In primary adrenal insufficiency, cortisol response to ACTH stimulation is best described as?

• A. Significant increase
• B. Moderate increase
• C. No change or minimal increase
• D. Rapid decrease

Answer: (C)

When the adrenal cortex is damaged, as in primary adrenal insufficiency, it cannot mount a robust cortisol release even when stimulated by ACTH. The ACTH stimulation test challenges the adrenal glands to see how much cortisol they can produce. If the cortex is seriously impaired, there won’t be a meaningful rise in cortisol after the stimulus. That’s why the best description is no change or only a minimal increase.

A significant or moderate increase would mean the adrenal cortex still has functional tissue capable of responding to ACTH, which is not the case in primary adrenal insufficiency. A rapid decrease after ACTH isn’t a typical pattern and doesn’t reflect the expected response in this condition.