Children's Health

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Taking medicine, such as corticosteroids and medicines that act like cortisol or cause the release of cortisol, including amphetamines, lithium carbonate, and insulin.
• Being drunk (intoxicated).
• Being pregnant or having your period.
• Having a severe injury.
• Physical or emotional stress.
• Having a medical test that uses a radioactive tracer within 1 week before an ACTH test.

There are other medicines that may affect the test results, so talk with your doctor about any medicines you are taking.

What To Think About

• The interpretation of the ACTH test is complicated, because many things can change the results. Blood must be collected in special tubes, placed on ice, and processed quickly. The time of day when the blood is drawn can also change the results. ACTH test results should be compared to medical information gathered from other tests, especially the blood cortisol level. For more information, see the topic Cortisol in Blood.
• Inferior petrosal sinus sampling is a test that measures the amount of ACTH from a channel (inferior petrosal sinus) near the pituitary gland. This test may be done along with an ACTH blood test when the levels of both ACTH and cortisol are high. It is used to tell the difference between ACTH made by the pituitary gland and ACTH made somewhere else in the body. This test may only be available at large medical centers.