ACTH An ACTH test measures the level of Adrenocorticotropic Hormone (ACTH) in your blood. It's a blood test used to assess the function of the adrenal and pituitary glands, especially in diagnosing conditions related to cortisol production, like Cushing's syndrome and Addison's disease. Here's a more detailed explanation: What is ACTH? ACTH is a hormone produced by the pituitary gland that stimulates the adrenal glands to release cortisol, which is also known as the 'stress hormone'. Why is it tested? An ACTH test is often part of a larger evaluation to diagnose problems with the pituitary or adrenal glands. It can help determine if the glands are producing too much or too little cortisol, which can lead to various health issues. How is it done? A blood sample is drawn from a vein in your arm. Sometimes, an ACTH stimulation test is also performed, where you receive an injection of synthetic ACTH, and blood samples are taken to measure cortisol levels before and after the injection. What can it tell you? High ACTH: May indicate Cushing's syndrome, where the body produces too much cortisol. Low ACTH: Can suggest Addison's disease, where the adrenal glands don't produce enough cortisol. Normal ACTH: May be a sign that your pituitary and adrenal glands are functioning properly. When might it be recommended? Your doctor might recommend an ACTH test if you have symptoms related to hormone imbalances, such as weight fluctuations, fatigue, muscle weakness, or skin changes.