Which test should be used to help confirm pheochromocytoma?

Which test should be used to help confirm pheochromocytoma?

• A. Serum cortisol
• B. Plasma metanephrines
• C. Fasting glucose
• D. 24-hour urine vanillylmandelic acid

Answer: (D)

Detecting pheochromocytoma hinges on measuring the products of catecholamine metabolism. Metanephrines are produced continuously by the tumor and remain elevated between spells, making plasma free metanephrines the most sensitive and reliable test to confirm the diagnosis. A 24-hour urine test for vanillylmandelic acid can be informative but is less sensitive and specific, with results influenced by diet and other factors, so it’s not the best choice for confirmation. Fasting glucose and serum cortisol don’t directly indicate pheochromocytoma and aren’t used to confirm it.