Multicomponent gas chromatographic analysis of urinary steroids excreted by an infant with a defect in aldosterone biosynthesis

Abstract

The urinary steroids excreted by an infant with a salt-wasting syndrome due to a suspected defect in the 18-oxidation of corticosterone have been analysed by gas chromatography-mass spectrometry. The excretion of tetrahydroaldosterone was low (3.5 mug/24 h) whilst the excretion of 3alpha,11beta,21-trihydroxy-5alpha-pregnan-20-one (allo-tetrahydrocorticosterone) and other corticosterone metabolites was high (total about 2 mg/24 h). The excretion of cortisol metabolites was apparently normal for age (total about 2 mg/24 h) but 3alpha,11beta,17alpha,21-tetrahydroxy-5alpha-pregnan-20-one (allo-tetrahydrocortisol) rather than tetrahydrocortisone, was the major component of the group. The excretion of an 18-hydroxycorticosterone metabolite 3alpha,18,21-trihydroxy-5beta-pregnane-11,20-dione (18-hydroxytetrahydroCompound A) was higher than normal for infants of this age (between 50 and 200 mug/24 h), suggesting that the defect was in 18-hydroxysteroid dehydrogenase rather than 1,-hydroxylase. In addition, 18-hydroxytetrahydrocorticosterone, another metabolite of 18-hydroxycorticosterone was tentatively identified and it was found that the rate of excretion of this compound was of similar magnitude to 18-hydroxytetrahydroCompound A. The salt balance of the infant has been sucessfully controlled by salt administration (77 mEq./24 h) and treatment with Fludrocortisone (0.5 mg/day).