What is a 17-hydroxyprogesterone (17-OHP) test?
This test measures the amount of 17-hydroxyprogesterone (17-OHP) in the blood. 17-OHP is a hormone made by the adrenal glands, two glands located on top of the kidneys. The adrenal glands make several hormones, including cortisol. Cortisol is important for maintaining blood pressure, blood sugar, and some functions of the immune system. 17-OHP is made as part of the process of producing cortisol.
A 17-OHP test helps diagnose a rare genetic disorder called congenital adrenal hyperplasia (CAH). In CAH, a genetic change, known as a mutation, prevents the adrenal gland from making enough cortisol. As the adrenal glands work harder to make more cortisol, they produce extra 17-OHP, along with certain male sex hormones.
CAH can cause abnormal development of sex organs and sexual characteristics. Symptoms of the disorder range from mild to severe. If not treated, the more severe forms of CAH can cause serious complications, including dehydration, low blood pressure, and abnormal heartbeat (arrhythmia).
Other names: 17-OH progesterone, 17-OHP
What is it used for?
A 17-OHP test is most often used to diagnose CAH in newborns. It may also be used to:
- Diagnose CAH in older children and adults who may have a milder form of the disorder. In milder CAH, symptoms may show up later in life, or sometimes not at all.
- Monitor treatment for CAH
Why do I need a 17-OHP test?
Your baby will need a 17-OHP test, usually within 1–2 days after birth. 17-OHP testing for CAH is now required by law as part of newborn screening. A newborn screening is a simple blood test that checks for a variety of serious diseases.
Older children and adults may also need testing if they have symptoms of CAH. Symptoms will be different depending on how severe the disorder is, the age when symptoms appear, and whether you are male or female.
Symptoms of the most severe form of the disorder usually show up within 2–3 weeks after birth.
If your baby was born outside the United States and did not get a newborn screening, they may need testing if they have one or more of the following symptoms:
- Genitals that are not clearly male or female (ambiguous genitalia)
- Vomiting and other feeding problems
- Abnormal heart rhythms (arrhythmia)
Older children may not have symptoms until puberty. In girls, symptoms of CAH include:
- Irregular menstrual periods, or no periods at all
- Early appearance of pubic and/or arm hair
- Excessive hair on face and body
- Deep voice
- Enlarged clitoris
In boys, symptoms include:
- Enlarged penis
- Early puberty (precocious puberty)
In adult men and women, symptoms may include:
What happens during a 17-OHP test?
For a newborn screening, a health care professional will clean your baby's heel with alcohol and poke the heel with a small needle. The provider will collect a few drops of blood and put a bandage on the site.
During a blood test 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 to you or your baby with a 17-OHP 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, and a small bruise may form at the site. This should go away quickly.
What do the results mean?
If results show high levels of 17-OHP, it's likely you or your child has CAH. Usually, very high levels means a more severe form of the condition, while moderately high levels usually means a milder form.
If you or your child is being treated for CAH, lower levels of 17-OHP may mean the treatment is working. Treatment may include medicines to replace missing cortisol. Sometimes surgery is done to change the appearance and function of the genitals.
If you have questions about your results or your child's results, talk to your health care provider.
Is there anything else I need to know about a 17-OHP test?
If you or your child has been diagnosed with CAH, you may want to consult with a genetic counselor, a specially trained professional in genetics. CAH is genetic disorder in which both parents must have the genetic mutation that causes CAH. A parent may be a carrier of the gene, which means they have the gene but usually don't have symptoms of disease. If both parents are carriers, each child has a 25% chance of having the condition.
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