METABOLISM OF 17β-OESTRADIOL-4-14C IN EARLY INFANCY

Abstract

ABSTRACT The urinary metabolites of intramuscularly administered 17β-oestradiol-4-14C were studied in three infants born with multiple malformations. Of the radioactive material recovered from the urine less than 5 per cent was in an ether-soluble (»free«) form. Following enzyme hydrolysis, an average of 46 per cent became ether-extractable. Of the remaining material all but some 2 per cent was butanol-soluble. The pattern of urinary metabolites was similar in all subjects. Oestrone, 17β-oestradiol and possibly 2-methoxyoestrone accounted for less than 5 per cent of the total urinary radioactive material. Oestriol, 16α-hydroxyoestrone and 16-oxo-17β-oestradiol comprised an important group of metabolites, representing together some 20 per cent of the total. However, the quantitatively most important metabolite was a hydroxylation product somewhat more polar than 2-hydroxyoestriol. This compound accounted for 16 per cent of the total. It is concluded that the metabolism of 17β-oestradiol in early infancy is characterized by extensive hydroxylation reactions. This pattern of metabolism may indicate one of the mechanisms by which the foetus is protected against steroids with high biological activity.