Makindo Medical Notes

Related Subjects: |Malnutrition universal screening tool (MUST) |Body Mass Index |Peripherally inserted central catheters (PICC) |Refeeding syndrome |Marasmus

The hallmark of refeeding syndrome is severe hypophosphataemia, although abnormalities in potassium, magnesium, glucose, and thiamine also contribute significantly to the clinical presentation and complications.

About

• Refeeding syndrome can occur upon reintroducing carbohydrates (enterally or parenterally) after a prolonged period of starvation or inadequate intake.
• Patients with normal pre-feeding levels of potassium, magnesium, and phosphate can still develop refeeding syndrome.
• The condition typically manifests within the first few days of refeeding.

Pathophysiology & Aetiology

• Insulin Surge: Transition from fat-based metabolism (during starvation) to carbohydrate metabolism drives insulin release.
• Intracellular Shift: Insulin promotes cellular uptake of phosphate, potassium, and magnesium, lowering their plasma levels.
• Starvation State: Body relies on fat/protein catabolism; once carbohydrate is reintroduced, the abrupt metabolic shift can cause sudden depletion of serum electrolytes.

Key Metabolic Changes

• Glucose & Insulin: Rising insulin causes phosphate, magnesium, and potassium to move intracellularly → worsens plasma electrolyte levels.
• Electrolyte Depletion:
  • Low phosphate, potassium, and magnesium can lead to arrhythmias, muscle weakness, and rhabdomyolysis.
• Thiamine Deficiency: May precipitate or worsen Wernicke–Korsakoff syndrome and muscle weakness.
• Fluid & Sodium Balance: Reintroduction of fluid and sodium can precipitate fluid overload, heart failure, or pulmonary oedema.

High-Risk Groups

• Anorexia nervosa, alcoholism, and malignancy
• Prolonged fasting (≥7–10 days), chronic GI conditions (vomiting, diarrhoea, obstruction)
• Malabsorption syndromes, low BMI, or receiving chemotherapy
• Hyperemesis gravidarum
• Poorly controlled diabetes with ketoacidosis (prolonged catabolic state)

Very High-Risk Criteria

• BMI <14 kg/m²
• Minimal or no intake for >15 days
• Pre-feeding hypokalaemia, hypophosphataemia, and/or hypomagnesaemia

Clinical Features

• Muscle weakness, rhabdomyolysis, respiratory failure
• Cardiogenic shock, arrhythmias, haemolysis, thrombocytopenia
• Seizures, sudden death in severe cases

Investigations

• Nutritional Assessment: Weight, height, BMI
• Blood Tests: U&E, glucose, calcium, ALP, phosphate (notable if <0.5 mmol/L), magnesium, potassium
• Monitor closely for electrolyte shifts once feeding is initiated

Management

• Slow Refeeding: Initiate at ~10 kcal/kg/day (or even lower in very high-risk patients), then gradually increase to target over 4–7 days.
• Fluid & Electrolyte Management: Correct volume status, track input/output, and monitor for fluid overload.
• Thiamine Supplementation:
  • Oral thiamine 200–300 mg/day or IV Pabrinex to prevent Wernicke–Korsakoff syndrome.
• Phosphate Replacement:
  • IV (e.g., Addiphos) or oral (e.g., Phosphate Sandoz) to provide 0.3–0.6 mmol/kg/day, adjusted by serum levels.
• Potassium Replacement:
  • 2–4 mmol/kg/day (oral supplements like Sando K or Slow K, or IV if required).
• Magnesium Replacement:
  • IV magnesium sulphate or oral magnesium salts (e.g., Magnaspartate) 0.2–0.4 mmol/kg/day, as needed based on labs.
• Daily Monitoring:
  • Check serum electrolytes (phosphate, potassium, magnesium), U&E, creatinine, FBC, calcium, and zinc where appropriate.
  • Continue IV Pabrinex for up to 5 days if indicated.