Adrenocorticotropic Hormone

ACTH (Adrenocorticotropic Hormone) Test

How To Prepare

You may not be able to eat or drink for 10 to 12 hours before an ACTH test. Your doctor may ask you to eat low-carbohydrate foods for 48 hours before the test. Be sure to ask your doctor if there are any foods that you should not eat.

Many medicines can change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take. If you take a medicine, such as a corticosteroid, that could change the test results, you will need to stop taking it for up to 48 hours before the test. Your doctor will tell you exactly how long depending on what medicine you take.

Do not exercise for 12 hours before this test.

Try to avoid emotional stress for 12 hours before the test.

Collecting the blood sample at the right time is often important. Your blood will be drawn in the morning if your doctor wants a peak ACTH level. Your blood will be drawn in the evening if your doctor wants a low (trough) ACTH level.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

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Author:	Sydney Youngerman-Cole, RN, BSN, RNC	Last Updated: August 3, 2006
Medical Review:	Caroline S. Rhoads, MD - Internal Medicine David C.W. Lau, MD, PhD, FRCPC - Endocrinology & Metabolism
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