METABOLISM OF OESTRIOL-3-SULPHATE AND OESTRIOL-16(17?)-GLUCOSIDURONATE IN PREGNANT WOMEN

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Abstract
A combination of oestriol-15-H3-3-sulphate (OE3-15-H3-3S) and oestriol-16-Cl4-16(17?)-glucosiduronate (OE3-16-C14-16(17?) Gl) was administered in the form of a continuous intravenous infusion over 310 and 280 min, respectively, to 2 women at midpregnancy prior to the interruption of gestation. Eighty and 66% respectively, of the administered H3-labelled material and 87 and 83% respectively, of the C14-labelled material was recovered within 24 hours from the urine of the 2 subjects. H3-labelled OE3-3S and both H3- and 14C-labelled OE3-16(17?)G1 and oestriol-3-glucosiduronate (OE3-3G1) were isolated from the urine of both patients in a radiochemically homogeneous form. No C14-labelled material was found in the OE3-3S isolated. During the continuous infusion period, some 26% of the urinary H3-labelled material was excreted as OE3-3S, 68% was present as OE3-16(17?)G1 and 6% as OE3-3G1. Corresponding proportions of the Cl4-labelled urinary material were 97% OE3-16(17?)G1 and 3% OE3-3G1. During the postinfusion period, the pattern of urinary conjugates showed a marked change: only 2% of the H3-labelled material was excreted as OE3-3S, 31% was OE3-16(17?)G1 and as much as 67% was OE3-3G1. Corresponding figures for the Cl4-labelled material were: 33% OE3-16(17?)G1 and 67% OE3-3G1. No radioactive oestrogens other than OE3 were detected. The endogenous urinary estriol (OE3) excretion during the 24 hours of experiment (expressed in OE3-equivalents) was: 0.086 mg OE3-3S, 1.87 mg OE3-16(17?)G1 and 1.57 mg of OE3-3G1 in the first subject and 0.13 mg OE3-3S, 3.01 mg OE3-16(17?)G1 and 1.53 mg of OE3-G1 in the second patient. From the relationship between the specific activities of the injected and isolated oestriol conjugates the amount of OE3-3S and OE3-16(17?)G1 reaching the maternal circulation during 24 hours was calculated. On basis of these values it is concluded that in midpregnancy the bulk of estriol conjugates in the blood consists of glucosiduronates rather than of sulfates and that OE3-3G1 is a quantitatively important urinary metabolite not only of circulating OE3, but also of OE3-3S and OE3-16(17?)G1.