What is the most common cause of Cushing's syndrome?

The most common cause of Cushing's syndrome is the overuse of corticosteroids. Cushing's syndrome is characterized by excess levels of cortisol in the blood, and one of the most prevalent ways this can occur is through the administration of corticosteroid medications. These drugs are often prescribed for a variety of conditions, including autoimmune diseases and inflammatory conditions, and when taken in high doses or for extended periods, they can lead to a condition that mimics endogenous hypercortisolism.

While other causes such as pituitary adenomas, adrenal hyperplasia, and ectopic ACTH production by tumors can contribute to the development of Cushing's syndrome, they are less common in clinical practice compared to the iatrogenic effects of corticosteroid use. Recognizing the role of corticosteroids in causing this syndrome is crucial for diagnosing and managing patients, especially those with a relevant medical history of corticosteroid treatment.