Nutrition and metabolic support

Refeeding syndrome

Reviewed Nov 2026·2 references
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Identify risk, start feeds low with thiamine, monitor phosphate, potassium and magnesium, and restrict calories if phosphate falls.

Definition
Refeeding syndrome: electrolyte shifts (hypophosphataemia, hypokalaemia, hypomagnesaemia) and thiamine deficiency after starting nutrition in a starved patient, causing organ dysfunction (respiratory failure, arrhythmia, heart failure, delirium) usually within 72 h (ASPEN: fall in phosphate, K or Mg by 10-20% mild, 20-30% moderate, > 30% or organ dysfunction severe).

At the bedside

  1. 1

    Identify risk

    BMI < 16-18.5, weight loss > 5-15% in 1-6 months, little or no intake for > 5-10 days, low K/PO4/Mg before feeding, alcohol use disorder, chronic illness, cancer, eating disorders.

  2. 2

    Thiamine first

    Before feeds

    Thiamine 100 mg before feeding and daily for 5-7 days.

  3. 3

    Start low

    10-20 kcal/kg for first 24 h, advance by 33% of goal every 1-2 days; correct electrolytes before and during (do not delay feeding solely to correct them).

  4. 4

    Monitor

    Phosphate, K, Mg every 12 h for 3 days in high-risk patients, then daily; fluid balance, heart rate, glucose.

  5. 5

    If phosphate falls

    Phosphate < 2 mg/dL (0.65 mmol/L) or falls > 30% after starting feeds: reduce energy intake (REFEED: restrict to ~20 kcal/h for 2 days, then increase gradually) and replace phosphate.

  6. 6

    Replace

    IV phosphate 0.16-0.64 mmol/kg depending on severity; K and Mg as needed.

Refeeding prevention

Thiamine

IV/oral
Dose
100 mg before feeds, then daily for 5-7 days

Moderate hypophosphataemia (1-1.9 mg/dL)

Phosphate replacement (potassium or sodium phosphate)

IV
Dose
0.16-0.32 mmol/kg over 4-6 h
Worked example
70 kg: 11-22 mmol phosphate in 250 mL NS over 6 h
Red flag · call your senior now
New respiratory muscle weakness, failed weaning, arrhythmia or confusion 2-3 days after starting feeds: check phosphate.
Pitfall
Starting full feeds in a starved alcoholic patient without thiamine and electrolyte monitoring.
Pearl
Hypophosphataemia in ventilated patients delays weaning and impairs diaphragm function - check phosphate before SBTs.

References

  1. 1

    da Silva JSV, Seres DS, Sabino K, et al. ASPEN consensus recommendations for refeeding syndrome. Nutr Clin Pract 2020;35:178-95.

  2. 2

    Doig GS, Simpson F, Heighes PT, et al. Restricted versus continued standard caloric intake during the management of refeeding syndrome in critically ill adults: a randomised, parallel-group, multicentre, single-blind controlled trial. Lancet Respir Med 2015;3:943-52.

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