In a critically ill surgical patient requiring parenteral nutrition, refeeding syndrome is a potentially fatal complication. The metabolic hallmark and the electrolyte most critically depleted during refeeding syndrome is:

• A Hyperkalaemia due to intracellular potassium release
• B Hyponatraemia due to free water retention
• C Hypercalcaemia due to PTH suppression
• D Hypophosphataemia due to intracellular shift during glucose-stimulated insulin release ✓

Explanation

Refeeding syndrome occurs when carbohydrate reintroduction after prolonged starvation triggers insulin release, driving glucose, phosphate, potassium, and magnesium into cells. The cardinal feature is severe hypophosphataemia (serum phosphate <0.5 mmol/L), which impairs ATP and 2,3-DPG synthesis, causes haemolytic anaemia, respiratory muscle failure, cardiac arrhythmias, and seizures. NICE guidelines recommend supplementing phosphate, potassium, and magnesium before and during refeeding, with energy started at 10 kcal/kg/day in very high-risk patients.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.