Effect of Treatment with Estrogen Conjugates on Endogenous Plasma Steroids

Abstract

Plasma dehydroepiandrosterone sulfate (DS), androstencdione (A₂), estrone plus estradiol (E₁₊₂) and estriol (E₃) were measured in women treated with conjugated estrogens and controls. Plasma DS, A₂, and E,₊₂ levels were higher in the premenopausal controls than in the untreated postmenopausal women; E₃ levels were below the sensitivity of the assay. Estrogen conjugates, 1.25 mg or 2.5 mg daily, increased plasma E₁₊₂ to levels similar to those in premenopausal untreated women, and E_a became readily assayable. A 0.625-mg dose increased the level of E₃ without affecting E₁₊₂; consequently, the plasma E_a/E₁₊₂ ratio was elevated. It is concluded that at the lowest dose 16 a-hydroxylase activity, perhaps by substrate induction, is sufficient for the exogenous estrogens to be largely metabolized to E₃. Estrogen conjugates had no detectable effect on plasma DS or A₂.