Urinary 17-Oxogenic and 17-Oxosteroids: A Case for Deletion from the Clinical Chemistry Repertoire

Abstract

The principal glucocorticoid secreted by the human adrenal cortex is cortisol, at a rate of about 60 !Lmol/ day ( Fig. 1). Less than 1 % of the secreted cortisol is excreted unchanged in the urine. Cortisol is metabolised in the liver, and the metabolites are excreted as water-soluble glucuronides (Fig. 2). Approximately 80 % of cortisol is excreted as 17-hydroxy-corticosteroids, and between 5 %and 10 %undergoes further catabolism and is excreted as ll-oxygenated 17-oxosteroids. In normal subjects, a small amount of the precursors of cortisol is secreted. 17ot-Hydroxyprogesterone is metabolised mainly to pregnanetriol and to 17ot-hydroxypregnanolone, while l l-deoxycortisol is metabolised mainly to tetrahydro ll-deoxycortisol and to pregnanetetrol. In pathological conditions where there is a deficiency of21-or l l-hydroxylase, the metabolites of 17ot-hydroxyprogesterone and l I-deoxycortisol form the major component of the 17-hydroxycorticosteroid metabolites excreted. As with cortisol metabolism there is some further catabolism of these steroids to give ll-deoxy 17-oxosteroids.17-0xosteroids arise not only from the metabolism of adrenal steroids and from adrenal secretion but also from the ovary and testis. 17-0xosteroids in urine therefore comprise a mixture of ll-oxy and ll-deoxy 17-oxosteroids of adrenal origin as well as l l-deoxy 17-oxosteroids of gonadal origin.

Urine steroid excretion rates in childhood reflect growth and activity of the adrenal cortex

“…The Porter-Silber and blue tetrazolium reactions used in earlier studies are non¬ specific methods that measure not only metabolites of cortisol but certain precursors as well as material unrelated to steroids. Few laboratories now offer these assays, preferring to measure selected ste¬ roids in blood by radioimmunoassay (12). Individ¬ ual steroids in urine have been quantified in the past after separation using paper or column chro¬ matography (13,14) or a combination of paper before gas liquid chromatography (15).…”