Guidelines for hematological monitoring of patients taking clozapine

TABLE 4-4. Guidelines for hematological monitoring of patients taking clozapine 

Initial white blood cell (WBC) count must be greater than 3,500/mm, and absolute neutrophil count (ANC) must be greater than 2,000/mm.  

Weekly WBC count and ANC are required for the first 6 months of treatment and for 4 weeks after discontinuation of clozapine. After 6 months, monitoring is required every 2 weeks and after 12 months, monitoring is required every 4 weeks. 

If WBC count is 2,000-3,000/mm or ANC is 1,000-1,500/mm, interrupt therapy and monitor for signs of infection. Perform WBC and differential counts daily. If there are no symptoms of infection, if WBC count returns to greater than 3,000/mm, and if ANC is greater than 1,500/mm, resume clozapine therapy with twice-weekly WBC and differential counts until total WBC count returns to more than 3,500/mm and ANC is greater than 2,000/mm.  

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