A client is scheduled for a spiral computed tomography (CT) scan with contrast to evaluate for pulmonary embolism. Which information in the client's history requires follow-up by the nurse?

A. A metal hip prosthesis does not generally interfere with CT scans or contrast use. B. Metformin use requires follow-up because contrast agents can affect renal function, potentially increasing the risk of lactic acidosis in clients taking metformin. C. Sobriety is not directly relevant to the CT scan or contrast administration. D. The timing of a previous CT scan is not a concern unless it affects contrast use or renal function, which is not indicated here.