ACTH Stimulation Test, 1-Hour

This test evaluates how well the adrenal glands respond to adrenocorticotropic hormone (ACTH). It involves measuring cortisol levels before and after administering synthetic ACTH. The one-hour version checks the cortisol level exactly one hour after the injection. It helps determine if the adrenal glands are functioning properly, especially in conditions suspected of adrenal insufficiency or Addison’s disease.

Cortisol is vital for various body functions including metabolism, immune response, and stress management. If the adrenal glands are not producing enough cortisol, it can result in fatigue, hypotension, or even adrenal crisis. The ACTH stimulation test helps in diagnosing primary adrenal insufficiency, secondary adrenal insufficiency, or hypopituitarism.

 It is commonly done when a patient shows symptoms of adrenal dysfunction, such as unexplained fatigue, low blood pressure, or electrolyte imbalance. It is also used in the follow-up of known cases of pituitary or adrenal disease.

A normal result shows a significant increase in cortisol after ACTH administration. A blunted or no response suggests adrenal insufficiency. If the cortisol rises modestly, it may indicate secondary adrenal insufficiency due to pituitary failure rather than a primary adrenal issue.

A baseline blood sample is collected for cortisol. Then synthetic ACTH is administered intramuscularly or intravenously, and another sample is collected at the one-hour mark. Both samples are tested for cortisol levels and compared.