Refeeding Syndrome (RFS): Overview 

Refeeding syndrome is a potentially life-threatening metabolic complication that occurs when nutrition is reintroduced to malnourished patients, leading to shifts in fluids and electrolytes. The hallmark is hypophosphatemia, often accompanied by hypokalaemia, hypomagnesemia, and vitamin deficiencies. It can cause cardiac, respiratory, and neurologic complications. 

1. Risk Factors for Refeeding Syndrome 

A. Patient Groups Commonly at Risk 

Severely malnourished patients, e.g., anorexia nervosa, chronic starvation. 
Prolonged fasting or inadequate intake (≥5–10 days without sufficient nutrition). 
Chronic illness leading to malnutrition (e.g., cancer, chronic kidney disease, chronic liver disease, chronic alcoholism, inflammatory bowel disease). 
Elderly patients with poor nutritional intake. 
Postoperative or critical care patients with long-term NPO/NBM status. 
Patients with gastrointestinal malabsorption or prolonged vomiting/diarrhoea. 
Patients with significant weight loss (>10% body weight in 3–6 months). 

B. Laboratory or Clinical Indicators 

Patients may have: 

Low baseline electrolytes: phosphate, potassium, magnesium. 
Low BMI (<18.5 kg/m²). 
Recent history of little or no food intake for >5 days. 
Alcohol use disorder, increasing risk due to thiamine deficiency. 
Insulin-sensitive state after starvation (e.g., sudden glucose intake triggers shifts). 

2. NICE Criteria for High Risk of Refeeding Syndrome (UK Guidelines) 

A patient is high risk if one of the following applies: 

1. BMI <16 kg/m² 
2. Unintentional weight loss >15% in 3–6 months 
3. Little or no nutritional intake for >10 days 
4. Low baseline electrolytes (phosphate, potassium, magnesium) 

Or two or more of the following: 

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 drugs like insulin, chemotherapy, antacids, or diuretics 

3. Key Electrolyte Changes in RFS 

Hypophosphatemia (most critical and diagnostic) 
Hypokalaemia 
Hypomagnesemia 
Thiamine deficiency 

These changes occur due to insulin-driven cellular uptake of phosphate, potassium, and magnesium when carbohydrates are reintroduced. 

4. Clinical Signs to Watch For 

Weakness, fatigue, or muscle pain 
Paraesthesia or numbness 
Seizures (rare) 
Cardiac arrhythmias or heart failure 
Respiratory failure 
Oedema 

5. Nursing Checklist 

When admitting a patient for nutrition: 

Assess BMI, weight loss history, and intake history. 
Check baseline electrolytes (phosphate, potassium, magnesium, calcium), renal function, and glucose. 
Identify high-risk medications or comorbidities. 
Start feeding gradually (start at 5–10 kcal/kg/day for high-risk adults). 
Supplement electrolytes and thiamine before and during feeding. 
Monitor daily electrolytes, fluid balance, and vital signs for at least the first week. 

6. Prevention Strategies 

Slow initiation of feeding, especially in high-risk patients. 
Daily or more frequent monitoring of electrolytes for the first 5–7 days. 
Correct electrolyte deficiencies before starting nutrition. 
Administer thiamine (100 mg/day) and multivitamins. 
Adjust fluids to prevent overload and oedema. 

Summary: High-Risk Indicators (for quick reference)