17-OH progesterone (17-OHP) is a steroid hormone produced by adrenal glands. It is an immediate precursor to 11-desoxycortisol (Cpd-S) and is produced by its hydroxylation. 17-OHP is a significant indicator of the activity of the enzyme 21-hydroxylase, which is involved in the synthesis of steroid hormones cortisol and aldosterone. Excess synthesis of 17-OHP is seen in a condition called as 21-hydroxylase deficiency, which is the most common type of congenital adrenal hyperplasia (CAH). Thus 17 OHP is valuable for initial diagnosis of CAH.
17-0H Progesterone is also a useful test for screening infants with ambiguous genitalia for Congenital Adrenal Hyperplasia (CAH). This test is also done in cases of male infertility, girls with peripubertal virilization, children with premature adrenarche (wherein, the value of 17-0HP is increased without or after ACTH stimulation). For diagnostic purpose, results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings.