Phaeochromocytoma Diagnosis — RACP Adult Medicine MCQ

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EasyEndocrinology & DiabetesPhaeochromocytoma DiagnosisRACP Adult Medicine

A 40-year-old woman with suspected phaeochromocytoma is being investigated. Which test has the highest sensitivity for diagnosis?

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Correct answer: D — Plasma free metanephrines

Plasma free metanephrines (metanephrine and normetanephrine) have the highest sensitivity (96–99%) for phaeochromocytoma/paraganglioma diagnosis. They are produced continuously by catechol-O-methyltransferase within chromaffin tumour cells, independent of episodic catecholamine secretion. A normal plasma free metanephrines result essentially excludes the diagnosis. Elevated results require confirmation and imaging (CT/MRI abdomen, then functional imaging with 123I-MIBG or 68Ga-DOTATATE PET if needed).

Reference: eTG – 2025 – Endocrinology; Endocrine Society – 2014 – Phaeochromocytoma Guidelines