What is refeeding syndrome?

Refeeding Syndrome

Refeeding syndrome is a severe disruption in electrolyte and fluid balance that occurs when nutrition is reintroduced too aggressively after a period of inadequate intake in malnourished individuals, potentially leading to life-threatening complications including cardiac arrhythmias, respiratory failure, and encephalopathy. 1

Definition and Pathophysiology

Refeeding syndrome occurs when:

• Nutrition (oral, enteral, or parenteral) is reintroduced too rapidly after a period of starvation
• The sudden increase in carbohydrate intake triggers a metabolic shift from fat to carbohydrate metabolism
• This shift causes:
  • Increased insulin secretion
  • Rapid intracellular movement of phosphate, potassium, and magnesium
  • Fluid and sodium retention
  • Thiamine deficiency

High-Risk Populations

Patients at highest risk include those with:

• Chronic alcoholism
• Severe chronic undernutrition
• Anorexia nervosa
• Depleted patients with acute illness 1

Risk Screening Criteria

Major risk factors (one or more of the following):

• BMI <16 kg/m²
• Unintentional weight loss >15% in 3-6 months
• Little or no nutritional intake for >10 days
• Low baseline levels of potassium, phosphate, or magnesium 1

Additional risk factors (two or more increase risk):

• BMI <18.5 kg/m²
• Unintentional weight loss >10% in 3-6 months
• Little or no nutritional intake for >5 days
• History of alcohol misuse or chronic drug use (insulin, antacids, diuretics) 1

Clinical Manifestations

Refeeding syndrome typically presents within the first four days of nutrition therapy with:

• Electrolyte abnormalities:

  • Hypophosphatemia (most common and drives many complications)
  • Hypokalemia
  • Hypomagnesemia
  • Hypocalcemia

• Clinical symptoms:

  • Fluid retention with peripheral edema
  • Congestive heart failure
  • Cardiac arrhythmias
  • Respiratory failure
  • Delirium and encephalopathy
  • Neuromuscular dysfunction (weakness, seizures)
  • Hematologic complications 1, 2

Prevention and Management

Prevention Strategy

1. Identify at-risk patients using the screening criteria above

2. Start nutrition at low levels for high-risk patients:

   • Begin with 5-10 kcal/kg/day 3
   • Prefer enteral over parenteral nutrition when possible
   • Gradually increase feeding over 4-7 days until reaching full nutritional requirements 3

3. Prophylactic supplementation before initiating refeeding:

   • Thiamine: 300 mg IV before starting nutrition, then 200-300 mg IV daily for at least 3 more days 3
   • Electrolytes (even with mild deficiency):
     • Potassium: 2-4 mmol/kg/day
     • Phosphate: 0.3-0.6 mmol/kg/day
     • Magnesium: 0.2 mmol/kg/day IV or 0.4 mmol/kg/day orally 3
   • Water-soluble and fat-soluble vitamins (A, D, K, folate, pyridoxine) 3

Monitoring Protocol

• Daily monitoring of electrolytes (phosphate, potassium, magnesium) for the first week
• Regular assessment of fluid balance
• Close cardiac monitoring in severe cases
• Weight monitoring and recording
• Regular reassessment of nutritional status and adjustment of interventions 3

Treatment of Established Refeeding Syndrome

If refeeding syndrome develops despite preventive measures:

• Reduce or temporarily stop nutritional support
• Aggressively correct electrolyte abnormalities
• Monitor cardiac function
• Address specific complications (respiratory support, neurological management)
• Resume feeding at lower rates once stabilized

Special Considerations

Pediatric Patients

Refeeding syndrome can affect children, with an estimated incidence of up to 7.4% in pediatric intensive care units receiving nutritional support 2. The principles of prevention and management are similar to adults, but require weight-appropriate dosing.

Oncology Patients

Cancer patients are particularly vulnerable to refeeding syndrome due to multiple comorbidities and malnutrition associated with their disease and treatments 4. Extra vigilance is required when reintroducing nutrition in this population.

Anorexia Nervosa

Patients with anorexia nervosa represent a particularly high-risk group. Recent research suggests that current caloric restriction recommendations may be too stringent and require updating 5. However, careful monitoring remains essential.

Common Pitfalls to Avoid

• Failure to identify at-risk patients before initiating nutritional support
• Overly aggressive refeeding in malnourished patients
• Inadequate electrolyte supplementation before and during refeeding
• Neglecting thiamine supplementation before starting carbohydrate intake
• Insufficient monitoring of electrolytes and clinical status during refeeding
• Underestimating the severity of potential complications

By following a structured approach to prevention and management, the potentially fatal complications of refeeding syndrome can be avoided in vulnerable patients.