A nurse is reinforcing teaching about laboratory testing with a client who has a prescription for clozapine. Which of the following laboratory tests should the nurse instruct the client to undergo weekly for the first 6 months of treatment?

Clozapine is an atypical antipsychotic medication reserved for treatment-resistant schizophrenia due to its high risk of life-threatening side effects. The most significant adverse reaction is agranulocytosis, a severe reduction in granulocytes that leaves the client highly susceptible to overwhelming sepsis and necessitates strict, federally mandated hematologic monitoring. A. Uric acid levels are typically monitored in conditions such as gout or during the initiation of chemotherapy for certain leukemias to prevent tumor lysis syndrome. Clozapine does not significantly affect purine metabolism or renal excretion of uric acid, making this test unnecessary for the standard monitoring of this medication. B. Platelet counts are essential for monitoring coagulation disorders or medication-induced thrombocytopenia. While clozapine can rarely affect other blood cell lines, its primary and most dangerous hematological effect is on the white cell lineage, particularly neutrophils, rather than the thrombocytes responsible for primary hemostatic plug formation. C. Fasting blood glucose is an important longitudinal monitor for clients on clozapine due to the risk of metabolic syndrome and new-onset diabetes mellitus. However, glucose monitoring is typically performed at baseline, at 12 weeks, and then annually, rather than on the intensive weekly schedule required for hematologic safety. D. WBC count and absolute neutrophil count (ANC) must be monitored weekly for the first 6 months of clozapine therapy. This rigorous schedule is designed to detect early signs of bone marrow suppression. If the WBC falls below 3,000/mm3 or the ANC falls below 1,500/mm3, the medication must be immediately discontinued to prevent fatal infection.