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Pregnenolone
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Hormones · Blood
17-hydroxypregnenolone
An intermediate step in making adrenal hormones; mainly meaningful when testing for a rare inherited enzyme disorder.
At a glance
- Measured in blood
- In 1 test panel
- Check the preparation
Explanation
17-hydroxypregnenolone: what is measured?
17-hydroxypregnenolone is made from pregnenolone in the adrenal glands and the sex glands. It is an intermediate step on the way to DHEA and, via 17-hydroxyprogesterone, to cortisol. If the enzyme that converts 17-hydroxypregnenolone further (3-beta-hydroxysteroid dehydrogenase) does not work properly, the substance builds up. The value follows the daily rhythm of the adrenal gland and rises sharply after ACTH is given, the hormone from the pituitary gland that stimulates the adrenal gland.
What can it detect?
- A sign of a deficiency of the adrenal enzyme 3-beta-hydroxysteroid dehydrogenase, a rare form of congenital adrenal hyperplasia (CAH)
- Distinguishing between different forms of CAH, together with 17-hydroxyprogesterone and other adrenal hormones
Result
What does the result mean?
17-hydroxypregnenolone too high
A slightly raised value is often caused by a sample taken early in the morning, stress or illness, or by using pregnenolone or DHEA supplements. In newborns and during puberty, values are naturally higher. A clearly raised value, especially after an ACTH stimulation test and in relation to 17-hydroxyprogesterone, may fit a deficiency of the enzyme 3-beta-hydroxysteroid dehydrogenase. In children, this can cause abnormal development of the genitals and salt loss; in women with a mild form, symptoms include excess hair growth and irregular periods.
17-hydroxypregnenolone too low
A low value is often caused by a sample taken later in the day or by using corticosteroids, which suppress the body's own production. When the adrenal glands or the pituitary gland work less well, the value is also low, but then mainly cortisol is abnormal. A low value without symptoms says little.
After an abnormal result
With an abnormal value and matching symptoms, the GP usually first has 17-hydroxyprogesterone, DHEA-S and testosterone measured. If CAH is suspected, referral follows to an endocrinologist (internist specializing in hormones) or pediatrician for an ACTH stimulation test. An abnormal value without symptoms usually does not lead to further testing.
Reliability
How reliable is the test?
A single 17-hydroxypregnenolone value has limited predictive value. When CAH is suspected, an abnormal 17-hydroxyprogesterone says more; 17-hydroxypregnenolone is an addition to it. For a mild form of the enzyme deficiency, the result can only be interpreted properly after an ACTH stimulation test and in relation to other adrenal hormones, and the cut-off values for this are not fixed. A slightly abnormal value without an ACTH test is common without there being a disorder. The test is not supported as a measure of 'hormone balance'.
What can affect the result?
- Timing: the value is highest early in the morning; a single value without an ACTH test is hard to interpret.
- Reference values depend strongly on age; in newborns and during puberty, values are higher.
- Immunoassays can react with related steroids; a measurement with mass spectrometry is more accurate, and results differ between laboratories.
- Corticosteroids lower the value; pregnenolone and DHEA supplements raise it.
Preparation
- Have your blood taken in the morning, because the value falls during the day.
Who it is for
Who is the test useful for?
Useful for
The result is most meaningful for a targeted question about an inherited disorder in the production of adrenal hormones, for example with excess hair growth and a raised DHEA-S or with known CAH in the family, together with 17-hydroxyprogesterone and after an ACTH test. Not suitable as a measure of 'hormone balance', stress or tiredness. In people without symptoms, a single value says little.
How common is it?
The severe, inherited form of CAH is diagnosed in 12 to 15 children a year in the Netherlands, usually through the newborn heel prick screening; by far most cases are caused by a different enzyme deficiency (21-hydroxylase). A deficiency of 3-beta-hydroxysteroid dehydrogenase is very rare.
Maastricht UMC+, Department of Endocrinology
Drawbacks and risks
- A slightly raised value without an ACTH test and without symptoms can lead to unnecessary worry about an inherited adrenal disorder and to unnecessary follow-up testing.
Get tested
17-hydroxypregnenolone: test panels
17-hydroxypregnenolone is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.
Evidence
Sources
This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.
More about risks and results