Development of plasma 21-deoxycortisol radioimmunoassay and application to the diagnosis of patients with 21-hydroxylase deficiency.

Specific 21-deoxycortisol (21-DF) antiserum was raised in New Zealand white rabbits using a 21-DF-3,20-oxime-bovine serum albumin complex. Plasma radioimmunoassay of 21-DF was developed and used together with a radioimmunoassay of 17-hydroxyprogesterone (17-OH-P) for diagnosis of patients with 21-hydroxylase deficiency of congenital and postpubertal forms. The assays were performed in plasma extracts after isolation by paper chromatography. The response of plasma 21-DF and 17-OH-P to i.v. ACTH (25 IU) was studied in 15 adult controls and compared to 8 women with the late onset form of 21-hydroxylase deficiency and 23 women with idiopathic hirsutism. Normal 21-DF values for women were 6.9 +/- 3.6 ng/dl and for men 9.71 +/- 2.73 ng/dl. Newborn children (age: 3-10 days) had a value of 8.3 +/- 4.8 ng/dl. These values are definitely lower than the lowest value ever published. This is possibly due to the specificity of the antibody. During the menstrual cycle the 21-DF values did not change. The baseline and post-stimulated concentrations of hormone were similar in controls and women with hirsutism but were significantly higher in women with the late onset form of 21-hydroxylase deficiency. In the congenital form of 21-hydroxylase deficiency the 21-DF values (baseline) were high. In general, the 21-DF and 17-OH-P values have shown parallel changes. However, one case of 21-hydroxylase deficiency with elevated 21-DF but normal 17-OH-P was observed. The use of 21-DF for the diagnosis of 21-hydroxylase deficiency is suggested.