A 2-year-old child with severe acute malnutrition (SAM) is admitted with bilateral pitting pedal edema, skin lesions, and a miserable affect. Weight-for-height is -3 SD. On day 2 of treatment with F-75, the child develops bradycardia, prolonged QT interval on ECG, and muscle weakness. Which electrolyte abnormality is MOST responsible?
- A Hypokalemia ✓
- B Hyponatremia
- C Hypocalcemia
- D Hypermagnesemia
Correct answer: A. Hypokalemia
Explanation
Children with SAM (kwashiorkor type) have profound whole-body potassium depletion despite potentially normal or low serum K+. During refeeding, glucose and insulin drive potassium intracellularly, precipitating severe hypokalemia — the refeeding syndrome. Hypokalemia causes prolonged QT, ventricular arrhythmias, bradycardia, and muscle weakness. F-75 formula used in the stabilization phase is designed to be low in sodium but is potassium-supplemented to prevent this. Hyponatremia (dilutional) is common in kwashiorkor but does not primarily explain QT prolongation and bradycardia.
Reference: Ghai Essential Pediatrics, 10th ed.
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