Which condition corresponds to Cushing's syndrome due to autonomous adrenal cortisol production?

• A. Primary hypercorticolism
• B. Secondary hypercorticolism
• C. Inappropriate ACTH production
• D. Ectopic Cushing syndrome

Answer: (A)

This item tests the distinction between ACTH-independent and ACTH-dependent Cushing syndrome. When the adrenal gland autonomously overproduces cortisol, the pituitary senses the high cortisol and shuts down ACTH production via negative feedback. The result is low (suppressed) ACTH levels, indicating an adrenal (primary) source of cortisol excess. That’s why primary hypercortisolism best fits autonomous adrenal cortisol production.

In contrast, ACTH-dependent causes (pituitary or ectopic ACTH production) raise ACTH levels and drive cortisol up, so they would not align with autonomous adrenal cortisol output. The idea of inappropriate ACTH production likewise implies ACTH is not properly regulated (typically elevated or inappropriately normal) in the setting of cortisol excess, which again points away from adrenal-autonomous production.