A 55-year-old man with a history of chronic kidney disease presents with generalized weakness and fatigue. An electrocardiogram (ECG) shows tall, peaked T waves. Laboratory results reveal a serum potassium level of 7.2 mEq/L. What is the most important immediate intervention to stabilize the cardiac membrane?

The correct answer to the question "A 55-year-old man with a history of chronic kidney disease presents with generalized weakness and fatigue. An electrocardiogram (ECG) shows tall, peaked T waves. Laboratory results reveal a serum potassium level of 7.2 mEq/L. What is the most important immediate intervention to stabilize the cardiac membrane?" is Option C: Intravenous calcium gluconate.

The other options — A) Intravenous insulin and dextrose, B) Sodium polystyrene sulfonate (Kayexalate), D) Intravenous furosemide — are incorrect for this USMLE Exam Prep question. As explained above: In severe hyperkalemia with ECG changes (like peaked T waves), intravenous calcium gluconate is the immediate priority. It directly stabilizes the cardiac membrane, reducing the risk of arrhythmias, …