated or refuted.