Cushing's syndrome is also known as hyperadrenalism because it affects which adrenal zones?

• A. Zona glomerulosa only
• B. Zona fasciculata only
• C. All adrenal cortical zones
• D. Adrenal medulla

Answer: (C)

Cushing's syndrome reflects a state of excessive glucocorticoid production from the adrenal cortex. The cortex has three zones: glomerulosa (mineralocorticoids), fasciculata (glucocorticoids like cortisol), and reticularis (androgens). When Cushing's is driven by excess ACTH, this pituitary hormone stimulates the entire adrenal cortex, leading to enlargement and increased activity across all cortical zones. The main excess hormone is cortisol from the fasciculata, but the trophic effect of ACTH causes the whole cortex to be hyperactive, so the condition is described as affecting all adrenal cortical zones. The adrenal medulla is not involved, as it secretes catecholamines rather than steroids.