A nurse is caring for a client who has hypertension and has a potassium level of 6.8 mEq/L. Which of the following actions should the nurse take?

A. Obtain a blood sample for a serum sodium level Not directly related to the immediate issue of hyperkalemia. B. Advise the client to add citrus juices and bananas These are high in potassium and should be avoided in hyperkalemia. C. Suggest salt substitutes Many salt substitutes contain potassium-contraindicated in hyperkalemia. D. Obtain a 12-lead ECG Hyperkalemia affects cardiac conduction-immediate ECG monitoring is critical.