Refeeding syndrome

From IDWiki

Definition

  • Potentially fatal fluid and electrolyte shifts that occur in malnourished patients who receive artificial refeeding
  • Most notable shift causes hypophosphatemia

Pathophysiology

  • During starvation, electrolytes shift from intracellular to intravascular to maintain intravascular levels
  • An increase in serum glucose (from refeeding) causes release of insulin, which stimulates fat, glycogen, and protein synthesis and shifts phosphate, potassium, and magnesium intracellularly
    • The increase in cellular activity requires phosphate, which is pulled in from the serum and is already decreased from malnutrition
    • Hypophosphatemia causes a number of problems
    • Hypokalemia causes arrhythmias
    • Hypomagnesemia causes arrhythmias and muscle dysfunction
  • Due to thiamine deficiency, refeeding risks Wernicke's encepalopathy or Korsakoff syndrome

Risk factors

  • Chronic alcoholism
  • Oncology patients
  • Elderly patients with multiple comorbidities
  • Uncontrolled diabetes mellitus
  • Chronic malnutrition
  • High stress patients unfed for 7 or more days
  • Malabsorptive syndrome
    • Inflammatory bowel disease
    • Short gut syndrome
    • Cystic fibrosis
    • Chronic pancreatitis

Clinical Manifestations

  • History of severely restricted intake
  • Physical exam
    • Loss of subcutaneous fat, indicated by a loss of fullness or loose skin in the following areas:
      • Triceps
      • Costal margin at the midaxillary line
      • Interosseous and palmar areas
      • Deltoid
    • Muscle wasting, indicated by:
      • Quadriceps losing bulk or tone
      • Deltoids, with a more squared-off appearance of the shoulders
    • Edema from extravasation of fluid, indicated by:
      • Ankle edema
      • Sacral edema
      • Ascites

Investigations

  • Electrolytes and extended electrolytes
    • Hypophosphatemia
    • Hypokalemia
    • Hypocalcemia
    • hypomagnesemia

Complications

  • Hypophosphatemia
    • Neurologic: fits, weakness, paresthesia, altered mental status, acute encepalopathy
    • Muscular: weakness, myalgia, rhabdomyolysis
    • Cardiac: decreased contractility, cardiomyopathy
    • Hematologic: platelet and leukocyte dysfunction, thrombocytopenia, hemolysis
    • Respiratory: respiratory muscle dysfunction
    • Bone: osteomalacia
    • Renal: acute tubular necrosis
  • Hypomagnesemia
    • Neurologic: tetany, paresthesias, seizures, ataxia, tremor, weakness
    • Cardiac: arrhythmias including torsades de pointes, hypertension
    • Gastrointestinal: anorexia, abdominal pain
    • Electrolytes: hypokalemia, hypocalcemia
  • Hypokalemia
    • Neurologic: paralysis, paresthesias
    • Muscular: rhabdomyolysis, respiratory depression, weakness
    • Cardiac: arrhythmias, hypotension, cardiac arrest
    • Gastrointestinal: constipation, paralytic ileus
  • Hypoglycemia
  • Metabolic alkalosis

Management

  • Patients starting parenteral nutrition
    • Include phosphate supplementation
  • Patients at risk of refeeding syndrome
    • Identify patients at risk
    • Check extended electrolytes (calcium, magnesium, potassium, phosphate)
    • Before feeding
      • Thiamine 200-300mg po once daily or 250mg IV once daily or 100mg once daily for three days
      • Multivitamin po once daily
    • Careful rehydration with electrolyte supplementation
    • Start feeds at no more than 50% of total daily energy requirements (50% of ~30 Kcal/kg/day) with full protein requirement (~1-1.2g/kg/day)
    • Monitor electrolytes for first two weeks, supplementing as necessary

Further Reading