A 50-year-old man with CKD stage 4 (eGFR 22 mL/min) presents with serum potassium 6.8 mEq/L and ECG changes including peaked T waves and a widened QRS (0.14 s). Blood pressure is 130/80 mmHg. The immediate priority treatment that shifts potassium intracellularly fastest is:

• A IV calcium gluconate 10 mL of 10% solution
• B Sodium polystyrene sulfonate (Kayexalate) oral
• C Sodium bicarbonate IV infusion
• D IV insulin 10 units plus 50 mL of 50% dextrose ✓

Explanation

In severe symptomatic hyperkalaemia with ECG changes, IV calcium gluconate is given first (within minutes) to stabilise the cardiac membrane — this is membrane stabilisation, not potassium shifting. Insulin with dextrose acts within 15–30 minutes to shift potassium intracellularly and is the fastest potassium-shifting intervention. The question specifically asks about the fastest intracellular shift. Calcium acts on membranes without lowering potassium. Bicarbonate shifts K+ but is slower and less reliable in non-acidaemic patients.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.