Which combination of findings would most support a diagnosis of Cushing disease?

• A. Elevated cortisol with elevated serum sodium
• B. Elevated cortisol with low sodium
• C. Normal cortisol with low sodium
• D. Low cortisol with high sodium

Answer: (A)

Excess cortisol from pituitary ACTH overproduction drives Cushing disease. When cortisol is chronically high, it can act on mineralocorticoid receptors in the kidney, promoting sodium and water retention. That makes elevated sodium a plausible accompanying finding with high cortisol. So this combination—high cortisol with high serum sodium—best fits the hormone pattern seen in Cushing disease. The other patterns don't align with cortisol’s effects: cortisol would not be expected to be normal or low in this setting, and a low sodium finding would not reflect the sodium-retaining influence of cortisol excess.