Clozapine Monitoring — MRCPsych Paper B MCQ

Instant feedback + full explanation. One question, done properly.

EasySchizophrenia & PsychosisClozapine MonitoringMRCPsych Paper B

A 28-year-old woman has started clozapine in the UK. Her baseline white blood cell count and absolute neutrophil count are satisfactory, and subsequent results remain within the routine monitoring range. How frequently should her full blood count, including a differential count, be monitored during the first 18 weeks of treatment?

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

Reveal the answer and explanation

Correct answer: E — Weekly

The correct answer is E: weekly. Under UK clozapine monitoring requirements, the white blood cell count and differential count, including the absolute neutrophil count, must be checked at least weekly during the first 18 weeks. This monitoring is required because clozapine can cause potentially fatal neutropenia or agranulocytosis, with the risk being greatest early in treatment. Every 2 weeks applies between weeks 18 and 52 under the UK monitoring schedule, while monitoring may become every 4 weeks after one year if neutrophil counts remain stable. Daily testing is not routine and may be required only when clinically significant haematological abnormalities occur. Monthly and every-6-week monitoring are therefore insufficient during initiation.

Reference: Electronic Medicines Compendium, Clozapine Viatris 100 mg Tablets, Summary of Product Characteristics, UK Clozaril Official Recommendations and section 4.4, revised February 2026. https://www.medicines.org.uk/emc/product/15498/smpc