COMPARISON OF THE METABOLISM OF OESTRIOL-3-GLUCOSIDURONATE AND OESTRIOL-16-GLUCOSIDURONATE IN PREGNANT WOMEN

Abstract

ABSTRACT Tritium-labelled oestriol-3-glucosiduronate (OE3-3Gl) and 14C-labelled oestriol-16-glucosiduronate (OE3-16Gl) were infused together over a 6 hour period to two pregnant women at midterm. The urinary metabolites were then isolated and identified. Ninety-one per cent of the 3H- and more than 77% of the 14C-labelled material were excreted in the urine within 24 hours. Only 2.2% of the 3H-labelled material recovered was present as OE3-16Gl, the rest was eliminated unchanged. In contrast more than 13% of the 14C-labelled material excreted was present as OE3-3Gl. No labelled oestriol-17-glucosiduronate (OE3-17Gl) could be detected. The urinary output of circulating OE3-3Gl was faster than that of OE3-16Gl. From the relationship of the specific activities of the infused and isolated OE3-3Gl and OE3-16Gl the amounts of these compounds reaching the maternal circulation hourly were calculated. On the basis of these estimates it is inferred that at midterm OE3-3Gl is a quantitatively important circulating oestriol conjugate and that it represents an end-product in oestriol metabolism.