What is refeeding syndrome?

Refeeding Syndrome: Definition, Pathophysiology, and Management

Refeeding syndrome is a potentially fatal condition characterized by severe fluid and electrolyte shifts that occurs when nutrition is reintroduced too rapidly in malnourished patients, leading to cardiac, neurological, and hematological complications. 1

Definition and Pathophysiology

Refeeding syndrome (RS) is defined as a severe disruption in electrolyte and fluid balance that occurs when feeding (whether oral, enteral, or parenteral) is begun too aggressively after a period of inadequate nutrition. This syndrome results from feeding-induced hormonal and metabolic derangements that can cause serious clinical complications 1.

The key pathophysiological features include:

• Electrolyte disturbances: Primarily hypophosphatemia, often accompanied by hypokalemia and hypomagnesemia
• Fluid imbalance: Typically presenting as fluid retention and peripheral edema
• Metabolic changes: Including disturbed glucose homeostasis and hyperlactatemia
• Vitamin deficiencies: Particularly thiamine (vitamin B1) deficiency

Clinical Manifestations

RS can manifest with various clinical symptoms and complications:

• Cardiovascular: Heart failure, arrhythmias, sudden cardiac death (reported in up to 20% of cases) 1
• Neurological: Delirium, encephalopathy, seizures
• Respiratory: Respiratory failure, difficulty weaning from ventilation
• Neuromuscular: Muscle weakness, rhabdomyolysis
• Hematological: Anemia, thrombocytopenia
• Other: Organ dysfunction, potentially leading to multi-organ failure

High-Risk Patients

Patients at highest risk for developing RS include those with:

• BMI <16 kg/m² 1
• Unintentional weight loss >15% in 3-6 months 1
• Little or no nutritional intake for >10 days 1
• Low baseline levels of potassium, phosphate, or magnesium 1
• History of:
  • Chronic alcoholism
  • Anorexia nervosa
  • Severe chronic malnutrition
  • Prolonged fasting
  • Bariatric surgery
  • Drug abuse (particularly insulin, antacids, diuretics) 1

Moderate risk factors include:

• BMI <18.5 kg/m² 1
• Weight loss >10% in 3-6 months 1
• Little or no nutritional intake for >5 days 1

Prevention and Management

Prevention

1. Identify at-risk patients through nutritional screening upon admission to healthcare facilities 1

2. Start nutrition cautiously:

   • For patients with minimal food intake for at least 5 days: Begin with no more than 50% of calculated energy requirements for the first 2 days 1
   • For severely depleted patients: Initial energy supply should not exceed 5-10 kcal/kg/day 1
   • Gradually increase over 4-7 days until full nutritional requirements are met 1

3. Prophylactic supplementation:

   • Thiamine: 200-300 mg daily before and during nutritional repletion 1
   • Balanced micronutrient mixture 1

4. Close monitoring:

   • Electrolytes (phosphate, potassium, magnesium)
   • Fluid balance
   • Cardiac function (heart rate, rhythm)
   • Clinical status 1

Treatment

If RS develops, management includes:

1. Electrolyte replacement:

   • Potassium: 2-4 mmol/kg/day 1
   • Phosphate: 0.3-0.6 mmol/kg/day 1
   • Magnesium: 0.2 mmol/kg/day IV or 0.4 mmol/kg/day orally 1

2. Adjust feeding rate: Slow down or temporarily halt nutritional support if severe electrolyte abnormalities occur

3. Cardiac monitoring: Particularly in severe cases with significant electrolyte disturbances

4. Treat complications as they arise (e.g., heart failure, respiratory distress)

Clinical Impact

Recent research indicates that RS is common and significantly impacts clinical outcomes:

• Increased length of hospital stay (12.5 days vs. 7.1 days for patients without RS) 2
• Higher mortality rates 2
• Early medical nutritional support (within 48 hours) may reduce mortality in at-risk patients 2

Common Pitfalls

1. Failure to identify at-risk patients - Always screen for malnutrition risk factors upon admission

2. Overly aggressive refeeding - The desire to rapidly correct malnutrition must be balanced against the risk of RS

3. Inadequate monitoring - Electrolytes should be checked frequently (daily initially) in high-risk patients

4. Overlooking thiamine supplementation - Must be given before carbohydrate administration to prevent Wernicke's encephalopathy

5. Assuming RS only occurs with parenteral nutrition - RS can develop with any form of nutritional repletion, including oral feeding 3, 4

By identifying at-risk patients and implementing appropriate preventive measures, the potentially fatal complications of refeeding syndrome can be avoided while successfully rehabilitating malnourished patients.