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Clozapine Monitoring — MRCPsych Paper B MCQ

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ModerateSchizophrenia & PsychosisClozapine MonitoringMRCPsych Paper B

A 42-year-old man with schizophrenia is taking clozapine and is registered under the standard UK monitoring thresholds rather than the benign ethnic neutropenia thresholds. He is clinically well, but routine monitoring shows a white cell count of 3.2 × 10⁹/L and an absolute neutrophil count of 1.8 × 10⁹/L. What is the required action?

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Correct answer: E — Continue clozapine and increase blood-count monitoring to at least twice weekly

The correct answer is E. Under standard UK clozapine monitoring thresholds, a white cell count of 3.0 to less than 3.5 × 10⁹/L or an absolute neutrophil count of 1.5 to less than 2.0 × 10⁹/L is an amber result. Clozapine should be continued, with haematological monitoring increased to at least twice weekly until the counts stabilise or increase. Immediate discontinuation is required if the white cell count falls below 3.0 × 10⁹/L or the neutrophil count falls below 1.5 × 10⁹/L. Standard-frequency monitoring is therefore insufficient. Dose reduction does not manage clozapine-associated neutropenia, and prophylactic G-CSF is not routine management of an uncomplicated amber result.

Reference: Electronic Medicines Compendium, Clozapine Viatris 100 mg Tablets, Summary of Product Characteristics, section 4.4: Low WBC count/ANC and Table 1, updated 13 March 2026. https://www.medicines.org.uk/emc/product/15498/smpc