What is Refeeding Syndrome in Critical Care?

December 3, 2025 •

2 min read

Recent studies in intensive care units suggest that between 17% and 52% of patients receiving nutritional support experience refeeding syndrome, a potentially fatal metabolic complication. This condition is particularly dangerous for malnourished patients in critical care, demanding a cautious and well-monitored reintroduction of nutrients.

Quick Summary

Refeeding syndrome is a metabolic disturbance in malnourished patients when feeding is restarted, causing severe electrolyte and fluid shifts. This can lead to life-threatening complications like cardiac failure, arrhythmia, and respiratory distress, requiring careful management.

Key Points

Metabolic Shift: Refeeding syndrome is triggered by a sudden metabolic shift from fat-based energy production to carbohydrate utilization, causing rapid and dangerous fluid and electrolyte changes.
Electrolyte Deficiencies: Key features include severe hypophosphatemia, hypokalemia, and hypomagnesemia due to intracellular electrolyte uptake stimulated by insulin.
Critical Care Risks: Critically ill patients are at high risk due to pre-existing malnutrition, prolonged fasting periods, and the presence of comorbidities exacerbating electrolyte imbalances.
Prevention is Key: Prevention involves early identification of at-risk patients through screening, cautious refeeding protocols starting at low caloric levels, and prophylactic supplementation.
Multisystem Complications: Clinical signs can manifest across multiple systems, including severe cardiac arrhythmias, respiratory failure, neurological dysfunction like Wernicke's encephalopathy, and fluid overload.
Vigilant Monitoring: Intensive daily monitoring of serum electrolytes, fluid balance, and clinical status is essential, especially in the first week of refeeding, to detect and correct problems early.

Understanding the Physiology of Refeeding Syndrome

Refeeding syndrome is a complex and potentially fatal metabolic event that can occur when nutrition is reintroduced to a severely malnourished patient. In critical care, this risk is heightened due to pre-existing organ failure, prolonged starvation, and comorbidities.

The Starvation-to-Refeeding Metabolic Shift

During starvation, the body uses fat and protein for energy due to decreased insulin. Essential intracellular electrolytes like phosphate, potassium, and magnesium become depleted from the intracellular space, though serum levels may appear normal. Reintroducing carbohydrates triggers insulin, causing glucose, phosphate, potassium, and magnesium to move into cells. This rapid shift causes dangerously low serum levels and the clinical signs of refeeding syndrome.

The Role of Specific Electrolyte and Vitamin Deficiencies

The most significant biochemical disturbances are low levels of phosphate, potassium, and magnesium. Hypophosphatemia impairs ATP production. Hypokalemia can cause cardiac arrhythmias and muscle weakness. Hypomagnesemia can worsen hypokalemia and contribute to arrhythmias. Thiamine (Vitamin B1) deficiency, crucial for carbohydrate metabolism, can lead to Wernicke's encephalopathy.

Management and Prevention of Refeeding Syndrome in Critical Care

Preventing refeeding syndrome starts with identifying at-risk patients. Guidelines recommend a cautious approach, especially in the ICU.

Patient Risk Assessment in Critical Care

Risk assessment uses criteria like those from the National Institute for Health and Care Excellence (NICE). Key risk factors include BMI below 16 kg/m², significant weight loss (over 15% in 3-6 months), minimal food intake for more than 10 days, and low baseline electrolyte levels (potassium, phosphate, or magnesium).

Comparison of Refeeding Approaches

A comparison of conservative versus aggressive refeeding approaches highlights differences in starting calories, rate of caloric increase, nutrient supplementation strategy, monitoring intensity, risk profile, and suitability for different patient populations.

Clinical Manifestations and Monitoring

In critical care, early detection is vital as symptoms can resemble other conditions. Clinical signs can affect multiple body systems, including cardiovascular (arrhythmias, heart failure risk), neuromuscular (weakness, seizures), fluid balance (edema), neuropsychiatric (delirium, Wernicke-Korsakoff syndrome), and gastrointestinal symptoms. Monitoring involves daily electrolyte and glucose checks, fluid balance assessment, and ECG monitoring for high-risk patients.

Conclusion

Refeeding syndrome is a significant, preventable complication in critical care. Prevention involves risk assessment, cautious feeding initiation, prophylactic supplementation, and rigorous monitoring by a multidisciplinary team.

Frequently Asked Questions

The primary cause is reintroducing carbohydrates to a malnourished patient, causing an insulin surge and rapid intracellular shift of phosphate, potassium, and magnesium, leading to dangerously low blood levels.

Phosphate, potassium, and magnesium are most critically affected, resulting in hypophosphatemia, hypokalemia, and hypomagnesemia.

Early signs can be subtle. In critical care, look for rapid changes in serum electrolytes (especially phosphate) within the first five days of feeding, fluid overload, or cardiac arrhythmias.

Prevention involves identifying at-risk patients. For high-risk individuals, feeding starts cautiously at low calories (e.g., 5-10 kcal/kg/day) with prophylactic thiamine, multivitamins, and electrolytes, gradually increasing over days.

Administer thiamine before starting or increasing nutrition and continue supplementation with multivitamins and B-complex for 7-10 days.

Yes, refeeding syndrome can occur with oral, enteral, or parenteral nutrition. Any sudden increase in calorie and carbohydrate intake can trigger it in an at-risk individual.

Nutritional support is usually slowed or paused. The patient receives aggressive electrolyte and fluid correction, and the feeding plan is adjusted under careful monitoring.