Morning pseudoneutropenia during clozapine treatment

Clozapine, an atypical antipsychotic drug, is associated with a high risk of neutropenia and agranulocytosis, necessitating the immediate discontinuation of the drug. We report the case of a patient who developed clozapine-induced neutropenia. Assessments revealed a pronounced diurnal variation in the number of circulating neutrophils (1200-1900/mm(3) in the morning and 2200-2700/mm(3) in the afternoon). Due to these circadian changes, we decided to continue clozapine treatment.