What is the primary purpose of IV calcium gluconate in hyperkalemic emergencies?

• A. To rapidly shift potassium into cells
• B. To stabilize myocardial membranes and reduce excitability
• C. To inhibit potassium absorption in the gut
• D. To increase renal potassium excretion

Answer: (B)

When potassium is elevated, cardiac cells become more excitable, increasing the risk of dangerous arrhythmias. IV calcium gluconate rapidly stabilizes the heart by raising the threshold for depolarization and reducing myocardial excitability, effectively protecting the myocardium in the immediate crisis. This is a rapid, temporizing measure that does not lower the potassium level itself; it just shields the heart while other therapies remove or shift potassium from the body. Treatments that actually lower potassium work by moving potassium into cells or removing it from the body (for example, insulin with glucose or beta-agonists to shift potassium inward, bicarbonate in certain acid-base disorders, or diuretics/dialysis to excrete potassium). Calcium gluconate is used in this emergency context specifically for membrane stabilization and to prevent arrhythmias during the acute management.