In a patient with chronic kidney disease presenting with severe hyperkalemia, after initial fluid resuscitation what is the most important next step?

• A. Insulin
• B. Sodium bicarbonate
• C. Calcium gluconate
• D. Kayexalate

Answer: (C)

The immediate priority in severe hyperkalemia is protecting the heart. Calcium gluconate stabilizes the cardiac cell membranes, reducing the risk of dangerous arrhythmias as you work to lower the potassium. It does not lower potassium itself, but it buys time to implement other measures. After membrane stabilization, you would shift potassium into cells (for example, with insulin and glucose, and sometimes bicarbonate if there is acidosis) and then remove potassium (with dialysis in CKD, or other means). Kayexalate is slower and not suitable for emergent management. So calcium gluconate is the best next step after fluids.