II. Definitions

  1. Refeeding Syndrome
    1. Metabolic imbalance complicating initial refeeding of a severely malnourished patient
    2. Occurs in first 7 days (typically first 3 days) if refeeding is too aggressive
    3. Results in severe Electrolyte abnormalities with risk of Cardiac Dysrhythmias and death

III. Pathophysiology

  1. Severely malnourished patients are starting with depleted energy and Electrolyte stores
    1. Energy stores including glycogen, adipose tissue and Muscle are depleted
    2. Electrolytes including Potassium, Magnesium and Phosphorus are depleted
    3. Thiamine deficiency
  2. High Caloric Intake reintroduced in a severely malnourished patient (e.g. Anorexia Nervosa)
    1. Metabolism shifted to anabolic from catabolic
    2. Triggers Insulin release
    3. Insulin promotes intracellular shifts of Potassium, Magnesium, Phosphorus and water
    4. Insulin stimulates glycogen, fat, and Protein synthesis and further depletes Electrolytes
  3. Abrupt Electrolyte shifts result in potentially life-threatening complications
    1. Hypophosphatemia results in diminished ATP and Muscle Weakness
    2. Hypokalemia may result in Arrhythmias, Muscle Weakness and ileus
    3. Hypomagnesemia risks Arrhythmias and Seizures
  4. Fluid balance also shifts with refeeding
    1. Risk of Fluid Overload (Congestive Heart Failure, Pulmonary Edema)

IV. Risk Factors

  1. Rapid weight loss prior to refeeding
  2. Rapid refeeding
  3. Severe malnourishment
    1. Body Mass Index <16 kg/m2
    2. Unintentional Weight Loss >15% in the past three to six months
    3. Minimal nutritional intake for >10 days
  4. Preexisting Electrolyte deficiency prior to starting refeeding
    1. Hypokalemia
    2. Hypomagnesemia
    3. Hypophosphatemia
  5. Comorbidity
    1. Chronic Malnutrition
    2. Anorexia Nervosa
    3. Alcoholism
    4. Elderly
    5. Postoperative patients
    6. Diabetes Mellitus
    7. Cancer
    8. Morbidly obese patients with profound weight loss
    9. Malabsorption (e.g. Inflammatory Bowel Disease, Cystic Fibrosis, Chronic Pancreatitis, short bowel syndome)
    10. Long-term Diuretic use
    11. Long-term Antacids (Magnesium or aluminum salts)

V. Labs

  1. Complete Blood Count
    1. Hemolytic Anemia
  2. Creatine Phosphokinase (CPK)
    1. Rhabdomyolysis
  3. Monitor Electrolytes closely in first 7 days of refeeding (esp. first 3 days)
    1. Serum Phosphorus
      1. Severe Hypophosphatemia is the hallmark finding in Refeeding Syndrome
    2. Serum Potassium
    3. Serum Magnesium
    4. Serum Sodium
    5. Thiamine deficiency

VI. Diagnostics

  1. Monitor inpatients on telemetry
  2. Electrocardiogram findings with risk of cardiovascular collapse
    1. Prolonged QT interval (Risk of sudden death)
    2. Bradycardia with Heart Rate <40 beats per minute

VIII. Prevention

  1. Obtain baseline labs prior to refeeding and monitor during refeeding
  2. Avoid excessive Intravenous Fluids
  3. Before starting refeeding
    1. Normalize Electrolytes
    2. Thiamine 300-400 mg daily orally
    3. Vitamin B supplementation
  4. Initiate weight gain slowly
    1. See Anorexia Nervosa for management
    2. See Specialized Nutritional Support
    3. Start refeeding at one third or less of nutritional needs and gradually increase every 5-7 days
    4. Limit initial Energy Intake to 20 to 25 kcal/kg/day
    5. Early Consultation to nutrition specialist

IX. Prognosis

  1. Life threatening complication if not recognized

X. References

  1. Renbarger and Pearson (2021) Crit Dec Emerg Med 35(8): 17-23
  2. Mehanna (2008) BMJ 336(7659):1495-8 +PMID: 18583681 [PubMed]

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