What is the most common cause of secondary adrenal insufficiency?

• A. Metyrapone therapy
• B. Glucocorticoid therapy
• C. Insulin therapy
• D. ACTH deficiency

Answer: (B)

Secondary adrenal insufficiency happens when the pituitary doesn’t produce enough ACTH, so cortisol drops even though the adrenal glands themselves are capable of making it. The most common reason for this is suppression of the hypothalamic-pituitary-adrenal axis by externally given glucocorticoids. Long-term steroid use tells the body to stop producing ACTH, and the adrenals can atrophy. If the steroids are withdrawn abruptly or during stress, cortisol may be insufficient, leading to adrenal crisis.

Other items listed don’t typically cause this pattern. Metyrapone is a drug used to test or treat certain conditions, not a common cause of secondary AI. Insulin therapy isn’t related to cortisol production. ACTH deficiency can cause secondary AI, but in practice, exogenous glucocorticoids are the more frequent culprit because they’re widely used for various conditions.