Other analyses
17-OH-progesteron
A precursor of cortisol from the adrenal glands; measured when an inborn disorder of the adrenal hormones (CAH) is suspected.
Everything about this testWhat it measures
17-OH-progesterone (17-hydroxyprogesterone) is an intermediate step in the production of cortisol in the adrenal glands. The next step requires the enzyme 21-hydroxylase. If that enzyme works less well, as in congenital adrenal hyperplasia (CAH, also called adrenogenital syndrome), 17-OH-progesterone builds up and the body makes more male hormones. The ovaries also make 17-OH-progesterone, especially in the second half of the cycle. The value follows a daily rhythm and is highest in the morning.
- The mild, non-classic form of CAH in women with excess hair growth, acne or irregular periods, to tell it apart from PCOS (polycystic ovary syndrome)
- Monitoring the treatment of known CAH, together with androstenedione
High
A slightly raised value is common without any disorder: after ovulation and in the second half of the cycle, during pregnancy, and when blood is drawn later in the day. A clearly raised value, measured in the morning early in the cycle, fits the non-classic form of CAH; the symptoms then closely resemble those of PCOS. In PCOS itself, 17-OH-progesterone is usually normal or at most slightly raised. In people with CAH who take hydrocortisone or another corticosteroid, a raised value usually means the dose or the timing of intake needs adjusting. A raised value is not a diagnosis on its own: whether it is CAH only becomes clear from a stimulation test or DNA testing.
Low
A low or normal value, measured in the morning early in the cycle, makes a non-classic form of CAH less likely. Use of corticosteroids, such as prednisone or hydrocortisone, lowers the value. In people with CAH under treatment, a low value can mean the dose is higher than needed. A low value causes no symptoms on its own.
Preparation
- Have your blood taken around 8:00 in the morning, because 17-OH-progesterone falls during the day. If you still menstruate, have it taken on day 2 to 5 of your cycle.
If your result is abnormal
With a raised value, the GP repeats the test at the right moment in the cycle or refers to an internist-endocrinologist or gynecologist. They can determine with an ACTH stimulation test and possibly DNA testing whether it is CAH. With a normal value and symptoms of excess male hormones, assessment for PCOS follows.
Reliability
17-OH-progesterone is a useful first step in detecting the non-classic form of CAH, but values in people with and without CAH overlap, especially if blood was not drawn at the right time. A raised value is therefore followed by a stimulation test with ACTH (a hormone that stimulates the adrenal gland) or DNA testing. The Dutch PCOS guideline (NVOG, 2023) asks for other causes of excess male hormones to be ruled out before PCOS is diagnosed; CAH is one of them.
Limitations
- Timing: because of the daily rhythm, the value is highest in the morning; the laboratory advises a blood draw around 8 a.m.
- Cycle: the value rises after ovulation. In women with a menstrual cycle, a measurement in the first days after the start of the period is easiest to interpret.
- Pregnancy raises the value; corticosteroids such as prednisone or hydrocortisone lower it.
- Reference values differ by laboratory, method, age and sex; only compare a result with the values of the same laboratory.
How common is this
The severe, inborn form of CAH is diagnosed in 12 to 15 children a year in the Netherlands, nowadays usually through the newborn heel prick test. The mild form only becomes noticeable after puberty, mainly through excess hair growth and menstrual problems in women, and is diagnosed in adulthood. In women with symptoms of excess male hormones, PCOS is by far the most common cause; the mild form of CAH is the cause in a small proportion of them.
Who is this useful for
Useful for women with excess hair growth, acne, irregular periods or other signs of excess male hormones, especially if the symptoms started early, if CAH runs in the family, or if there is doubt between PCOS and a cause in the adrenal glands. Also for people with known CAH, to monitor treatment in consultation with the treating specialist. The result means most when blood is drawn around 8 a.m. and, in women with a menstrual cycle, in the first days after the start of the period. Not useful for people without symptoms, and not as a measure of stress or tiredness.
Downsides and risks
- A measurement at the wrong time, late in the day or after ovulation, can give a falsely raised value and lead to unnecessary worry and follow-up tests.
Sources
Always discuss an abnormal result with your GP. If a result is strongly abnormal, we try to reach you as soon as possible. Read your result yourself as well and contact your GP if in doubt. A test does not make a diagnosis. Read more about risks and results