A 45-year-old man with sepsis secondary to pneumonia develops acute kidney injury with oliguria (urine output 300 mL/day), rising creatinine (2.5 mg/dL), and severe hyperkalemia (K⁺ 6.8 mEq/L). After initial stabilization with fluid resuscitation and antibiotics, what is the drug of choice for acute management of hyperkalemia in this setting?

Explanation

## Acute Hyperkalemia Management in AKI **Key Point:** Insulin with dextrose is the drug of choice for **immediate, life-threatening hyperkalemia** because it rapidly shifts potassium intracellularly within 10–20 minutes, providing the fastest reduction in serum K⁺. ### Mechanism of Insulin + Dextrose 1. Insulin stimulates Na⁺-K⁺-ATPase pump activity 2. K⁺ is driven intracellularly in exchange for Na⁺ 3. Dextrose prevents hypoglycemia and enhances insulin secretion 4. **Onset:** 10–20 minutes; **Duration:** 4–6 hours ### Dosing - **Insulin (regular):** 10 units IV bolus - **Dextrose:** 25 g IV (50 mL of 50% dextrose) or 100 mL of 25% dextrose - Can repeat every 15–30 minutes if needed - Monitor blood glucose; risk of rebound hyperglycemia **High-Yield:** In septic AKI with severe hyperkalemia (K⁺ >6.5 mEq/L), insulin + dextrose is the **fastest pharmacological intervention** while preparing for dialysis or other definitive measures. ### Comparison of Hyperkalemia Agents | Agent | Onset | Duration | Mechanism | Use in AKI | |-------|-------|----------|-----------|------------| | **Insulin + Dextrose** | 10–20 min | 4–6 hrs | K⁺ shift intracellular | **FIRST-LINE for acute, severe** | | Sodium polystyrene sulfonate | 2–12 hrs | 4–24 hrs | GI K⁺ binding & excretion | Chronic/mild; too slow for acute | | Spironolactone | Days | Weeks | K⁺-sparing diuretic | **CONTRAINDICATED in AKI** (worsens K⁺) | | Amiloride | Days | Weeks | K⁺-sparing diuretic | **CONTRAINDICATED in AKI** (worsens K⁺) | **Clinical Pearl:** In oligoanuric AKI (urine output <300 mL/day), **potassium-sparing agents are absolutely contraindicated** because the kidney cannot excrete potassium. Insulin + dextrose buys time for dialysis initiation. **Mnemonic: SHIFT** — **S**odium polystyrene (slow), **H**yperventilation (respiratory alkalosis), **I**nsulin + dextrose (fast), **F**luoride (calcium gluconate — cardiac membrane stabilizer), **T**ransfusion (RBC transfusion increases K⁺ load — avoid if possible). **Warning:** Do not use potassium-sparing diuretics (spironolactone, amiloride) in AKI — they block renal K⁺ excretion and **worsen hyperkalemia**. These are appropriate only in chronic kidney disease with preserved urine output.