17-hydroxyprogesterone is formed from progesterone in the adrenal glands (mostly as an intermediary substance on the way to making the adrenal's main hormone, cortisol) and in the ovaries (on the way to making androgens and estrogens). A congenital lack of one or other of the enzymes needed to make cortisol in the adrenal causes androgens to be made instead, in turn causing hirsutism and oligomenorrhea in women, maybe with the polycystic ovary syndrome (in mild cases), or (in severe cases) causing intersex at birth. The adrenal glands enlarge in an attempt to maintain production of cortisol (hence congenital adrenal hyperplasia, CAH). An inappropriately high level of 17-hydroxyprogesterone in serum is diagnostic of CAH.

(CAH) Enlargement and abnormal function of the adrenal glands, usually from before birth, owing to a genetically determined, partial block in the production of cortisol, the adrenal glands' main hormone, resulting in overproduction of subsidiary hormones, including androgens, tending to virilise the female fetus, which can present at birth with intersex. In mild forms does not manifest until puberty, when the symptoms of oligomenorrhea and hirsutism mimic those of polycystic ovary syndrome. See also serum 17-hydroxyprogesterone.