ACTH Stimulation Test (ACTH) – Why am I having this test?
Adrenocorticotropic hormone stimulation test indirectly shows how well your adrenal glands are working. ACTH is a hormone that is produced by a gland in your brain called the pituitary gland.
ACTH stimulates your two adrenal glands, which are located above each kidney. The adrenal glands produce hormones that are released into the blood. One of these hormones is cortisol. Cortisol helps your body to respond to stress.
If your adrenal glands are not responding to ACTH properly, you may have too much or too little cortisol.
What kind of sample is taken?
Two or more blood samples are required for this test. Blood samples are usually collected by inserting a needle into a vein. Cortisol will be measured in the first blood sample to provide a baseline level.
After the first blood sample has been collected, you will be given cosyntropin. Cosyntropin is similar to ACTH and should cause the adrenal glands to release cortisol. Cosyntropin is usually given through an IV tube. It could also be given as an intramuscular (IM) injection. At specified intervals after receiving the cosyntropin, you will have one or more blood samples taken to measure your cortisol levels. The test results will be compared to show the amount of cortisol in your blood before and after you were given cosyntropin.
How do I prepare for this test?
Do noteat or drink anything after midnight on the night before the test or as directed by your health care provider.
What are the reference values?
Reference values are considered healthy values established after testing a large group of healthy people. Reference values may vary among different people, labs, and hospitals. It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.
The following are reference values for the various ACTH stimulation tests:
- Rapid test: cortisol levels increase greater than 7 mg/dL above baseline.
- 24-hour test: cortisol levels greater than 40 mcg/dL.
- 3-day test: cortisol levels greater than 40 mcg/dL.
What do the results mean?
Results outside of the reference value may indicate:
- Cushing syndrome.
- Adrenal insufficiency.
Talk with your health care provider to discuss your results, treatment options, and if necessary, the need for more tests. Talk with your health care provider if you have any questions about your results.
Talk with your health care provider to discuss your results, treatment options, and if necessary, the need for more tests. Talk with your health care provider if you have any questions about your results.
