The nurse practitioner is reviewing laboratory results for a 65-year-old man with a history of diabetes mellitus and heart failure. His most recent potassium (K⁺) level is 5.5 mEq/L. Which of the following is the next appropriate step?

Choice A reason: A potassium level of 5.5 mEq/L is mildly elevated and not within the normal range. Doing nothing would be inappropriate, especially in a patient with heart failure, where hyperkalemia can precipitate arrhythmias. Choice B reason: Immediate hospital admission is not warranted for a potassium level of 5.5 mEq/L unless there are ECG changes or symptoms of hyperkalemia. This step would be premature without further assessment. Choice C reason: IV fluids are not the first-line treatment for mild hyperkalemia unless there is volume depletion or renal impairment. Rechecking potassium without assessing cardiac status could miss potentially dangerous arrhythmias. Choice D reason: An electrocardiogram (ECG) is the appropriate next step to assess for cardiac effects of hyperkalemia. ECG changes such as peaked T waves or widened QRS complexes would guide further management, including possible hospital admission or urgent treatment. This approach balances safety and clinical judgment.