17-OH progesterone

Definition

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

Alternative Names

Why the Test is Performed

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 women who has excessive hair growth in places where adult men grow hair.

How the Test is Performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants and young children, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any bleeding.

The blood sample is sent to a laboratory for examination.

How to Prepare for the Test

Your doctor may tell you to stop taking any drugs that may cause fales 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.

How the Test Will Feel

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.

Risks

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)

Considerations

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

Normal Results

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.

What Abnormal Results Mean

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.