Refeeding syndrome

Refeeding syndrome

Introduction

Refeeding syndrome is a life-threatening metabolic disturbance that occurs when nutritional support is reintroduced too rapidly to severely malnourished individuals. It is characterised by shifts in fluids and electrolytes, especially phosphate, potassium, and magnesium, leading to multi-organ dysfunction.

Peak Incidence

  • Bimodal peak:
    • 15–35 years – Often due to eating disorders (e.g. anorexia nervosa).
    • Over 60 years – Often due to frailty, chronic illness, or malnutrition (e.g. cancer, dementia, alcoholism).

Pathophysiology

  • In malnutrition, the body adapts to a catabolic state with low insulin levels.
  • Upon reintroduction of carbohydrates, insulin secretion rises, causing:
    • Intracellular shift of phosphate, potassium, and magnesium.
    • Rapid glucose uptake.
    • Increased ATP production, further depleting phosphate.
  • The resulting hypophosphataemia impairs oxygen delivery, cellular function, and muscle activity, while hypokalaemia and hypomagnesaemia cause arrhythmias, neuromuscular dysfunction, and seizures.

Symptoms

Hypophosphataemia

  • Muscle weakness.
  • Respiratory failure – Due to diaphragmatic and accessory muscle weakness.
  • Cardiac dysfunction – Heart failure, arrhythmias.
  • Confusion, seizures, coma.
  • Rhabdomyolysis.
  • Haemolysis.

Hypokalaemia

  • Muscle weakness and cramps.
  • Life-threatening arrhythmias.

Hypomagnesaemia

  • Paraesthesia.
  • Tetany.
  • Seizures.
  • Arrhythmias (e.g. torsades de pointes).

Signs

  • Neurological – Confusion, ataxia, seizures, encephalopathy.
  • Cardiovascular – Tachycardia, hypotension, arrhythmias, oedema.
  • Gastrointestinal – Bloating, nausea, early satiety.
  • Musculoskeletal – Muscle weakness, rhabdomyolysis.
  • Haematological – Haemolytic anaemia.

Diagnosis

Biochemical Findings

  • Hypophosphataemia – Most characteristic.
  • Hypokalaemia.
  • Hypomagnesaemia.
  • Hyperglycaemia may occur during refeeding.

NICE Criteria for Risk Stratification

High Risk (if one or more of the following):

  • BMI <16 kg/m².
  • Unintentional weight loss >15% in 3–6 months.
  • No nutritional intake for >10 days.
  • Pre-existing low potassium, phosphate, or magnesium.

Moderate Risk (if two or more of the following):

  • BMI <18.5 kg/m².
  • Weight loss >10% in 3–6 months.
  • No nutritional intake for >5 days.
  • History of alcohol misuse or use of insulin, chemotherapy, antacids, or diuretics.

Complications

  • Cardiac arrhythmias, especially torsades de pointes.
  • Respiratory failure – Due to respiratory muscle weakness.
  • Severe electrolyte imbalance – Leading to seizures, coma.
  • Rhabdomyolysis.
  • Haemolysis.
  • Acute heart failure and shock.
  • Wernicke encephalopathy – Especially in patients with alcohol misuse or thiamine deficiency.

Management

Pre-Feeding Assessment

  • Identify at-risk patients using NICE criteria.
  • Admit to hospital for close monitoring if high risk.
  • Administer IV thiamine (e.g. 200–300 mg/day) for 3–5 days before and during refeeding to prevent Wernicke encephalopathy.

Nutritional Reintroduction

  • Start at ≤50% of energy requirements for the first 1–2 days (lower in very high-risk patients).
  • Gradually increase over 5–10 days based on tolerance and biochemical stability.
  • Can be oral, enteral, or parenteral depending on clinical context.

Electrolyte Replacement

  • Monitor phosphate, potassium, magnesium, and calcium at least daily initially.
  • Replace as required, typically via IV supplementation:
    • IV phosphate (e.g. sodium glycerophosphate).
    • IV potassium chloride (under cardiac monitoring if high dose).
    • IV magnesium sulphate.

Other Supportive Measures

  • Monitor blood glucose and treat hyperglycaemia if needed.
  • Correct fluid balance cautiously to avoid overload.
  • Monitor ECG and vital signs.

Specialist Involvement

  • Early involvement of a dietitian is essential.

    • For calculating energy needs.
    • Guiding refeeding rate and micronutrient supplementation.

  • Consider ICU referral for patients with:

    • Arrhythmias.
    • Respiratory failure.
    • Profound biochemical abnormalities.

FAQ from our users

What is the pathophysiology of refeeding syndrome?
  • Starvation State (Prolonged Malnutrition):
    • During prolonged malnutrition, the body adapts by using fat and protein for energy due to depleted glycogen stores.
    • Insulin levels decrease, and metabolic shifts occur, such as reduced glucose and insulin secretion.
  • Refeeding Phase (Introduction of Nutrition):
    • Reintroduction of carbohydrates increases blood glucose levels, leading to insulin secretion.
  • Insulin Effects and Electrolyte Shifts:
    • Insulin drives potassium (K+), phosphate (PO4), and magnesium (Mg2+) into cells, depleting their blood levels and leading to hypophosphatemia, hypokalaemia, and hypomagnesemia.
    • This results in significant electrolyte disturbances, which can trigger muscle weakness, cardiac arrhythmias, respiratory dysfunction, seizures, and confusion.
Which patients are at a higher risk for developing refeeding syndrome ?
  • Protein-energy malnutrition
  • Anorexia nervosa and other eating disorders
  • Chronic alcoholism
  • Prolonged fasting or starvation
  • Critical illness or major surgeries

Common pitfalls in a clinical setting

Common pitfalls in a clinical setting
  • According to NICE, refeeding syndrome is more common in patients receiving enteral tube feeding or parenteral nutrition, but is possible with oral refeeding. Dietician input is important.
  • Phosphorus deficiency is the most common feature of refeeding syndrome.
  • The MUST score (Malnutrition Universal Screening Tool) is critical and should be calculated for every patient admitted to the hospital
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