A 3-year-old child with severe acute malnutrition is started on intensive milk-based feeding on admission. On day 3 he becomes lethargic, develops paraesthesiae around the mouth, and shows a broad complex arrhythmia on monitoring. Serum phosphorus is 1.1 mg/dL. The most likely mechanism underlying this complication is:

• A Insulin-mediated intracellular shift of phosphate following carbohydrate load ✓
• B Renal phosphate wasting secondary to osmotic diuresis
• C Impaired renal tubular reabsorption from sepsis-induced tubular injury
• D Reduced intestinal phosphate absorption due to pancreatic enzyme deficiency

Explanation

Refeeding syndrome occurs when rapid carbohydrate feeding in a starved, chronically malnourished subject triggers a surge of insulin, driving phosphate, potassium, magnesium, and thiamine into cells. Hypophosphataemia impairs ATP generation and membrane function, causing weakness, paraesthesiae, arrhythmia, and respiratory failure. Renal wasting and absorption defects do not fit the abrupt onset within days of initiating feed. Prevention lies in slow initiation of feeds with careful electrolyte correction.

Reference: WHO Pocket Book of Hospital Care for Children and Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.