17-hydroxyprogesterone (17-OHP)
A steroid hormone made by the adrenal glands, used mainly to diagnose congenital adrenal hyperplasia — an inherited enzyme problem in which 17-OHP builds up. It also features in the work-up of excess male-type hormones in women.
What it measures
17-hydroxyprogesterone (17-OHP) is a steroid made in the adrenal glands as an intermediate step on the pathway toward cortisol. Its main clinical use is in diagnosing congenital adrenal hyperplasia (CAH), a group of inherited conditions in which one of the enzymes needed to make cortisol is deficient — most commonly 21-hydroxylase. When that enzyme is missing, the steroid pathway is blocked just at the point where 17-OHP is converted onward, so 17-OHP accumulates and is diverted into making androgens (male-type hormones). A markedly raised 17-OHP is therefore the key marker of CAH: very high levels appear in the severe form that presents in newborns (part of newborn screening in many countries), while milder, non-classic CAH can present later with early puberty, acne, excess hair or fertility problems, and is picked up by a raised 17-OHP, sometimes only after a stimulation test. Because 17-OHP naturally varies with the time of day, the menstrual cycle and sex, the sample timing matters and the result is interpreted with cortisol, ACTH and androgens such as testosterone and DHEAS. It is a targeted, specialist test rather than a general hormone screen.
What a high value can mean
- Congenital adrenal hyperplasia (CAH) — the main reason for a raised level; a markedly high 17-OHP points to a 21-hydroxylase enzyme deficiency.
- Non-classic (late-onset) CAH — a milder rise, often found during a work-up for excess androgens; may need a stimulation test.
- An adrenal tumour — uncommonly, a hormone-producing adrenal growth.
- Timing effects — levels are naturally higher in the morning and vary with the menstrual cycle.
What a low value can mean
- Normal — the expected result; makes congenital adrenal hyperplasia unlikely.
- A controlled level on treatment — in someone known to have CAH, shows the treatment dose is appropriate.
When to discuss with a doctor
17-OHP is a targeted test, requested to diagnose or monitor congenital adrenal hyperplasia, or as part of investigating signs of excess androgens — such as early puberty in a child, or irregular periods, acne and excess hair in a woman where the pattern does not fit typical PCOS. A markedly raised level points to CAH and leads to specialist (endocrine) assessment, sometimes with a stimulation test to confirm milder forms; in someone already diagnosed, it helps guide the treatment dose. Because levels vary with time of day, cycle and sex, correct timing and expert interpretation matter. Mediora.AI shows 17-OHP alongside cortisol, ACTH, testosterone and DHEAS so the adrenal and androgen pattern is read together; the diagnosis and treatment belong with your doctor and an endocrinologist.