Why does Cushing's syndrome, characterized by excessive cortisol, sometimes arise from pituitary tumors that secrete ACTH, rather than directly from adrenal gland malfunctions?

💡 Explanation

ACTH-secreting pituitary tumors cause Cushing's because the elevated ACTH levels override the normal negative feedback loop that would typically suppress ACTH production in response to high cortisol levels. Therefore, cortisol levels remain elevated, rather than being regulated by the pituitary-adrenal axis under normal conditions.

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