OESTRIOL METABOLISM IN PREGNANT WOMEN

Abstract

ABSTRACT Oestriol-16-14C was administered intravenously to four pregnant women prior to sterilisation and surgical interruption of pregnancy and the quantity and nature of radioactive metabolites in the products of conception, systemic venous blood and urine were studied. Thirty minutes following the injection of the isotope, less than 0.5 per cent of the administered dose was found in the amniotic fluid, foetus and placenta. Approximately 40 per cent of the radioactive material recovered from the systemic venous blood withdrawn 10 to 30 minutes following injection was unconjugated (free) oestriol. Some 15 per cent of the circulating radioactive material was identified as oestriol-3-sulphate and almost 10 per cent behaved as oestriol-3-sulphate,16(17?)-glucosiduronate. Oestriol-16(17?)-glucosiduronate was also detected, but only in minute quantities (0.5 per cent of total). The rest of the circulating radioactive material was present as unidentified »polar conjugates«. Urine specimens collected over various intervals revealed a changing pattern of conjugation. Oestriol and oestriol-3-sulphate were present only in very small amounts in all specimens studied. The bulk of radioactive material was excreted as oestriol-16(17?)-glucosiduronate and as so-called »polar glucosiduronates« (consisting of di- and perhaps triglucosiduronates of oestriol), accompanied by small, but significant, amounts of oestriol-3-sulphate,16(17?)-glucosiduronate-like radioactive material. As time passed following injection of the isotope, the amount of »polar glucosiduronates« present in the urine increased markedly. This was associated with a corresponding decrease in the amount of oestriol-16(17?)-glucosiduronate. At least 99 per cent of the oestrogen moiety of the urinary radioactive material consisted of oestriol. The recovery of radioactivity from the urine, collected during 72 hours, was low, ranging from 41 to 47 per cent.