Corticotropin Test in Hawaii

What this test measures

The pituitary gland releases ACTH in pulses, and the hormone travels through the bloodstream to the adrenal glands. There it stimulates cortisol production. Because the two hormones work as a feedback loop, measuring ACTH without cortisol often leaves the picture incomplete, so laboratories and clinicians frequently review them together.

Testing may be requested when someone reports persistent fatigue, unexplained weight changes, low blood pressure, or other symptoms that raise concern about adrenal function. It can also be part of an evaluation for Cushing syndrome, adrenal insufficiency, or a pituitary disorder. Some clinicians use it to follow a known condition over time.

Interpretation depends on context. A high ACTH with a low cortisol points in one direction, while a low ACTH with a high cortisol points in another. Results can be affected by the time of day, stress, and medications, so clinicians consider the whole clinical picture before drawing conclusions.