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The symptoms of the refeeding syndrome are thought to be due predominantly to hypophosphataemia, but metabolic changes in potassium, magnesium, glucose, and thiamine can also contribute.

About

• May occur when patients have the reintroduction of feeding parenterally or enterally following a period of starvation with carbohydrates.
• Remember patients with normal prefeeding levels of potassium, magnesium and phosphate can still be at risk of refeeding syndrome
• Occurs within the first few days after Refeeding

Aetiology

• Is mostly due to a fall in phosphate caused by a rise in Insulin
• Fat has been used as an energy source during starvation
• Refeeding means that there is a switch to carbohydrate
• There is a corresponding rise in Insulin

Key factors

• Glucose: Glucose causes a rise in Insulin and phosphate; magnesium and potassium enter cells worsening plasma levels
• Low Magnesium, Phosphate, Potassium: causes arrhythmias, the muscle weakens, rhabdomyolysis
• Vitamins (thiamine): Wernicke Korsakoff, muscle weakness
• Fluid & sodium: Fluids and sodium can precipitate CCF

Risk Groups

• Anorexia nervosa, alcoholism and malignancy
• Post GI surgery or any form of prolonged starvation 7-10 days
• Patients undergoing chaemotherapy, Low BMI to start
• Chronic vomiting (hyperemesis gravidarum)
• Prolonged diarrhoea, gastrointestinal obstruction
• Malabsorption diseases, and poorly controlled diabetes

Very High Risk: Patient has one or more of the following:

• BMI < 14 kg/m²
• Negligible intake for > 15 days
• Pre feeding Low K/Phosphate/Mg

Clinical

• Muscle weakness, Rhabdomyolysis, Respiratory failure
• Cardiogenic shock, Haemolysis - anaemia, Thrombocytopenia - purpura
• Seizures and sudden death and arrhythmias

Investigations

• Weight, height, BMI, U&E and Glucose,
• Calcium, ALP, Phosphate < 0.5 mmol/L

Management

• Restart nutrition slowly with 10 Kcal/kg to normal levels in 4-7 days. Even lower levels in those at very high risk.
• Consider restoring circulatory volume and monitoring fluid balance and overall clinical status closely
• Oral Thiamine 200-300 mg /day or Pabrinex
• Treat with IV/Oral phosphate supplementation: IV forms are Addiphos, polyfusor. Oral Phosphate sandoz, potassium acid. Give Phosphate 0.3-0.6 mmol/kg/day
• Potassium 2-4 mmol/kg/day adjusted to serum levels. Oral Potassium chloride Sando K, Slow K, KayCeeL, IV 2-4 mmol/kg/day
• Magnesium IV if needed: Magnesium Sulphate Magnaspartate sachets, Magnesium oxide or glycerophosphate 0.2 mmol/kg/day intravenous to 0.4 mmol/kg/day oral
• Daily monitoring of phosphate levels as well as U&E, Creatinine, FBC, Mg, Zn, Ca
• IV Pabrinex daily for 5 days and slow reintroduction of calories