In hyperkalemia with ECG changes, what is the first-line therapy to protect the heart?

• A. Insulin with dextrose
• B. Calcium to protect the heart
• C. Sodium bicarbonate alone
• D. Dialysis

Answer: (B)

When potassium is elevated and the ECG shows changes, the immediate priority is to stabilize the heart and prevent arrhythmias. Calcium acts as a membrane stabilizer for cardiac myocytes by increasing the threshold potential, which reduces excitability and protects against the dangerous electrical effects of hyperkalemia. This stabilizing effect happens quickly, buying time for other treatments that actually lower the potassium or move it into cells to take effect. While insulin with glucose, bicarbonate, or dialysis can lower serum potassium or remove it from the body, they do not provide the immediate heart-protective effect that calcium offers. So the first-line move is to give calcium to protect the heart.