A 60-year-old man with CKD stage 4 (eGFR 24 mL/min) has serum potassium of 6.2 mEq/L and is on ramipril. ECG shows peaked T waves. Which is the most appropriate IMMEDIATE step to stabilize the cardiac membrane?
- A Oral sodium polystyrene sulfonate (kayexalate)
- B IV sodium bicarbonate
- C IV 10% calcium gluconate ✓
- D Furosemide IV to promote kaliuresis
Correct answer: C. IV 10% calcium gluconate
Explanation
ECG changes (peaked T waves) indicate cardiac membrane instability from hyperkalemia. The most immediate treatment is IV calcium gluconate (10 mL of 10% solution over 2–3 minutes), which stabilizes the cardiac membrane by increasing the threshold potential, counteracting the depolarizing effect of hyperkalemia. It acts within minutes but does not lower potassium levels. Subsequent measures include insulin + dextrose (shift K+ intracellularly), sodium bicarbonate, salbutamol nebulization, and definitive removal with kayexalate, patiromer, or dialysis.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.