A 45-year-old man undergoes a major bowel resection. He is started on total parenteral nutrition (TPN) via a central venous catheter. On day 3, he becomes confused, develops tetany, and ECG shows a prolonged QT interval. Serum phosphate is 0.4 mmol/L (low). The most likely diagnosis is:

• A Hyperglycaemia from TPN glucose overload
• B Central venous catheter infection (CRBSI)
• C Refeeding syndrome ✓
• D Zinc deficiency from TPN

Explanation

Refeeding syndrome occurs when nutrition (enteral or parenteral) is restarted in malnourished or chronically starved patients. Insulin release from carbohydrate administration drives phosphate, potassium, and magnesium intracellularly, causing severe hypophosphataemia. Hypophosphataemia causes neurological symptoms (confusion, tetany), cardiac arrhythmias, and respiratory failure. NICE guidelines recommend starting nutrition at ≤10 kcal/kg/day in high-risk patients and monitoring/replacing electrolytes before and during refeeding.

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

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Written and medically reviewed by the StethoPrep medical team.