Markedly elevated in patients with congenital adrenal hyperplasia (adrenogenital syndrome) due to 21-hydroxylase deficiency; evaluate hirsutism and/or infertility; assess certain adrenal or ovarian tumors with endocrine activity
17-OH-progesterone is the substrate for subsequent 21- and 11-hydroxylation to produce cortisol. The two critical enzymes, 21-hydroxylase and 11-β-hydroxylase, participate in cortisol generation. If hydroxylation, at either position, cannot take place because of enzyme deficiency, cortisol synthesis decreases, accompanied by increased ACTH. Congenital adrenal hyperplasia and adrenogenital syndrome result from lack of normal glucocorticoids and buildup of precursors (mostly virilizing). Lack of 21-hydroxylase is the most common cause of adrenogenital syndrome. Congenital adrenal hyperplasia caused by 21-hydroxylase deficiency is the most common cause of female hermaphroditism. It is an autosomal recessive disorder. Basal 17-hydroxyprogesterone levels can be normal in late-onset 21-hydroxylase deficiency presenting as hirsutism. Such patients are described as having dramatically increased 17-hydroxyprogesterone response to ACTH. Patients with 21-hydroxylase deficiency have increased 17-ketosteroids, urine pregnanetriol, as well as high 17-hydroxyprogesterone. Prenatal diagnosis of congenital adrenal hyperplasia is possible by HLA typing, by DNA analysis, or by hormone measurements from amniotic fluid, including 17-hydroxyprogesterone. Some nonspecificity is seen when amniotic fluid analysis is used. Congenital adrenal hyperplasia with adult onset is among the causes of hirsutism and/or infertility.