Azathioprine – Agranulocytosis Emergency — SCE Neurology MCQ

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ModeratePeripheral Neuropathy & NeuromuscularAzathioprine – Agranulocytosis EmergencySCE Neurology

A 70-year-old woman with known MG on azathioprine develops a fever and sore throat. FBC shows WCC 0.8 × 10⁹/L with neutrophils 0.1 × 10⁹/L. What is the diagnosis and the immediate management?

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Correct answer: C — Azathioprine-induced agranulocytosis — stop azathioprine immediately, take blood cultures, and start empirical broad-spectrum IV antibiotics (neutropenic sepsis protocol)

Azathioprine can cause myelosuppression including potentially fatal agranulocytosis (neutrophil count <0.5 × 10⁹/L), particularly in patients with low TPMT activity (though this was checked before starting). This patient has severe neutropenia (0.1 × 10⁹/L) with fever — this constitutes neutropenic sepsis, a medical emergency. Management: (1) stop azathioprine immediately, (2) take blood cultures and other septic screen, (3) start empirical broad-spectrum IV antibiotics immediately (per local neutropenic sepsis protocol — e.g. piperacillin-tazobactam), (4) monitor FBC daily, (5) haematology review. A: This is not a simple URTI — the neutrophil count is critically low. C: The FBC findings indicate drug toxicity, not MG relapse. D: This is severely abnormal. E: The dose should be stopped, not increased.

Reference: ABN MG Guidelines (2025); BNF – Azathioprine; NICE NG151 Neutropenic Sepsis