Synacthen This test is a way to check if the adrenal glands are working properly. Synacthen can be used to rule out the presence of an adrenal gland disorder, also known as Addison's disease. The test consists of an injection of a synthetic peptide that stimulates the secretion of steroids from the adrenal cortex. This injection is expected to stimulate the adrenal glands to secrete their hormones, including cortisol. The level of this hormone can be measured in the blood. If there is a problem with the adrenal glands themselves, the level of cortisol in the blood may not rise or rise only slightly.