17-OHP is produced by the adrenal gland as part of the process of making the important hormone cortisol.

What are the adrenal glands?

These are two small glands. One is located on top of each kidney. Along with special enzymes, or proteins, 17-OH progesterone is converted to a hormone called cortisol.

Function of cortisol:

Cortisol is constantly released in varying amounts, but high levels are released during times of physical or emotional stress. Cortisol is also important in regulating metabolism and the immune system.

Cause and effect of Process interruption:

A cortisol deficiency can occur in people who lack the appropriate enzymes, which can lead to a buildup of 17-OH progesterone in the blood.

Several enzymes are required for this process. If a person is born with either not enough of one of these enzymes or an abnormal form of an enzyme, their adrenal gland cannot produce cortisol efficiently. Depending on which enzyme is abnormal, another important hormone, aldosterone may also be affected. In such cases, 17-OHP builds up. Some of the excess 17-OHP is used up by making male hormones (androgens). Excess androgens can cause the development of male sexual characteristics, in both females and young males.

These inherited enzyme deficiencies and the resulting excess androgens occur in a group of disorders called congenital adrenal hyperplasia (CAH).

More on CAH?

CAH can occur in both boys and girls. Young children with CAH may have ambiguous genitalia, pubic hair, or acne. The condition can also develop later in life in less obvious ways. Some common symptoms include clearly defined muscle tone, increased body hair, and a deeper voice.

In infants, CAH can sometimes cause dehydration or shock, both of which are very serious conditions. As a result, the 17-OH progesterone test should be part of every newborn’s initial medical examination.

Most cases of CAH are caused by a lack of the enzyme 21-hydroxylase. In more severe forms of CAH, the condition becomes evident in infancy or childhood, while milder forms, known as late-onset or non-classical CAH, may not become evident until later in life, including adulthood.

When to perform a 17-OH progesterone test? 

A doctor will usually order a 17-OH progesterone test for a young child, teenager, or adult who displays some of the classic symptoms of CAH. The sooner a person with CAH is diagnosed and treated, the less likely they are to experience complications.

Interpretation of the test results?

The results of a 17-OH progesterone test depend on many variables, including age, sex, and testing methods. This can make it difficult to identify normal and abnormal test results. Make sure to meet with the doctor to discuss what the 17-OH progesterone test results mean for you or your child.

In general, normal results for various age groups include:

• newborns: 1,000-3,000 nanograms/deciliter (ng/dL)
• babies older than 24 hours: less than 100 ng/dL
• adults: less than 200 ng/dL

References

• Fritz MA, Speroff L. Normal and abnormal sexual development. In: Speroff L, Fritz MA, eds. Clinical Gynecologic Endocrinology and Infertility. 8th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:chap 9.
• Lambert SM, Vilain EJ, Kolon TF. A practical approach to ambiguous genitalia in the newborn period. Urol Clin North Am. 2010; 37(2):195-205.
• Mark T. Endocrinology. In: Engorn B, Flerlage J, eds. Johns Hopkins: The Harriet Lane Handbook. 20th ed. Philadelphia, PA: Elsevier Mosby; 2015:chap 10.
• White PC. Congenital adrenal hyperplasia and related disorders. In: Kliegman RM, Bonita F, Stanton MD, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 576.