17-Hydroxyprogesterone

This test measures the amount of 17-hydroxyprogesterone (17-OHP) in a sample of your blood. 17-OHP is a substance that your adrenal glands make. Your adrenal glands are two small organs that sit on top of each kidney. They make different types of hormones you need to stay alive and healthy.

Hormones are chemical messengers in your bloodstream that control the actions of certain cells or organs. Normally, your adrenal glands use 17-OHP to make a hormone called cortisol. Cortisol helps control your energy levels, blood glucose (sugar), blood pressure, and your body's response to stress, illness and injury.

A 17-OHP test helps diagnose a group of uncommon, inherited genetic disorders that affect how well your adrenal glands make cortisol. These genetic adrenal gland disorders are called congenital adrenal hyperplasia (CAH). People with CAH have a change in a gene that causes the lack of an enzyme that your adrenal glands need to make hormones.

The most common type of CAH is caused by a lack of an enzyme called 21-hydroxylase. 21-hydroxylase helps your adrenal glands use 17-OHP to make cortisol. Without enough 21-hydroxylase, the adrenal glands struggle to make enough cortisol. As the adrenal glands work harder to do their job, they become enlarged and make abnormally high levels of 17-OHP.

These high levels of 17-OHP are a sign of CAH with 21-hydroxylase deficiency. The adrenal glands use the extra 17-OHP to make larger than normal amounts of male sex hormones. This happens in children and adults of both sexes.

So, tests for male hormones, including testosterone, are often used with 17-OHP tests to help diagnose CAH. The symptoms of CAH depend on how much cortisol the adrenal glands are able to make. CAH is often organized into two groups based on how severe the symptoms are: Classic CAH includes the most severe forms of the disorder.

It's usually diagnosed at birth. Without diagnosis and treatment, severe CAH can be life-threatening. Serious symptoms may show up shortly after birth.

They may include: Dehydration; Low blood pressure; An irregular heartbeat (arrhythmia); Shock; Newborn girls with severe CAH may have external genitals that are not clearly female or male. This is caused by high levels of male hormones. In newborn boys, the genitals usually appear normal, but sometimes the penis may be larger than usual.

Classic CAH that is caused by a 21-hydroxylase deficiency can be diagnosed with 17-OHP testing. Less often, CAH is caused by a lack of a different enzyme. ; Nonclassic CAH includes mild forms of the disorder. It's also called late-onset CAH because symptoms show up between early childhood and early adulthood.

It is almost always caused by a lack of 21-hydroxylase and can be found with a 17-OHP test. Treatment is only needed if a person has symptoms. The symptoms depend on the person's age and sex.

For example: Children may have signs of early puberty, which means having signs of sexual development before age 8 in girls and before age 9 in boys.; Teenage girls and women may have more facial and body hair than usual and/or a deep voice.; Adults may have infertility.; ;

Why this test is done

Babies need a 17-OHP test as part of routine newborn screening tests to check for severe CAH:

• If you give birth in a hospital , your baby will usually have a 17-OHP test before going home. The test is most accurate when it's done more than 24 hours after birth. If your baby is tested sooner, ask your child's provider if a second test should be done at a later time. Some states require two tests for all babies.
• If you give birth at home, make sure your baby has all the necessary screening tests.

Symptoms of severe CAH usually begin within days or weeks after birth, but in certain cases, they may not show up until early childhood. These symptoms may be serious and include:

• Lack of energy
• Vomiting and other feeding problems
• Diarrhea
• Dehydration
• Failure to thrive (not gaining weight and growing as expected)

Children, teens, and adults may need testing if they develop symptoms of mild CAH (nonclassic CAH):

In children and teens, symptoms of mild CAH may include:

• Rapid growth that stops at a younger age than usual. As a result, older teens and adults with CAH may be shorter than average.
• Signs of early puberty.
• Severe acne, which may continue into adulthood.

In girls and women, symptoms of mild CAH may include:

• More facial and/or body hair than usual
• Irregular menstrual periods or no periods at all
• Thinning hair on the head, especially near the temples (male pattern baldness)
• Enlarged clitoris
• Infertility

In boys and men, symptoms of mild CAH may include:

• Enlarged penis with small testicles (testes)
• Low sperm count
• Infertility

How to prepare

There are no special preparations needed for a 17-OHP test.

Sample type

Blood

Other names for this test

17-OH progesterone, 17-OHP, 17 alphahydroxyprogesterone, 17 hydroxy progesterone: serum, progesterone: 17-hydroxy