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

The most common cause of Cushing's syndrome is iatrogenic from glucocorticoids. Cushing's syndrome results from excess levels of cortisol in the body, and one of the most prevalent contributors to this condition is the use of corticosteroid medications. Patients receiving glucocorticoid therapy for various conditions such as autoimmune disorders, asthma, or transplant rejection can develop Cushing's syndrome due to the high doses or prolonged use of these medications.

When glucocorticoids are administered, they mimic the effects of cortisol, leading to the symptoms associated with Cushing's syndrome, such as weight gain, hypertension, and alterations in metabolism. It is crucial for healthcare providers to monitor patients on glucocorticoids closely for these potential side effects, making an understanding of iatrogenic causes particularly relevant in clinical practice.

Other causes of Cushing's syndrome, while significant, are less common compared to iatrogenic sources. Adrenal tumors and pituitary adenomas, which can lead to endogenous production of cortisol, occur less frequently than cases arising from exogenous glucocorticoid use. This highlights the importance of considering medication history when evaluating a patient for Cushing's syndrome.