Capillary gas chromatography as a tool for characterization of urinary steroid excretion in patients with congenital adrenal hyperplasia

Abstract

Urinary steroid excretion was studied by capillary gas chromatography in 23 patients with congenital adrenal hyperplasia. In 5 patients the estimated excretion rates of pregnanetriol were in or below the normal range and 7 patients presented supranormal excretion rates of tetrahydro-cortisone and/or other glucocorticoid metabolites. Deficiency of 21-hydroxylase was nevertheless demonstrated in each patient by an increased ratio of excreted precursors vs products of 21-hydroxylase, e.g. of pregnanetriol/tetrahydro-cortisone. Due to this relative deficiency of glucocorticoids the patients' steroid excretion was further characterized by a predominance of 5 alpha-hydrogenated C19O3 metabolites (11-keto-androsterone, 11-hydroxy-androsterone) over their 5 beta-hydrogenated homologues (11-keto-etiocholanolone, 11-hydroxy-etiocholanolone). An apparent preponderance in the excretion of pregnenetriol over that of pregnanetriol was found in 4 patients, but the presence of pregnenetriol was not confirmed by mass spectrometry following prepurification of the urine samples by thin-layer chromatography indicating interference of an unidentified steroid metabolite with the initial gas chromatographic analysis. The simultaneous determination of steroids serving as precursors or products of 21-hydroxylase by capillary gas chromatography helps to establish the diagnosis of 21-hydroxylase deficiency and to characterize the pattern of steroid excretion in this syndrome even in patients where the estimation of single urinary steroids may lead to erroneous conclusions.