17-OH progesterone is a blood test that measures the amount of 17-OH progesterone, a hormone produced by the adrenal glands and gonads.

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

The blood sample is sent to a laboratory for examination.

Your doctor may tell you to stop taking any drugs that may cause false test results. Such drugs include corticosteroids and birth control pills.

Your doctor may also recommend that the test be done at a specific time of day, since it is sensitive to circadian rhythms, the natural highs and lows that the body experiences during a 24-hour period.

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may some throbbing.

This test is mainly used to check infants for congenital adrenal hyperplasia (CAH). It is often performed on infants who are born with outer genitals that do not have the typical appearance of a boy or a girl.

This test is also used to identify persons with nonclassical adrenal hyperplasia. This condition occurs when the body does not product enough of a substance that helps the adrenal gland make cortisol.

Your doctor may recommend this test if you are a woman who has excessive hair growth in places where adult men grow hair, or if you have other signs of virilization.

Normal and abnormal values differ for babies born with low birth weight. In general, normal results are as follows:

• Cord blood - 1,000 - 3,000 ng/dL
• >24 hours - less than 100 ng/dL
• Adults - less than 200 ng/dL

Note: ng/dL = nanograms per deciliter.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

High levels of 17-OH progesterone may be due to:

• Adrenal tumors
• Congenital adrenal hyperplasia (CAH)

In infants with CAH, 17-OHP levels range from 3,000 - 40,000 ng/dL. In adults, a level greater than 200ng/dL may be due to nonclassical adrenal hyperplasia.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks may include:

• Excessive bleeding
• Fainting or feeling lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Your doctor may suggest an ACTH test if your 17-OH progesterone level is between 200 - 800 ng/dL.

Speroff L, Fritz MA, eds. Normal and Abnormal Sexual Development in Clinical Gynecologic Endocrinology & Infertility. Baltimore, Md: Williams & Wilkins; 2005.