What is the mechanism by which IV calcium gluconate helps in hyperkalemia?

• A. Stabilizes myocardial membranes and reduces excitability
• B. Shifts potassium into cells
• C. Inhibits potassium absorption in the gut
• D. Increases renal potassium excretion

Answer: (A)

Calcium gluconate protects the heart by stabilizing cardiac cell membranes, reducing excitability in the setting of high potassium. When potassium is elevated outside the cells, the resting membrane potential becomes less negative, making cardiac tissue more prone to dangerous conduction abnormalities. Calcium raises the threshold for action potential initiation, so the heart becomes less excitable and less likely to develop arrhythmias. This effect is protective but does not lower the potassium level itself; other treatments are needed to shift potassium into cells or remove it from the body (such as insulin with glucose, beta-agonists, bicarbonate in acidosis, diuretics, or dialysis).