In the initial management of hyperkalemia with ECG changes, which intervention stabilizes cardiac membranes?

• A. Administer insulin and glucose
• B. Administer sodium bicarbonate
• C. Administer calcium gluconate
• D. Administer potassium-binding resin

Answer: (C)

Calcium stabilizes the heart’s electrical membranes in hyperkalemia. When potassium is high, the resting membrane potential becomes less negative, which disrupts sodium channel function and speeds or worsens conduction, raising the risk of dangerous arrhythmias. Giving calcium IV increases the threshold for depolarization and stabilizes myocardial membranes, reducing excitability and protecting the myocardium quickly—usually within minutes. Crucially, this intervention does not lower the potassium level itself; it simply shields the heart while other treatments are used to shift potassium into cells or remove it from the body. After membrane stabilization, measures such as insulin with glucose, bicarbonate if acidosis is present, beta-agonists, or potassium-binding therapies and dialysis can be employed to reduce the serum potassium concentration.