In a patient being evaluated for Cushing disease, which lab pattern would most strongly indicate the disease when considered with cortisol?

In a patient being evaluated for Cushing disease, which lab pattern would most strongly indicate the disease when considered with cortisol?

• A. Elevated cortisol with elevated sodium
• B. Elevated cortisol with low sodium
• C. Elevated cortisol with low glucose
• D. Elevated cortisol with low calcium

Answer: (A)

In Cushing disease, cortisol is chronically elevated, and cortisol can exert mineralocorticoid-like effects in the kidney, promoting sodium and water retention. This often leads to higher sodium levels and can contribute to hypertension seen with hypercortisolism. So when you pair elevated cortisol with elevated sodium, it fits the expected physiologic pattern of Cushing disease best. The other patterns don’t align as well: cortisol excess tends to raise glucose, so a low glucose level isn’t typical; sodium is usually not low in this context due to the sodium-retaining effect; calcium isn’t a defining lab change in Cushing—so elevated sodium remains the most characteristic companion to high cortisol.

In Cushing disease, cortisol is chronically elevated, and cortisol can exert mineralocorticoid-like effects in the kidney, promoting sodium and water retention. This often leads to higher sodium levels and can contribute to hypertension seen with hypercortisolism. So when you pair elevated cortisol with elevated sodium, it fits the expected physiologic pattern of Cushing disease best.

The other patterns don’t align as well: cortisol excess tends to raise glucose, so a low glucose level isn’t typical; sodium is usually not low in this context due to the sodium-retaining effect; calcium isn’t a defining lab change in Cushing—so elevated sodium remains the most characteristic companion to high cortisol.