17-Hydroxyprogesterone Test

What is a 17-hydroxyprogesterone (17-OHP) test?

A 17-hydroxyprogesterone 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. Health care providers can use this test to help diagnose a group of uncommon genetic disorders that affect the adrenal glands. These genetic adrenal gland disorders are called congenital adrenal hyperplasia (CAH). Your adrenal glands are two small organs that sit on top of each kidney. They make different types of hormones, which 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. This hormone helps to control your energy levels, blood glucose (also called blood sugar), blood pressure, and your body's response to stress, illness, and injury. 

To use 17-OHP, your adrenal glands need an enzyme called 21-hydroxylase. An enzyme is a protein that speeds up certain chemical reactions in your body. Your body makes the 21-hydroxylase enzyme thanks to a specific gene. Genes are parts of DNA in your cells that you inherit from your parents. You inherit two copies of each gene, one from each parent. Genes carry information that controls what you look like and how your body works. 

A change in this gene causes CAH. Changes in your genes are also called gene variants or mutations. In the most common type of CAH, your body can't make enough 21-hydroxylase. This then makes your adrenal glands work harder to use 17-OHP to make cortisol. When your adrenal glands work harder, they become enlarged and make unhealthy levels of 17-OHP. 

Without 21-hydroxylase to help them use 17-OHP to make cortisol, 17-OHP levels go up. To get rid of this extra 17-OHP, your adrenal glands use it to make more male sex hormones than usual. 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.

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

What is it used for?

A 17-OHP test is used to help find and monitor the most common type of CAH, which is sometimes called 21-hydroxylase deficiency. This condition is often organized into two groups, based on how severe your symptoms are and at what age those symptoms show up.

• Classic CAH includes the most severe forms of the disorder and usually shows up at birth. Without diagnosis and treatment, classic CAH can be life-threatening.
• Nonclassic CAH includes mild forms of the disorder and usually show up between early childhood and early adulthood.

Your provider can use 17-OHP testing to:

• Check all newborns for severe (or classic) CAH. Newborn screening tests can't check for mild (or nonclassic) CAH. 
• Help diagnose nonclassic CAH in children, teens, and adults who have symptoms that could be caused by the disorder.
• Find out if treatment for CAH is working.
• Help rule out CAH in women who have certain symptoms such as large amounts of facial hair and irregular menstrual periods. These symptoms can also be caused by other conditions, such as polycystic ovarian syndrome (PCOS). 

Why do I need a 17-OHP test?

Babies need a 17-OHP test as part of routine newborn screening tests to check for classic 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 as soon as possible.

If your baby has classic CAH, they may start experiencing symptoms within days or weeks after birth. In certain cases, symptoms may not show up until early childhood. These symptoms may be serious and include:

• Lack of energy
• Low blood pressure
• An irregular heartbeat (arrhythmia)
• Vomiting and other feeding problems
• Diarrhea
• Dehydration
• Shock
• Faltering weight (not gaining weight and growing as expected)
• External genitals that are not clearly female or male (especially in newborn girls)

Children, teens, and adults may need testing if they develop symptoms of nonclassic CAH. These symptoms can vary depending on your age and sex.

In children and teens, symptoms 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, which means having signs of sexual development before age 8 in girls and before age 9 in boys.
• Severe acne, which may continue into adulthood.

In girls and women, symptoms 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 may include:

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

What happens during a 17-OHP test?

For a newborn screening, a health care professional will clean your baby's heel with alcohol. Then the provider will stick the baby 's heel with a small needle to collect a few drops of blood. The heel will then be bandaged.

For older children and adults, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

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

Are there any risks to the test?

There is very little risk from a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. Your baby may feel a little pinch when the heel is poked. A small bruise may form on the heel, but it should go away quickly.

What do the results mean?

The results of a 17-OHP test help show whether you or your child have the most common type of CAH (21-hydroxylase deficiency).

If test results show a normal amount of 17-OHP, it means that you or your child probably do not have CAH with 21-hydroxylase deficiency. If you or your child has symptoms, your provider may order other tests to figure out the cause.

If test results show higher than normal levels of 17-OHP, you or your child probably has CAH. Your provider may order other tests to learn more about how CAH is affecting you or your child. If your newborn's 17-OHP levels are only slightly elevated, it may not necessarily mean your baby has CAH. Your provider will likely perform other tests to confirm or rule out this diagnosis. 

If you or your child is being treated for CAH, decreasing levels of 17-OHP over time means that the treatment is working. Treatment for CAH is usually only recommended if you or your child has symptoms. These treatments may include medicines to replace the cortisol your body can't make. Other medicines may also be needed, depending on the type of CAH. If a girl is born with atypical external genitals, surgery may also be done. 

If you, your child, or another family member has been diagnosed with CAH, you may want to talk with a genetic counselor. Genetic counselors are trained in genetics and genetic testing. They can help you learn how likely you are to pass CAH to future children.  

If you have questions about the results of a 17-OHP test, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results. 

Is there anything else I need to know about a 17-OHP test?

If the results of your 17-OHP test aren't clear, your provider may order another test to measure your 17-OHP. This is called an ACTH stimulation test. It involves measuring your cortisol and 17-OHP levels before and after you have an injection (shot) of ACTH (adrenocorticotropic hormone).

ACTH is a hormone your body makes to trigger your adrenal glands to make cortisol. If you have CAH, the ACTH injection will make your 17-OHP levels increase a lot, but it will not increase your cortisol levels.