What is the role of adrenocorticotropic hormone (ACTH) stimulation test in the diagnosis of hypopituitarism (panhypopituitarism)?

Updated: Jun 09, 2020
  • Author: Bernard Corenblum, MD, FRCPC; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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The ACTH stimulation test, which evaluates the hypothalamic-pituitary-adrenal axis, is a superior tool in the diagnosis of adrenal insufficiency, but it does not generally separate pituitary from adrenal causation. This dynamic test measures serum cortisol levels before and after a 1- or 250-mcg dose of ACTH. The cortisol level should be greater than 500 pmol/L (may be  less in some assays) 30 minutes after ACTH administration in patients with normal adrenal function.

A low cortisol level that fails to rise after ACTH administration represents an abnormal cortisol response, a response seen in primary adrenal insufficiency. However, because of adrenal atrophy with chronic ACTH insufficiency, the cortisol response is often abnormal in patients with hypopituitarism. A poor response requires the serum ACTH, or other clinical clues, to separate pituitary from primary adrenal disease.

Other provocative tests for ACTH/cortisol function are the insulin-induced hypoglycemia test and the glucagon stimulation test. These may be needed within the acute stage of ACTH deficiency, such as following pituitary surgery.

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