Final answer:
The lab values that indicate a need to discontinue treatment with clozapine in a client with schizophrenia are a WBC count less than 1800 and an ANC less than 1200.
Step-by-step explanation:
The lab values that indicate a need to discontinue treatment with clozapine in a client with schizophrenia are a white blood cell (WBC) count less than 1800 and an absolute neutrophil count (ANC) less than 1200. A low WBC count can indicate bone marrow suppression, which is a serious adverse effect of clozapine. Similarly, a low ANC indicates a decrease in the number of neutrophils, which are important for fighting infections.