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Pregnenolone

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Formal name: Pregnenolone
Related tests: 17-Hydroxyprogesterone, Cortisol, ACTH, Aldosterone, Testosterone, Androstenedione, 11-Deoxycortisol, 17-Hydroxypregnenolone

At a Glance

Why Get Tested?

To help detect and monitor treatment for rare types of congenital adrenal hyperplasia (CAH); sometimes to help rule out other conditions

When to Get Tested?

When an infant has external sex organs that are not clearly male or female (ambiguous genitalia) and/or has high blood pressure (hypertension), low blood potassium (hypokalemia), or signs of excess loss of salt (salt wasting); when the most common cause for CAH, a 21-hydroxylase deficiency, has been ruled out; when a teen fails to develop secondary sexual characteristics and/or has delayed puberty

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

The Test Sample

What is being tested?

Pregnenolone is a chemical substance that is a precursor to all steroid hormones. This test measures the amount of pregnenolone in the blood in order to help detect rare forms of congenital adrenal hyperplasia (CAH).

CAH is a group of inherited disorders associated with deficiencies in the enzymes required for the production of the steroid hormones. CAH may be due to:

  • 21-hydroxylase deficiency, the most common cause of CAH (about 90% of cases)
  • 11-beta-hydroxylase deficiency (about 5-8% of cases)
  • 3-beta-hydroxysteroid dehydrogenase and 17-alpha-hydroxylase deficiencies, two rare forms of the disease

For normal steroid hormone production, cholesterol is converted into pregnenolone in the adrenal glands and then several enzymes complete the production of multiple hormones, including:

  • Cortisol, which helps metabolize proteins, lipids, and carbohydrates, maintain blood pressure, and regulate the immune system
  • Aldosterone, which maintains normal sodium and potassium levels in the blood and helps control blood volume and pressure
  • Sex steroid hormones – including androgens, the "male hormones" such as testosterone, and "female" hormones including estrogen and progesterone, which are responsible for the development and maintenance of male and female secondary sexual characteristics

In congenital adrenal hyperplasia, one or more of the enzymes is deficient or dysfunctional and inadequate amounts of one or more final products are produced. Because a low level of cortisol causes the level of a pituitary hormone that stimulates adrenal growth and hormone production (adrenocorticotropic hormone, or ACTH) to become elevated, the adrenal gland increases in size. However, the increased size and activity cannot overcome the block in cortisol production. Other substances (such as pregnenolone) that do not need the defective enzyme will be produced in excess.

With CAH, the enzyme deficiency can cause a decrease in cortisol and/or aldosterone and, in some cases, an increase or decrease in androgens. Deficient androgens can cause male newborns to be born with external sex organs that are not clearly male or female (ambiguous genitalia) and can affect the development of secondary sexual characteristics of both males and females at puberty.

Pregnenolone, several of the intermediate precursors, and one or more of the steroid hormones can be measured by laboratory tests to determine which enzyme is deficient or defective, based upon which products have been produced and how much.

If both 21- and 11-hydroxylase deficiencies have been ruled out (the most common forms of CAH), then analysis of pregnenolone, along with tests for other precursors, may be used to help establish a diagnosis of 3-beta-hydrosteroid dehydrogenase or 17-alpha-hydroxylase deficiency.

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

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Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

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(© 1995–2013). Pregnenolone, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/88645 through http://www.mayomedicallaboratories.com. Accessed June 2013.

Morley, J. (Revised 2013 February). Endocrine Disorders. Merck Manual for Healthcare Professionals [On-line information]. Available online through http://www.merckmanuals.com. Accessed June 2013.

Meikle, A. W. (2011 May). Adrenal Steroids Panel: High Specificity Lc-Ms/Ms Test For 11-Deoxycortisol, 17-Hydroxyprogesterone, 17-Hydroxypregnenolone, And Pregnenolone In Serum. ARUP Technical Information [On-line information]. Available online at http://www.aruplab.com/guides/ug/tests/iconpdf_25.pdf through http://www.aruplab.com. Accessed June 2013.

Meikle, A. W. (Updated 2013 January). Congenital Adrenal Hyperplasia – CAH. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/CAH.html?client_ID=LTD through http://www.arupconsult.com. Accessed June 2013.

Wilson, T. (Updated 2013 June 13). Congenital Adrenal Hyperplasia. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/919218-overview through http://emedicine.medscape.com. Accessed May 2013.

Frindik, J. P. (Updated 2012 May 30). 3-Beta-Hydroxysteroid Dehydrogenase Deficiency. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/920621-overview through http://emedicine.medscape.com. Accessed June 2013.

(Reviewed 2010 February). 3-beta-hydroxysteroid dehydrogenase deficiency. Genetics Home Reference [On-line information]. Available online at http://ghr.nlm.nih.gov/condition/3-beta-hydroxysteroid-dehydrogenase-deficiency through http://ghr.nlm.nih.gov. Accessed June 2013.

Miller, W. (2012 January). The Syndrome of 17,20 Lyase Deficiency. J Clin Endocrinol Metab v 97(1):59–67. [On-line information]. Available online at http://jcem.endojournals.org/content/97/1/59.full.pdf through http://jcem.endojournals.org. Accessed June 2013.

A.D.A.M. Health Solutions (Updated 2012 May 8). Congenital Adrenal Hyperplasia. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000411.htm. Accessed June 2013.

Scott, H. et. al. (2009 December 1). Steroidogenesis in the Fetal Testis and Its Susceptibility to Disruption by Exogenous Compounds. Endocrine Reviews v 30 (7) 883-925 [On-line information]. Available online at http://edrv.endojournals.org/content/30/7/883.full through http://edrv.endojournals.org. Accessed June 2013.

Kushnir, M. et. al. (2006 August) Development and Performance Evaluation of a Tandem Mass Spectrometry Assay for 4 Adrenal Steroids. Clinical Chemistry v 52 (8) 1559-1567 [On-line information]. Available online at http://www.clinchem.org/content/52/8/1559.full.pdf+html?sid=9d621d7c-9a8b-42c2-85f5-a0df3a464b7a through http://www.clinchem.org. Accessed June 2013.

Strushkevich, N. et. al. (2011 June 21). Structural basis for pregnenolone biosynthesis by the mitochondrial monooxygenase system. Proc Natl Acad Sci U S A. v 108 (25): 10139–10143. [On-line information]. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3121847/ through http://www.ncbi.nlm.nih.gov. Accessed June 2013.

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