A 60-year-old male with acute renal failure following iodinated contrast CT has peaked T-waves and widened QRS complexes on ECG. Serum potassium is 7.2 mEq/L. What is the immediate first drug to administer?

Answer and explanation

Correct answer: D. Intravenous calcium gluconate

  1. Step 1: Severe hyperkalemia with ECG changes (peaked T waves, broadened QRS, loss of P waves) is a medical emergency with imminent risk of ventricular fibrillation or asystole.
  2. Step 2: The immediate first step is intravenous calcium gluconate (10 mL of 10% solution over 2-3 minutes) to stabilize cardiac myocyte membranes against depolarization.
  3. Step 3: Calcium does not lower serum potassium; subsequent agents (insulin/glucose, salbutamol) are given to shift potassium intracellularly.
Answer
Intravenous calcium gluconate.
Why not the others: 'Insulin with 50% dextrose infusion' shifts potassium into cells but takes 15-30 minutes to work; 'Sodium polystyrene sulfonate orally' removes potassium slowly over hours via GI excretion; 'Intravenous furosemide' promotes urinary potassium loss but is ineffective in anuric acute renal failure.

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