A 45-year-old woman presents with episodic headaches, palpitations, and sweating. During an episode, BP is 220/130 mmHg. MRI reveals a 3 cm adrenal mass. Which biochemical test has the highest sensitivity for confirming the diagnosis?

• A 24-hour urine vanillylmandelic acid
• B Serum chromogranin A
• C 24-hour urine catecholamines
• D Plasma free metanephrines ✓

Explanation

Plasma free metanephrines have the highest sensitivity (>96%) for pheochromocytoma and are the recommended first-line test. Metanephrines are produced continuously within tumor cells, making them superior to catecholamines which are released episodically. VMA has lower sensitivity. Chromogranin A is nonspecific and not recommended as a primary screening test. The classic triad of headache, palpitations, and sweating with episodic hypertension is characteristic.

Reference: Williams Textbook of Endocrinology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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