Primary hyperaldosteronism is confirmed biochemically. Adrenal CT shows bilateral normal glands. What is the most important next investigation before deciding on unilateral adrenalectomy?
- A Adrenal vein sampling (AVS) ✓
- B Dexamethasone suppression test
- C Adrenal scintigraphy with NP-59
- D Repeat CT with 3 mm slices
Correct answer: A. Adrenal vein sampling (AVS)
Explanation
Adrenal vein sampling (AVS) is the gold standard for differentiating unilateral aldosterone-producing adenoma from bilateral adrenal hyperplasia when CT is normal or shows bilateral changes. CT has poor sensitivity for small adenomas and cannot reliably lateralise aldosterone excess. The Endocrine Society guidelines recommend AVS in all patients fit for surgery before deciding on adrenalectomy. NP-59 scintigraphy is less available and less accurate. Dexamethasone suppression is for Cushing's syndrome.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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