If you or your child is experiencing symptoms of congenital adrenal hyperplasia (CAH), it’s important to talk with a doctor. They can run tests to check hormone levels and look for genetic mutations (changes).

This article will cover seven tests for CAH, how they work, and what they tell your doctor. For more information about how doctors diagnose CAH, talk to your endocrinologist (hormone specialist) or a genetic counselor.

When Do Doctors Test for CAH?

Your doctor might want to run tests for CAH for several reasons. Some people have high levels of the sex hormone androgen, along with other CAH symptoms. Other people might have a child or another family member who was recently diagnosed with CAH. Doctors or genetic counselors can offer testing to see if you’re at risk of passing this condition to your children.

CAH affects the adrenal glands — tiny organs that play a major part in controlling your body’s hormone balance. The adrenal glands sit on top of your kidneys and release aldosterone, cortisol, and androgens. People with CAH don’t make enough of an enzyme called 21-hydroxylase, a specialized protein that’s needed to make the adrenal hormones.

If you or your child is experiencing symptoms of CAH, your doctor can do several tests to make a diagnosis. It’s important to start and stick with your treatment plan after you’re diagnosed to avoid health complications.

1. Genetic Testing

Genetic testing takes a close look at your DNA to find genetic mutations. People with CAH have changes in the CYP21A2 gene, which provides instructions for making 21-hydroxylase. A health care provider takes a small blood sample to perform genetic testing. The sample is sent to a lab to check for specific CYP21A2 changes.

You may undergo genetic testing if you have symptoms of CAH and have been experiencing infertility. Your doctor can also recommend this testing if you have abnormally high androgen levels. People who have family members with CAH can also get tested to find out if they carry a mutated CYP21A gene. This information can help you plan for future pregnancies.

2. Prenatal Testing for CAH

CAH is a genetic condition passed down from parents to their children. Everyone inherits two sets of chromosomes — one from their mother and the other from their father. To develop CAH, you need to inherit two nonworking copies of the CYP21A2 gene.

Doctors or genetic counselors may recommend prenatal testing if:

• You already have one child who has CAH.
• You or your partner is a known carrier of the CYP21A2 gene (has one mutated copy).
• You or your partner has CAH (two mutated copies).

If any of these statements apply to you, you have a higher chance of passing CAH along to your child. Doctors can do prenatal testing to check if the fetus has CAH. There are two options for these tests — chorionic villus sampling and amniocentesis.

For chorionic villus sampling, your doctor inserts a needle into the womb through the cervix or abdomen and then guides the needle to the chorionic villi. These projections of tissue eventually become the placenta that supports the growing fetus. A small piece of tissue is removed and tested for gene changes. This test must be performed in the 10th to 12th week of pregnancy.

During amniocentesis, a needle inserted into the abdomen takes a sample of amniotic fluid surrounding the fetus. The fluid is sent to a lab for genetic testing. Doctors typically perform this test in the first 15 to 20 weeks of pregnancy.

If prenatal testing shows that your baby has CAH, your doctor may recommend taking dexamethasone. This corticosteroid — a lab-made hormone drug — is used to treat CAH.

3. Newborn Screening Test

All 50 states in the United States offer newborn screening for CAH. Shortly after your baby is born, a health care professional takes a small blood sample from your baby’s heel. The sample is sent to a lab to measure levels of 17-hydroxyprogesterone (17-OHP).

Your baby’s 17-OHP levels may be high if they’re not making enough of the hormone cortisol. People with CAH have more 17-OHP in their blood because they’re missing the enzyme 21-hydroxylase.

If the results show high 17-OHP levels, your baby will need more testing to confirm CAH and rule out other conditions. It’s important to note that newborn screening tests can only diagnose classic CAH. Infants with nonclassic CAH are typically diagnosed as children or adults. The sections below discuss these tests.

4. Physical Exam

Doctors use physical exams to look at your appearance for signs of certain health conditions. CAH causes elevated androgen levels, and people with the condition tend to have specific sets of symptoms that point to a diagnosis. Symptoms depend on the type of CAH you have.

According to Cleveland Clinic, a female infant with classic CAH may have ambiguous genitalia, with outer organs that may look more similar to a penis and testicles than a vulva and clitoris, but may still have internal organs like ovaries. A male infant with CAH may have an enlarged penis.

Children and teenagers with classic CAH will also have specific symptoms. Many experience early puberty, developing facial, armpit, and pubic hair sooner than normal. According to Cleveland Clinic, females can develop certain characteristics associated with males, like a deep voice or larger muscles.

Nonclassic CAH is milder than classic CAH, and the symptoms may look different in a physical exam. Nonclassic CAH tends to cause:

• Early signs of puberty
• Acne
• Male-pattern baldness
• Extra body hair and facial growth
• Small testicles and an enlarged penis

5. Urine Test

The hormone aldosterone is key to maintaining your body’s fluid and electrolyte (mineral) balance. People with CAH can get rid of too much sodium (salt) in their urine. They also get rid of less potassium than normal. This is why you may hear some types of CAH referred to as “salt wasting.” Your doctor can run a quick urine test to measure how much sodium and potassium your kidneys are getting rid of.

6. X-Rays for Bone Age

Children’s bodies are constantly growing. During puberty, growth plates at the ends of long bones in the arms and legs turn into solid bone tissue. When growth plates close, a person is done growing.

Children with CAH grow much faster than those who don’t have the condition. Your child’s doctor may take X-rays of the pelvis, wrists, and hands to check whether their growth plates have closed early. These bone age studies also help monitor your child’s growth and how effective their CAH treatment plan is over time.

7. Adrenocorticotropic Hormone Stimulation Test

Another test doctors use to diagnose CAH is known as the adrenocorticotropic hormone (ACTH) stimulation test. ACTH tells your adrenal glands to release cortisol.

The health care provider running the test will take a blood sample to measure your baseline hormone levels. You’ll then get an injection of ACTH to stimulate your adrenal glands, and the provider will take another blood sample to see if the injected ACTH prompted changes in your androgen and 17-OHP levels.

During ACTH stimulation, people with classic CAH will have very high levels of 17-OHP and androgens. Levels for people with nonclassic CAH also will be elevated but not as much.

Talk With Others Who Understand

On CAHteam, the site for people with congenital adrenal hyperplasia and their loved ones, people come together to gain a new understanding of CAH and share their stories with others who understand life with the condition.

Are you or a loved one living with CAH? What tests helped make a diagnosis? Share your experience in the comments below.