High ACTH levels usually occur when the body isn’t producing enough cortisol or when there’s an overactive pituitary gland or tumor. The pituitary releases extra ACTH to compensate for low cortisol.

Common Causes

• Addison’s disease (adrenal gland damage).
• Pituitary tumors (Cushing’s disease).
• Ectopic ACTH syndrome (ACTH made outside the pituitary).