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Phosphocreatine system — MRCP Part 1 MCQ

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HardExercise PhysiologyPhosphocreatine systemMRCP Part 1

A patient taking propylthiouracil develops fever, mouth ulcers and a severe sore throat. Which serious adverse reaction is most likely?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: B — Severe neutropenia from antithyroid-drug agranulocytosis

The best answer is “Severe neutropenia from antithyroid-drug agranulocytosis”. This symptom cluster during antithyroid treatment is characteristic of potentially fatal agranulocytosis. Propylthiouracil is stopped and an urgent full blood count obtained; the patient needs prompt clinical assessment and must not restart an antithyroid drug without specialist advice. Hypothyroidism, eye disease and adrenergic symptoms do not explain the infection phenotype.

Reference: NHS Specialist Pharmacy Service: Propylthiouracil monitoring: https://www.sps.nhs.uk/monitorings/propylthiouracil-monitoring/