What is the most common cause of Cushing syndrome?

The most common cause of Cushing syndrome is indeed related to steroid use. This condition arises due to prolonged exposure to elevated levels of cortisol or similar glucocorticoids, which can occur through the administration of exogenous corticosteroids. Medications such as prednisone, dexamethasone, and hydrocortisone are frequently prescribed for various inflammatory conditions, autoimmune diseases, and even after organ transplantation. When these steroids are used over a long duration, they can lead to characteristic features of Cushing syndrome, including obesity, hypertension, hyperglycemia, and a distinctive fat distribution termed "moon facies."

Understanding this etiology is crucial for healthcare providers, as it can help them recognize the symptoms early and assess steroid use in patients. Effective management of Cushing syndrome frequently necessitates addressing the underlying cause, which in this scenario involves either tapering the steroid medication or switching to a lower dose or alternative treatments if possible.