What testing modality is preferred for diagnosing pheochromocytoma?

What testing modality is preferred for diagnosing pheochromocytoma?

• A. Plasma free metanephrines or 24-hour urine fractionated metanephrines/catecholamines; imaging after a positive test.
• B. Serum cortisol
• C. Plasma ACTH
• D. Urine vanillylmandelic acid only

Answer: (A)

Diagnosing pheochromocytoma relies on biochemical testing that can reliably detect catecholamine production from the tumor, even when secretion is episodic. Metanephrines, which are produced continuously from catecholamines by tumor tissue, serve as highly sensitive biomarkers. Measuring them in plasma as free metanephrines or in a 24-hour urine collection for fractionated metanephrines and catecholamines captures this signal effectively, making these approaches the preferred screening options. After a positive biochemical test, imaging with CT or MRI (and sometimes functional imaging) is used to localize the tumor. Serum cortisol or ACTH are not used to diagnose pheochromocytoma, and urine vanillylmandelic acid alone has lower sensitivity and specificity, so it is not the preferred method.

Diagnosing pheochromocytoma relies on biochemical testing that can reliably detect catecholamine production from the tumor, even when secretion is episodic. Metanephrines, which are produced continuously from catecholamines by tumor tissue, serve as highly sensitive biomarkers. Measuring them in plasma as free metanephrines or in a 24-hour urine collection for fractionated metanephrines and catecholamines captures this signal effectively, making these approaches the preferred screening options. After a positive biochemical test, imaging with CT or MRI (and sometimes functional imaging) is used to localize the tumor. Serum cortisol or ACTH are not used to diagnose pheochromocytoma, and urine vanillylmandelic acid alone has lower sensitivity and specificity, so it is not the preferred method.