Phaeochromocytoma
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Direct answer
Episodic headache, sweating and palpitations — the classic triad — with paroxysmal or sustained hypertension, point to phaeochromocytoma, a catecholamine-secreting tumour of chromaffin tissue, usually the adrenal medulla. Diagnosis is biochemical with plasma free metanephrines or 24-hour urinary fractionated metanephrines, followed by CT or MRI localisation. Before surgery, alpha-blockade (phenoxybenzamine or doxazosin) with volume expansion is established first and a beta-blocker is added only afterwards — beta-blockade first precipitates hypertensive crisis from unopposed alpha vasoconstriction.
What you must remember
- Best test: plasma free metanephrines (most sensitive) or 24-hour urinary fractionated metanephrines; they are continuous metabolites and outperform catecholamine measurement.
- Avoid false positives: withdraw caffeine, decongestants, paracetamol (in some assays), tricyclic antidepressants and monoamine oxidase inhibitors, and sample during calm conditions or major stress.
- Localisation: adrenal CT or MRI — the tumour classically shows a bright T2 "light-bulb" appearance; iodine-123 MIBG scintigraphy or newer DOTATATE PET for extra-adrenal, metastatic or suspected familial disease; never biopsy a suspected phaeochromocytoma, as it can trigger a crisis.
- Rule of 10s: roughly 10 per cent bilateral, 10 per cent extra-adrenal (paraganglioma, e.g., organ of Zuckerkandl), 10 per cent malignant and 10 per cent familial — the fractions are higher in children and syndromic patients.
- Familial associations: MEN 2A and 2B (RET proto-oncogene, with medullary thyroid carcinoma and, in 2A, primary hyperparathyroidism), von Hippel-Lindau disease, neurofibromatosis type 1 and succinate dehydrogenase gene mutations causing paraganglioma syndromes — genetic testing is offered to most patients in current practice.
- Preoperative preparation: an alpha-blocker for 10 to 14 days with liberal salt and fluid intake, until nasal congestion appears and postural blood pressure stabilises, then add a beta-blocker for tachycardia or arrhythmia; intraoperative haemodynamic instability is expected.
- Hypertensive crisis is treated with intravenous phentolamine or nitroprusside; screen every adrenal incidentaloma with metanephrines before biopsy or surgery.
Spells, then surgery: the sequence end to end
A 40-year-old woman describes 20-minute spells of pounding headache, drenching sweat and palpitations, with hypertension fluctuating between visits; the triad occurring together during spells is highly suggestive, while labile hypertension alone is usually essential. Biochemistry first, and the best test is plasma free metanephrines or 24-hour urinary fractionated metanephrines — metabolites produced continuously within the tumour and more sensitive than catecholamines themselves — after withdrawing caffeine, decongestants, paracetamol (in some assays), tricyclics and monoamine oxidase inhibitors, and sampling in calm conditions. Positive results send her to adrenal CT or MRI, where the tumour may show the bright T2 "light-bulb" appearance; One prohibition governs imaging: never biopsy a suspected phaeochromocytoma — provoking it can release a catastrophic catecholamine surge, and the same rule explains why every adrenal incidentaloma gets metanephrines before biopsy or surgery. Now the preoperative discipline: phenoxybenzamine or doxazosin for 10 to 14 days with liberal salt and fluid, until nasal congestion appears and postural pressure stabilises, and only then a beta-blocker for tachycardia or arrhythmia — reversing that order leaves alpha receptors unopposed and precipitates crisis. Intraoperative haemodynamic swings are expected regardless; a crisis at any stage is treated with intravenous phentolamine or nitroprusside. Alongside, remember the rule of 10s (roughly 10 per cent each bilateral, extra-adrenal, malignant and familial, higher in children and syndromic patients) and offer genetic testing, since MEN 2A and 2B (RET, with medullary thyroid carcinoma), von Hippel-Lindau disease, neurofibromatosis type 1 and succinate dehydrogenase paraganglioma syndromes hide in a sizable share.
Where students slip
Almost every year the sequencing question appears, answered by mechanism: beta-blockade first leaves alpha-mediated vasoconstriction unopposed, so alpha first, volume, then beta. The test-choice error follows — catecholamines instead of metanephrines — and the false-positive list explains why an unprepared sample misleads. The syndrome mix-up is the third: MEN 1 is parathyroid, pancreatic and pituitary; MEN 2 is thyroid, adrenal medulla and parathyroid in 2A or mucosal neuromas in 2B — phaeochromocytoma with medullary thyroid carcinoma is RET, every time. And the biopsy caution is examined as a "next step" where the wrong option is the needle.
Frequently asked questions
What is the best diagnostic test?
Plasma free metanephrines or 24-hour urinary fractionated metanephrines — catecholamine metabolites produced continuously within the tumour, more sensitive than catecholamines themselves.
What is the rule of 10s?
Roughly 10 per cent each are bilateral, extra-adrenal (paragangliomas), malignant and familial, with higher proportions in children and hereditary syndromes.
Why must alpha-blockade precede beta-blockade?
Beta-blockade first leaves alpha-mediated vasoconstriction unopposed and can precipitate a hypertensive crisis; block alpha first, volume-load, then add a beta-blocker.
Which genetic syndromes are associated?
MEN 2A and 2B (RET mutations) with medullary thyroid carcinoma, von Hippel-Lindau disease, neurofibromatosis type 1 and succinate dehydrogenase paraganglioma syndromes.
Why is biopsy avoided?
Provoking the tumour can release a catastrophic catecholamine surge; diagnosis is biochemical and imaging-based, with histology after adrenalectomy.
How is a crisis managed?
Intravenous phentolamine or nitroprusside for blood pressure, beta-blockade for tachyarrhythmia once alpha-blocked, then definitive tumour removal.