Makindo Medical Notes

💡 Hypertension in phaeochromocytoma is best treated with phenoxybenzamine, a non-selective α-blocker. ⚠️ Careful perioperative preparation is lifesaving: always establish α-blockade before β-blockade to avoid catastrophic hypertensive crises.

🔎 About

• Rare but important cause of secondary hypertension, particularly relevant in perioperative medicine and emergency presentations.
• Arises from chromaffin cells of the sympathetic nervous system, usually in the adrenal medulla (but may be extra-adrenal = paraganglioma).

🧬 Aetiology

• Secretes catecholamines: adrenaline, noradrenaline, dopamine.
• Occasionally secretes other peptides (opioids, endothelin, erythropoietin, neuropeptide Y).
• More common on the right; ectopic sites include bladder, mediastinum, thorax.

📊 The “10 × 10” Rule (classic)

• 10% malignant
• 10% extra-adrenal (paragangliomas)
• 10% familial (MEN2, VHL, NF1)
• 10% bilateral
• 10% in children
• 10% calcify
• 10% recur after removal
• 10% in bladder
• 10% in thorax

🔎 Update: With modern genetics, familial cases are closer to 30%.

🔬 Pathology

• Grey, vascular tumours; highly vascular on imaging.
• Paragangliomas = extra-adrenal phaeochromocytomas.

🧾 Genetic Associations

• 👁️ Von Hippel–Lindau syndrome (VHL)
• 🌿 Neurofibromatosis type 1 (NF1)
• 🧬 Multiple Endocrine Neoplasia type 2a & 2b (MEN2)

🩺 Clinical Features

• 📍 Classic triad: headache + sweating + palpitations (with hypertension).
• Hypertension: paroxysmal (spikes) or sustained.
• Other: tremor, pallor, nausea, sense of impending doom, weight loss, postural hypotension.
• Complications: arrhythmias, ACS, cardiomyopathy, stroke, hyperglycaemia.

🧪 Investigations

• Biochemistry: – 24h urinary catecholamines/metanephrines (≈98% sensitive). – Plasma metanephrines increasingly used. – FBC, U&E, calcium (screen for MEN).
• Imaging: CT/MRI adrenal. MIBG scintigraphy if equivocal or metastatic suspicion.
• Dynamic test: Clonidine suppression – catecholamines fall in normals, not in phaeochromocytoma.
• ⚠️ Never biopsy/FNA → risk of hypertensive crisis.

💊 Management

• Step 1 – α-blockade (always first) – Phenoxybenzamine (non-selective, long-acting) 10 mg BD PO → titrate. – Doxazosin (selective α1-blocker) 2–32 mg OD PO. – Phentolamine (short-acting IV) for acute crisis.
• Step 2 – β-blockade – Only after adequate α-blockade (to prevent unopposed α). – For tachycardia, arrhythmias, ACS.
• Step 3 – Surgical resection – Adrenalectomy after 2–3 weeks α-blockade. – Ensure salt & fluid preload before surgery (to avoid post-op hypotension). – Anaesthetic expertise critical: expect hypertensive crises intra-op, then sudden hypotension post-resection.

⚠️ Complications

• Cardiomyopathy (catecholamine-induced).
• Arrhythmias: AF, SVT, VT.
• Diabetes mellitus (catecholamine-driven gluconeogenesis).
• Stroke, hypertensive encephalopathy.

📚 Exam Pearls: – Always block α before β. – Classic triad = headache + sweating + palpitations. – “Rule of 10s” is exam-friendly but genetics show ~30% are familial. – Post-op hypotension is common → pre-op salt/fluid loading is vital.