A 52-year-old man with chronic kidney disease (eGFR 18 mL/min/1.73m²) and diabetic nephropathy presents to the emergency department with severe hyperkalemia (K⁺ 7.2 mEq/L) and peaked T waves on ECG. Which drug should be administered first to shift potassium intracellularly?

Explanation

## Management of Severe Hyperkalemia with ECG Changes **Key Point:** Insulin with dextrose is the first-line agent to shift potassium intracellularly in symptomatic or ECG-positive hyperkalemia because it acts rapidly (within 10–20 minutes) and reliably. ### Mechanism of Action Insulin drives K⁺ into cells via Na⁺-K⁺-ATPase activation. Dextrose (glucose) is co-administered to prevent hypoglycemia and enhance the shift. This is a **transcellular shift** — it does not remove potassium from the body but buys time for definitive removal. ### Why Insulin + Dextrose is First-Line - Onset: 10–20 minutes - Duration: 4–6 hours - Efficacy: Reduces K⁺ by 0.5–1.2 mEq/L - Works in all renal function states - Safe in diabetics (glucose co-administered) ### Typical Dosing - **Insulin:** 10 units IV regular insulin - **Dextrose:** 25 g IV (50 mL of 50% dextrose) or 100 mL of 25% dextrose - Monitor blood glucose; recheck K⁺ at 30 min, 1 hr, 4 hr ### Concurrent Therapies While insulin + dextrose acts, initiate **potassium removal**: - Diuretics (furosemide) if euvolemic or hypervolemic - Cation exchange resin (sodium polystyrene sulfonate) — slower onset (2–4 hrs), used for chronic management - Dialysis if K⁺ > 6.5 mEq/L + renal failure or refractory to medical therapy **High-Yield:** In acute symptomatic hyperkalemia with ECG changes, **insulin + dextrose** or **insulin + beta-2 agonist (salbutamol)** are the fastest transcellular shift agents. Insulin + dextrose is preferred in most settings because it is more predictable. **Clinical Pearl:** Calcium gluconate (10 mL of 10% solution IV over 2–5 min) should be given **simultaneously** if ECG changes are present — it stabilizes the myocardium but does NOT lower K⁺. It buys time while insulin acts. **Warning:** Do NOT rely on sodium polystyrene sulfonate or furosemide alone in acute ECG-positive hyperkalemia — they are too slow. Sodium bicarbonate is second-line (useful in metabolic acidosis) and less reliable than insulin.