In unilateral suspected hyperaldosteronism, why is adrenal venous sampling used?

• A. To measure cortisol levels
• B. To lateralize aldosterone secretion before surgical adrenalectomy when imaging is inconclusive
• C. To assess metastatic potential
• D. To replace imaging

Answer: (B)

In this situation, the critical decision is whether the excess aldosterone is coming from one adrenal gland or both. Imaging alone often can’t tell this reliably, because a person may have an incidental adrenal lesion that isn’t causing the overproduction. Adrenal venous sampling directly compares aldosterone production from each gland, which lets us determine which side is driving the problem and whether surgery could be curative.

The test works by sampling blood from both adrenal veins and from the systemic circulation, then measuring aldosterone and cortisol. The cortisol data help confirm that the samples truly come from the adrenal veins and are used to correct for dilution. By calculating the aldosterone-to-cortisol ratios on each side, the clinician sees which gland is producing much more aldosterone. If one side is clearly dominant, surgical removal of that adrenal gland can resolve the excess production and potentially cure the hypertension. If both glands contribute, medical therapy with mineralocorticoid receptor antagonists is preferred.

So, the purpose is to lateralize aldosterone secretion to guide surgical decision-making, especially when imaging doesn’t provide a clear answer.