Under what circumstances is adrenal venous sampling most indicated in suspected unilateral hyperaldosteronism?

• A. When imaging shows clear unilateral adenoma
• B. When imaging is inconclusive for lateralization prior to adrenalectomy
• C. When potassium is normal
• D. When renin is high

Answer: (B)

Determining which adrenal gland is producing the excess aldosterone is essential before deciding on surgery. Imaging alone often cannot reliably distinguish unilateral from bilateral disease because adrenal nodules can be incidental findings. Adrenal venous sampling directly measures aldosterone production from each adrenal vein (often using the aldosterone-to-cortisol ratio for accuracy) and provides a lateralization result that guides whether removing one gland will cure the condition. This is why AVS is most indicated when imaging is inconclusive for lateralization prior to adrenalectomy.

If imaging clearly shows a unilateral adenoma, many clinicians may proceed to surgery without AVS because the imaging and clinical picture strongly support unilateral disease. Potassium status by itself—normal versus low—does not determine the need for AVS. High renin reduces the likelihood of autonomous aldosterone production, so it is not an indication for AVS to establish unilateral disease.