Radioimmunoassay of three deoxycorticoids in human plasma following HPLC separation

A radioimmunoassay of three deoxycorticoids, namely 11 beta,17 alpha-dihydroxy-4-pregnene-3,20-dione (21-deoxycortisol), 17 alpha,21-dihydroxy-4-pregnene-3,20-dione (11-deoxycortisol), and 21-hydroxy-4-pregnene-3,20-dione (11-deoxycorticosterone) which are important for differential diagnosis of congenital adrenal disorders, is described and evaluated. Antisera against 3-(O-carboxymethyl)oximes conjugated to bovine serum albumin were raised in rabbits. The radioligands were prepared by radioiodination of previously synthesized homologous tyrosine methyl ester derivatives. Following diethyl ether extraction, the steroids were separated from each other and from cross-reactants by HPLC using a Nucleosil C8 reverse-phase column and a methanol-water mixture (7:5, v/v) as an eluent. Normal levels of analyzed steroids ranged from 0.02 to 0.348, 0.185 to 3.80, and 0.013 to 0.299 nmol/l, for 21-deoxycortisol, 11-deoxycortisol and 11-deoxycorticosterone, respectively. The levels of both deoxycortisols rose significantly after ACTH treatment. Data are given with respect to the concentrations of these steroids in some pathological situations such as 21-hydroxylase and 11 beta-hydroxylase block, hyperaldosteronism, and polycystic ovary syndrome.