Inappropriate adrenocorticotropic hormone (ACTH) secretion, also known as ACTH-dependent Cushing's syndrome, refers to a medical condition characterized by the excessive production and release of ACTH from the pituitary gland. This aberrant secretion leads to increased corticotropin-releasing hormone (CRH) production, resulting in the overstimulation of the adrenal glands and an overproduction of cortisol.
ACTH is a hormone produced by the pituitary gland that regulates the production and release of cortisol, a stress hormone, by the adrenal glands. In normal circumstances, ACTH secretion is controlled by a negative feedback loop, where high levels of cortisol inhibit its production. However, in cases of inappropriate ACTH secretion, this regulation is disrupted, and high levels of ACTH continue to be produced despite already elevated cortisol levels.
The excessive levels of cortisol in the blood can have numerous adverse effects on the body, including weight gain, especially in the face, neck, and torso, thinning of the skin, muscle wasting, easy bruising, impaired wound healing, high blood pressure, diabetes, osteoporosis, and mood disturbances.
The most common cause of inappropriate ACTH secretion is a benign tumor in the pituitary gland called a pituitary adenoma, which disrupts the normal regulation of ACTH production and release. However, some cases may arise from other tumors or conditions outside the pituitary gland, such as lung or pancreatic tumors, termed ectopic ACTH secretion.
Treatment for inappropriate ACTH secretion depends on the underlying cause and may include surgical removal of the tumor, radiation therapy, or medications to suppress cortisol production.
