A 38-year-old man with newly diagnosed hypertension is found to have a 5 cm right adrenal mass. 24-hour urine shows elevated VMA (vanillylmandelc acid) and metanephrines. Regarding VMA, which statement is correct?

• A VMA has higher sensitivity than plasma free metanephrines for pheochromocytoma screening
• B VMA is a direct precursor of epinephrine and is measured in plasma
• C VMA is secreted exclusively by extra-adrenal paragangliomas
• D VMA is the end product of catecholamine metabolism, measured in 24-hour urine, and is elevated in pheochromocytoma ✓

Explanation

VMA is the end metabolite of catecholamines (epinephrine and norepinephrine) excreted in urine and elevated in pheochromocytoma. It is not a precursor. It is elevated in both adrenal and extra-adrenal tumors. Plasma free metanephrines have higher sensitivity than VMA and are now the preferred screening test per Endocrine Society guidelines.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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