A 7-year-old in diabetic ketoacidosis has received 2 hours of IV fluids. Blood glucose is 380 mg/dL, serum potassium is now 4.6 mEq/L, ECG shows no potassium-related changes, and urine output is well established. The insulin infusion is running. What is the correct next step regarding potassium?
- A Withhold potassium until serum potassium falls below 3.5 mEq/L
- B Begin potassium replacement now, adding 40 mEq/L to the IV fluids ✓
- C Give a rapid IV push of potassium chloride over 5 minutes
- D Withhold all potassium until acidosis is fully corrected
Correct answer: B. Begin potassium replacement now, adding 40 mEq/L to the IV fluids
Explanation
Total body potassium is always depleted in DKA despite a normal or high initial serum value. Insulin drives potassium into cells and levels fall rapidly, so replacement begins once urine output is established and serum potassium is below approximately 5 mEq/L, typically 20 to 40 mEq/L added to fluids. Waiting for frank hypokalemia invites arrhythmia, and rapid IV push potassium is never given.
Reference: Nelson Textbook of Pediatrics, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.