When your body can’t handle stress the way it should, the ACTH stimulation test, a diagnostic procedure that measures how well your adrenal glands respond to the hormone ACTH. Also known as the cosyntropin test, it helps doctors figure out if your adrenal glands are producing enough cortisol — the key hormone that keeps you going when you’re sick, stressed, or exhausted. This isn’t just a routine check. It’s often the first step when someone has unexplained fatigue, low blood pressure, or sudden weight loss — signs that your body’s stress system might be broken.
The test works by giving you a small shot of synthetic ACTH, then measuring your cortisol levels before and after. If your adrenal glands don’t react, it could mean they’re damaged — a condition called adrenal insufficiency, a disorder where the adrenal glands don’t make enough cortisol and sometimes aldosterone. If your pituitary gland isn’t sending the right signals, that’s another issue — secondary adrenal insufficiency, caused by low ACTH production from the pituitary. And if your cortisol spikes too high? That might point to Cushing’s or a tumor. These aren’t just medical terms — they’re real conditions that change how you feel every day.
People get this test after unexplained symptoms, after long-term steroid use, or when other blood tests come back weird. It’s simple, quick, and usually done in a clinic. You don’t need to fast, but you might be asked to skip certain meds. The whole thing takes about an hour. No needles in your spine, no scans — just two blood draws. And yet, it can tell you more about why you’re always tired than months of guesswork.
Below, you’ll find real-life guides and comparisons that connect to this test — from how adrenal problems affect your immune system, to what happens when thyroid and cortisol levels clash, to how stress triggers physical breakdowns like hair loss or chronic pain. These aren’t theory pages. They’re practical, tested insights from people who’ve been there. Whether you’re trying to understand your own test results or helping someone else, you’ll find answers that actually make sense.
Learn how ACTH stimulation testing guides safe steroid tapers and prevents adrenal crisis after long-term steroid use. Key protocols, testing thresholds, and real-world challenges explained.