A nurse is caring for a client who is receiving an intravenous potassium infusion and who has a urine output of 10 mL/hr and a blood urea nitrogen of 50 mg/dL (10 to 20 mg/dL). Which of the following actions should the nurse take?

A. Obtain a prescription for furosemide: Administering a diuretic like furosemide could worsen hypovolemia or kidney injury if the client is already oliguric. It is not the first action when potassium is accumulating due to impaired renal excretion. B. Prepare the client for a urine culture and sensitivity: While a UTI could contribute to kidney dysfunction, the immediate concern is elevated potassium in the context of severely reduced urine output, making infection screening secondary. C. Discontinue the potassium infusion: The client has oliguria and elevated BUN, indicating impaired renal function. Continuing potassium infusion could lead to hyperkalemia and life-threatening cardiac complications. Stopping the infusion is the priority action to prevent toxicity. D. Perform a bladder scan: A bladder scan assesses for urinary retention, which could contribute to low urine output. However, the elevated BUN suggests intrinsic kidney impairment, making discontinuing potassium more urgent than assessing retention.