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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
Key points
- Catecholamine-secreting tumour from chromaffin cells — usually adrenal medulla (90%), or extra-adrenal paraganglioma (10%)
- Classic triad: episodic headache + sweating + palpitations/tachycardia, with hypertension (paroxysmal or sustained)
- Diagnosis: plasma free metanephrines (most sensitive) or 24 h urinary metanephrines/catecholamines
- Imaging: CT/MRI abdomen for localisation. MIBG scan or PET for extra-adrenal/metastatic disease
- Pre-operative management: alpha-blocker (phenoxybenzamine) for ≥10–14 days BEFORE beta-blocker BEFORE surgery
- Surgery: laparoscopic adrenalectomy after adequate alpha-blockade. Genetic testing for all patients (>40% have germline mutations)
Overview
Phaeochromocytoma is a rare catecholamine-secreting neuroendocrine tumour arising from chromaffin cells of the adrenal medulla. Extra-adrenal catecholamine-secreting tumours are called paragangliomas and can occur anywhere along the sympathetic chain. These tumours secrete adrenaline, noradrenaline, and/or dopamine in an uncontrolled manner, causing episodic or sustained hypertension and hyperadrenergic symptoms. The "rule of 10s" (historical) states: 10% bilateral, 10% malignant, 10% extra-adrenal, 10% familial, 10% in children — though updated data suggests familial/genetic rates are much higher (~40%). Key genetic associations include MEN2A/2B (RET mutations), von Hippel-Lindau syndrome (VHL), neurofibromatosis type 1 (NF1), and succinate dehydrogenase (SDH) gene mutations.
Epidemiology
Annual incidence is approximately 2–8 per million population. It accounts for <1% of all hypertension but is an important secondary cause to identify because it is potentially curable and potentially lethal if unrecognised (hypertensive crisis, cardiomyopathy, stroke). Peak incidence is 30–50 years. No significant sex predilection. Approximately 40% of patients have an identifiable germline genetic mutation — genetic testing is now recommended for all patients. Malignancy rate is ~10% for adrenal phaeochromocytoma and higher for paragangliomas (particularly SDHB-mutated tumours).
Clinical Features
Symptoms
Episodic headache — severe, throbbing, paroxysmal
Episodic sweating — profuse, diaphoresis
Palpitations and tachycardia — often paroxysmal
Anxiety, tremor, sense of impending doom during attacks
Pallor (vasoconstriction — NOT flushing)
Paroxysmal or sustained hypertension — may be severe and refractory
Orthostatic hypotension (paradoxical — from volume contraction)
Signs
Hypertension — sustained or paroxysmal. May be severe (>200/120 mmHg)
Tachycardia during paroxysm
Postural hypotension between attacks (intravascular volume depletion)
Pallor during attacks (catecholamine-mediated vasoconstriction)
Signs of MEN2: thyroid nodule/goitre (medullary thyroid cancer), mucosal neuromas (MEN2B), Marfanoid habitus
Hypertensive crisis with anaesthesia, surgery, abdominal palpation, or certain drugs if undiagnosed
Investigations
First-line
Plasma free metanephrinesMost sensitive test (~97–99%). Measures normetanephrine and metanephrine. Sample sitting or supine. Elevated = highly suggestive
24 h urinary metanephrines and catecholaminesAlternative to plasma. Collect 2 separate 24 h urine specimens. Elevated normetanephrine/metanephrine confirms diagnosis
Second-line
CT or MRI abdomen (adrenals)Localise tumour. MRI preferred (better tissue characterisation, no radiation). Adrenal phaeochromocytoma appears bright on T2-weighted MRI ("lightbulb sign")
MIBG (meta-iodobenzylguanidine) scintigraphyFunctional imaging — confirms catecholamine-secreting tissue. Used for extra-adrenal or metastatic disease
Specialist
⁶⁸Ga-DOTATATE PET/CTSuperior to MIBG for localising extra-adrenal paragangliomas and metastatic disease
Genetic testingRecommended for ALL patients — RET (MEN2), VHL, NF1, SDHB/C/D mutations. Cascade family screening if positive
EchocardiogramAssess for catecholamine-induced cardiomyopathy (dilated or stress/Takotsubo)
1
Pre-operative medical preparation (ESSENTIAL)
- Alpha-blocker FIRST: phenoxybenzamine (irreversible, non-selective) — start 10 mg BD, titrate up to 1 mg/kg/day. OR doxazosin (selective alpha-1)
- Start alpha-blockade ≥10–14 days before surgery
- Beta-blocker ONLY AFTER adequate alpha-blockade (usually 2–3 days before surgery): propranolol or atenolol
- NEVER give beta-blocker BEFORE alpha-blocker — unopposed alpha stimulation causes hypertensive crisis
- Volume expansion: high-salt diet and liberal fluids (reverses catecholamine-induced volume contraction)
- Target: sitting BP <130/80, standing systolic >90, HR 60–70 sitting, no orthostatic hypotension
2
Surgery
- Laparoscopic adrenalectomy: curative in >90% of benign adrenal phaeochromocytoma
- Open surgery if large (>6 cm), invasive, or paraganglioma in complex location
- Intra-operative BP management: IV phentolamine (alpha-blocker) for hypertensive surges, IV noradrenaline/phenylephrine for hypotension after tumour removal
- Post-operative: monitor for hypotension and hypoglycaemia (sudden catecholamine withdrawal)
3
Malignant/metastatic disease
- No curative treatment — survival variable
- MIBG therapy (¹³¹I-MIBG): targeted radionuclide therapy
- Chemotherapy: cyclophosphamide + vincristine + dacarbazine (CVD regimen)
- Tyrosine kinase inhibitors: sunitinib. Clinical trials available
4
Follow-up and genetic
- Annual biochemical surveillance (plasma/urine metanephrines) — recurrence can occur years later
- Genetic testing and counselling for all. Family screening if mutation found
- If MEN2: screen for medullary thyroid cancer (calcitonin) and hyperparathyroidism (calcium/PTH)
Complications
- Hypertensive crisis: Uncontrolled catecholamine surge — stroke, MI, aortic dissection, pulmonary oedema. Can be triggered by anaesthesia, abdominal palpation, certain drugs (metoclopramide, tricyclics, opioids)
- Cardiomyopathy: Catecholamine-induced dilated or Takotsubo cardiomyopathy — may present with heart failure
- Stroke and MI: From severe hypertension during catecholamine surges
- Malignancy: ~10% of adrenal phaeochromocytoma, higher for paragangliomas (especially SDHB mutations)
- Post-operative hypotension and hypoglycaemia: After tumour removal — sudden loss of catecholamine excess
UKMLA Exam Tips
- 1Classic triad: episodic HEADACHE + SWEATING + PALPITATIONS with hypertension. Think "Pheo" with any paroxysmal hypertension
- 2PALLOR during attacks (vasoconstriction), NOT flushing — this distinguishes from carcinoid syndrome
- 3Alpha-block BEFORE beta-block. NEVER beta-block first — unopposed alpha = hypertensive crisis
- 4Plasma free metanephrines = most sensitive screening test. Urinary catecholamines also acceptable
- 5MEN2: medullary thyroid cancer + phaeochromocytoma + hyperparathyroidism. Always screen for phaeo BEFORE thyroid surgery
- 6"Rule of 10s" is outdated — genetic mutations found in ~40%. Test ALL patients genetically
- 7If adrenal incidentaloma found on CT: always exclude phaeochromocytoma before biopsy or surgery (risk of crisis)
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