17-Hydroxyprogesterone
Adrenal hormone precursor that the body converts into cortisol
Also known as
Definition
17-hydroxyprogesterone (17-OHP) is a precursor that the adrenal glands convert into cortisol with the help of the enzyme 21-hydroxylase; the sex glands also produce it. If the enzyme is lacking because of an inherited gene change, 17-OHP builds up and is increasingly converted into male sex hormones. The blood test is mainly used to detect the most common form of congenital adrenal hyperplasia (CAH) and to follow its course.
| Parameter | Value |
|---|---|
| Unit | ng/dl or nmol/l |
| Reference Range | Adult women: up to about 290 ng/dl (8.8 nmol/l), depending on the menstrual cycle phase | Adult men: up to about 139 ng/dl (4.2 nmol/l). Labs differ; the range printed on your report is what counts, and your doctor interprets the result. |
Agree on your personal target range with your doctor.
Conversion: 1 ng/dl ≈ 0.0303 nmol/l; 1 nmol/l ≈ 33 ng/dl. Newborns, babies with low birth weight and children before puberty have their own ranges.
↓ What a low value means
According to MedlinePlus, a normal or low result makes the most common form of CAH (21-hydroxylase deficiency) less likely. If you still have symptoms, your doctor may order other tests to find the cause. During ongoing CAH treatment, a falling value over time is taken as a sign that the treatment is working.
↑ What a high value means
Elevated values can be related to congenital adrenal hyperplasia and, less often, to tumors of the adrenal gland. In adults, MedlinePlus lists values above 200 ng/dl (6.1 nmol/l) as a possible sign of the nonclassic, later-onset form. If the value lies between 200 and 800 ng/dl (6.1–24.2 nmol/l), an ACTH stimulation test may follow. A single elevated value is not a diagnosis; discuss any deviation with your doctor.
When to test
In many countries, 17-OHP is measured in newborn screening, most accurately more than 24 hours after birth. In teens and adults, the test is ordered for example when there is more facial and body hair than usual, irregular or absent periods, severe acne or infertility. No special preparation is usually needed; some medicines can affect the result. In women, the value depends on the cycle phase.
Frequently asked questions
Why is 17-hydroxyprogesterone measured when periods are irregular? +
Excess hair growth and irregular periods can have different causes, such as polycystic ovary syndrome (PCOS) or a nonclassic form of CAH. 17-OHP helps narrow down or rule out CAH as the cause. It is often measured together with testosterone and other hormones.
What is an ACTH stimulation test? +
17-OHP and cortisol are measured before and after an injection of ACTH. With CAH, 17-OHP rises sharply afterwards while cortisol barely changes. The test is used when a single 17-OHP value does not give a clear answer.
Is congenital adrenal hyperplasia inherited? +
Yes. CAH is caused by a change in the gene responsible for 21-hydroxylase; you inherit one copy of each gene from each parent. If CAH is known in your family, genetic counseling can clarify how likely it is to be passed on.
Do I need to prepare for the test? +
According to MedlinePlus, no special preparation is needed for a 17-OHP test. Because medicines can affect blood results, tell your doctor what you take and do not change anything without talking to them first.
17-Hydroxyprogesterone
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.