Urinary Metabolites of Estradiol and Estriol Administered Intra-amniotically

Abstract

A mixture of tritiated estriol and ¹⁴C-estradiol was administered intra-amniotically to a subject who, at the 14th week of gestation, was scheduled for therapeutic abortion and sterilization. Estrone (E₁), estradiol (E₂), 16-epiestriol (16-epi-E₃), estriol (E₃), 16-keto-estradiol (16-keto-E₂) and a tetrol (E₄) were isolated from the pool of urine collected for 64 hr following the injection. The isotope ratios in these metabolites were determined and minimal values for the fractions of the injected doses excreted in each compound were estimated. The results indicate that both tracers were converted to E₄ and suggest that the conversion of E₂ to E₄ occurs only partially via E₃. The most abundant urinary product derived from the administered tracer of E₂ wasestetrol (E₄).