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Endocrinology

Investigations for phaeochromocytoma

How to order and read plasma free metanephrines (supine sampling, age-adjusted normetanephrine, the 3-times rule, the metabolite pattern), when to repeat or do a clonidine suppression test, and which scan to choose once biochemistry is positive.

Tier 2Medical sciences concept

Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made

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At a glance

  • Biochemistry before imaging. Plasma free metanephrines (or 24-hour urine fractionated metanephrines) come first; scans follow a positive result.
  • Metanephrines are made continuously inside the tumour, so they stay raised between paroxysms. Plasma catecholamines and urine VMA are obsolete.
  • Normal plasma metanephrines (drawn properly) all but exclude a secreting tumour. The exceptions are small tumours, biochemically silent head and neck paragangliomas and some SDHx tumours.

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Last updated
14 November 2026
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