A 68-year-old woman with CKD stage 4 (eGFR 22 mL/min/1.73m²) has serum potassium 6.2 mEq/L. She is on lisinopril, amlodipine, and furosemide. ECG shows peaked T waves. Which is the first drug given for cardiac membrane stabilisation?
- A Sodium bicarbonate IV
- B Regular insulin 10 units IV with dextrose
- C Calcium gluconate 10% IV ✓
- D Sodium polystyrene sulphonate (Kayexalate) orally
Correct answer: C. Calcium gluconate 10% IV
Explanation
In hyperkalaemia with ECG changes, the immediate priority is cardiac membrane stabilisation with intravenous calcium gluconate (10 mL of 10% solution over 2–3 minutes), which antagonises the membrane effects of hyperkalaemia within 1–3 minutes. It does not lower serum potassium. Insulin-dextrose and sodium bicarbonate shift K⁺ intracellularly (slower onset 15–30 min). Kayexalate eliminates K⁺ over hours and is not suitable for emergencies.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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