Living with congenital adrenal hyperplasia (CAH) often means getting regular lab tests. These tests usually involve giving a blood or urine sample that’s examined in a lab. The results help your endocrinologist make sure your treatment is working as it should.

Monitoring for CAH needs to continue throughout your life. If you or your child is moving from pediatric to adult care or changing medication doses, testing may be needed every three to four months until your treatment plan is stable. Many adults with CAH get tested at least once a year. Here’s what to know about the most common tests for monitoring CAH.

Why Is the Timing of Lab Tests Important?

Your endocrinology team may give you specific times of day to have testing done. That’s because the levels of hormones related to your adrenal gland naturally rise and fall throughout the day. Cortisol and androgens are usually highest in the morning and lower later in the day.

Your medications can also affect hormone levels. Glucocorticoids, a standard treatment for classic CAH, can change your test results. Your healthcare provider may ask you to get tested at a certain time before or after taking your medication to help them read the results correctly.

If you’ve recently been sick, had a lot of stress, or taken stress (extra) doses of glucocorticoids, tell your doctor. These situations might affect your hormone levels. Even the stress of getting lab work can sometimes change your test results.

Common Tests To Monitor CAH Treatment

Here are some of the most common lab tests your doctor may order to monitor CAH. Unless otherwise noted, these tests are typically used to monitor classic CAH. Some may also be helpful for tracking nonclassic CAH or other forms of CAH, depending on how the condition affects you and what your doctor needs to monitor over time.

1. 24-Hour Urine Collection

Collecting urine over 24 hours is helpful for understanding how your hormones are working in classic CAH. This test focuses on androgen production, but it’s not used as often today.

For this test, your doctor or the lab will give you a container in which you’ll collect urine over the course of an entire day. You’ll start by urinating into a toilet as usual in the morning, then collect all your urine into the container for the next 24 hours, including the first urine the next morning. You should store the container in a cool, dry place while you’re collecting, and return it to the lab when finished.

Collecting urine over 24 hours is helpful for understanding how your hormones are working in classic CAH.

The lab will measure levels of 17-ketosteroids and pregnanetriol in your urine sample. These two substances are made when your body breaks down hormones like androstenedione, testosterone, and 17-hydroxyprogesterone (17-OHP). The results help your doctor understand how much of these hormones your body is making and whether you have signs of androgen excess. Your levels are compared to a standard range to help guide medication adjustments.

Your endocrinologist will decide how often you need 24-hour urine testing. This test gives the most comprehensive results, but it’s not very convenient — especially for kids or teens. Some doctors may recommend it regularly, some have it done just once in a while, and others skip it entirely and do blood tests instead.

2. 17-Hydroxyprogesterone

A 17-OHP test measures the amount of 17-hydroxyprogesterone in your blood at the time of testing. Your adrenal glands use 17-OHP as a building block to make cortisol — an essential hormone that plays a role in managing energy levels, blood sugar, and more.

In the most common type of CAH, the body can’t make enough of an enzyme called 21-hydroxylase, which is needed to turn 17-OHP into cortisol. When this enzyme is missing or not working well, 17-OHP builds up in the body. The adrenal glands then use the extra 17-OHP to make androgens (male sex hormones).

Checking 17-OHP levels helps your doctor see whether your CAH medications are working as intended. This test is done with a blood sample. If your doctor needs to monitor your 17-OHP levels closely, you may have to give a blood sample every three or four months. Other times, the test may be needed only yearly. Your doctor may use this test along with others because 17-OHP can fluctuate even when treatment is on track.

If your doctor needs to monitor your 17-OHP levels closely, you may have to give a blood sample every three or four months. Other times, it may be once a year.

3. Androstenedione

Androstenedione, or A4, is another hormone that can be measured with a blood test. Similar to 17-OHP, when 21-hydroxylase is missing or not working well, A4 builds up in the body, which leads to too many androgens. Blood samples for A4 are often taken at the same time as tests for 17-OHP and other hormones.

A4 is a biomarker for checking adrenal function in people with CAH. Some researchers believe A4 is among the more useful hormones to track when adjusting treatment.

Like other adrenal hormones, A4 levels are usually higher in the morning. If your levels are high later in the day, it may mean you’re not getting enough treatment. Your doctor may give you careful instructions about how to time this test.

4. Testosterone

Testosterone levels are also measured with a blood test. When you get routine blood work for CAH, your doctor will likely include testosterone among the hormones to check. Like androstenedione, testosterone can help show how well your treatment is working.

However, testosterone testing may be less useful in adolescent or adult males than in other people, according to the CARES Foundation. Testosterone levels naturally rise during puberty in males, making it harder to tell if elevated levels are from CAH or part of normal development.

5. Adrenocorticotropic Hormone

Some endocrinologists include adrenocorticotropic hormone (ACTH) in routine CAH testing. ACTH is made by the pituitary gland and plays a key role in helping the adrenal glands produce cortisol.

ACTH testing isn’t always reliable, so doctors often combine it with other tests. However, when you’re not getting enough treatment, levels are higher than normal about 75 percent of the time. Your doctor may use ACTH results along with others to make sure your medications are effective.

6. Plasma Renin Activity or Direct Renin (With Serum Electrolytes)

If you have salt-wasting classic CAH, your body may not be able to keep the right amount of salt in your blood due to low levels of a hormone called aldosterone. When aldosterone is low, your body releases renin, a hormone that helps control blood pressure and is related to hormones made by the adrenal glands.

If CAH affects your salt levels, your doctor will check your renin levels during regular blood tests. They’ll also measure your electrolytes. Together, these results will help your doctor decide if your medication or salt intake needs to change. Generally, high renin levels mean that you need more medication and/or salt, and low levels mean you’re getting too much.

If you have salt-wasting classic CAH, your doctor may order tests to check your levels of renin, which helps control blood pressure.

Join the Conversation

On CAHteam, people share their experiences with congenital adrenal hyperplasia, get advice, and find support from others who understand.

What lab tests does your endocrinologist order to manage care for CAH? Let others know in the comments below.