When your body doesn’t make enough ACTH, a hormone made by the pituitary gland that tells your adrenal glands to produce cortisol. Also known as adrenocorticotropic hormone, it’s the key signal that keeps your stress response working. If this signal is weak or missing, your body can’t handle physical stress — leading to fatigue, low blood pressure, and even life-threatening crashes. The ACTH stimulation test, a simple blood test that measures how well your adrenal glands respond to synthetic ACTH is the most direct way to find out if the problem is in your adrenals or your pituitary.
Doctors use this test when they suspect adrenal insufficiency, a condition where your adrenal glands don’t produce enough cortisol and sometimes aldosterone. It’s not just for Addison’s disease — it’s also used to check for secondary adrenal failure caused by long-term steroid use, pituitary tumors, or even after brain surgery. The test works by giving you a shot of synthetic ACTH, then checking your cortisol levels, the main stress hormone your adrenals release in response before and 30 to 60 minutes later. If your cortisol doesn’t rise enough, your adrenals aren’t responding — meaning the issue is likely in the glands themselves. If cortisol is low but rises normally after the shot, the problem is probably upstream — your pituitary isn’t making enough ACTH.
What you’ll find in the posts below is a mix of real-world cases, lab interpretations, and related hormone tests that help paint the full picture. You’ll see how the ACTH stimulation test connects to other diagnostics like the insulin tolerance test or CRH stimulation test, and how results can be confused by medications, pregnancy, or even chronic illness. Some posts dive into how adrenal function affects everything from blood pressure to energy levels, while others explain why some patients get misdiagnosed for years before this test is even considered. There’s no fluff here — just clear, practical info on how this test works, what it rules out, and what comes next if the results aren’t normal.
Long-term steroid use suppresses natural cortisol production. ACTH stimulation testing is the gold standard to safely guide tapering and prevent adrenal crisis. Learn how testing works, when to do it, and what the results mean.
