Final answer:
The nurse should prioritize notifying the provider if the client taking clozapine experiences agranulocytosis, a potentially life-threatening condition characterized by a severe decrease in white blood cell count. This rare but serious side effect of clozapine requires immediate medical attention.
Step-by-step explanation:
The nurse should prioritize notifying the provider if the client taking clozapine experiences agranulocytosis. Agranulocytosis is a potentially life-threatening condition characterized by a severe decrease in white blood cell count, specifically neutrophils. This condition is a rare but serious side effect of clozapine that requires immediate medical attention. The nurse should inform the provider so that appropriate interventions can be implemented, such as discontinuing or adjusting the medication.