A low-dose ACTH stimulation test measures how well the adrenal glands respond to a hormone called ACTH (adrenocorticotropic hormone). During the test, your child gets a low dose of a medicine called cosyntropin. This medicine works like ACTH and signals the adrenal glands to release cortisol.
This test helps your child's care team check how well the hypothalamic-pituitary-adrenal (HPA) axis is working. The HPA axis includes the hypothalamus, pituitary gland, and adrenal glands. These structures work together to control how the body makes cortisol.
Cortisol is a hormone that helps the body respond to stress, illness, and injury. It helps control blood pressure, immune responses, and blood sugar levels.
A low-dose ACTH stimulation test can help diagnose conditions such as central adrenal insufficiency (CAI). Children who have had a brain tumor or were treated with chemotherapy, radiation therapy, or long-term steroid treatment may develop CAI as part of endocrine late effects.
A low-dose ACTH stimulation test measures how well the adrenal glands respond to ACTH and make the hormone cortisol. This test can help diagnose problems such as central adrenal insufficiency.
How to prepare for the test
Your care team will give you information on how to prepare for the test and what to expect. Always follow their instructions. In most cases:
Your child can eat and drink as usual before the test.
Give your child their usual medicines unless your care team tells you otherwise.
Dress your child in comfortable clothes.
Bring activities that will keep them busy during the test, such as books, games, or tablets.
What to expect during the test
Your care team will explain what to expect. In general:
You can stay with your child during the test.
Before the test, your care team will place an IV in your child’s arm to use for blood samples. They may numb the skin before placing the IV.
Your child will get cosyntropin through their IV.
During the test, the care team will draw blood samples from the IV at scheduled times.
A nurse will monitor your child during the test and remove the IV when the test is done.
The test usually takes about 1 hour.
Possible risks or side effects of the test
The test is generally safe, and any side effects are usually mild and improve soon after the test. Side effects from the test are rare.
Possible side effects include:
Feeling dizzy or lightheaded
Pain or discomfort from the needle stick
Mild bleeding or bruising at the IV site
Temporary flushing (redness of the skin)
After the test
Your child can return to normal activities after the test.
Blood samples are sent to the lab for testing. Your care team will share the test results with you and tell you what they mean.
What do the test results mean?
The low-dose ACTH stimulation test results will show how well your child’s adrenal glands respond to ACTH to make cortisol. Your child’s results may show one of the following:
Normal response: The adrenal glands are functioning normally and making cortisol as expected.
Abnormal response: The adrenal glands are not making cortisol as expected, which may suggest adrenal insufficiency.
Questions to ask your care team
Why does my child need a low-dose ACTH stimulation test?
How should my child prepare for the test?
Can my child take their usual medicines before the test?
How long does the test take?
What does the test feel like?
Are there any risks or side effects from the test?
How and when will we get the test results?
What is a normal cortisol level after an ACTH stimulation test?
What happens if my child’s cortisol levels are low?
Will my child need other tests?
Key points about a low-dose ACTH stimulation test
A low-dose ACTH stimulation test measures how well the adrenal glands respond to the hormone ACTH.
During the test, your child will get the medicine cosyntropin, a man-made form of ACTH.
Blood samples will be taken to measure the levels of cortisol over time.
A low-dose ACTH test helps diagnose central adrenal insufficiency and check how well the HPA axis is working.
Most children do not have any side effects from the test and can return to usual activities the same day.
A standard dose ACTH (cosyntropin) stimulation test measures adrenal gland function and helps diagnose adrenal insufficiency. Learn what to expect from this test.
