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A. Definitionnavigator

  1. Refeeding of patients with severe weight loss
    1. Anorexia is main cause in USA [2,3]
    2. Cancer or chronic infections (including HIV) may also cause severe weight loss
    3. Starvation due to lack of food in developing countries
  2. Hypophosphatemia and associated complications
  3. Abnormalities in Electrolyte Regulation
    1. Hypokalemia
    2. Hypomagnesemia
  4. Abnormal Glucose Metabolism
  5. Severe Catabolic State

B. Abnormalitiesnavigator

  1. Hypophosphatemia
  2. Hypokalemia
  3. Hypomagnesemia
  4. Abnormal glucose metabolsim
  5. Vitamin Deficiency
  6. Fluid Shifts, Edema

C. Hypophosphatemia navigator

  1. Catabolism of fat and muscle leads to increase in lean muscle mass
  2. Renal mechanisms maintain (near) normal serum electrolyte levels
  3. Refeeding adds carbohydrates to blood, increased insulin secretion
  4. Carbohydrates cause increased uptake of electrolytes (phosphorus, K+, Mg2+) into cells
  5. Severe serum hypophosphatemia results
  6. Depletion of phosphorylated intermediates (phosphate starvation)
    1. ATP
    2. 2,3 DPG
    3. Reduced function of enzyme Glucose 3-phosphate dehydrogenase
  7. Effects of severe (<1mg/dL) hypophosphatemia
    1. Cardiac - decreased myocardial function, arrhythmias, CHF
    2. Hematologic - altered RBC morphology, hemolytic anemia
    3. Hepatic - liver dysfunction (especially in cirrhotics)
    4. Neurologic - areflexic paralysis, confusion, Guillain-Barre Syndrome
    5. Muscular - rhabdomyolysis, weakness
    6. Respiratory - acute ventilatory failure
    7. Skeletal - osteomalacia (long term hypophosphatemia)
    8. Gastrointestinal - nausea, vomiting, poor GI motility
  8. Treatment
    1. Treatment required for symptoms or for serum PO4- <0.32 mmol/L (0.9mg/dL)
    2. Oral therapy is safest, usually 1000mg/d of P
    3. Intravenous (IV) replacement of P carries a high risk of acute hypocalcemia
    4. IV phosphate infusion in normal saline (2.5mg/kg body weight over 6 hours)
    5. Serum phosphate, calcium and magnesium, and electrolytes are monitored

D. Hypokalemia navigator

  1. Body depletion of potassium
  2. Increased insulin excretion leads to potassium uptake by cells
  3. Expansion of extracellular volume
  4. Effects
    1. Cardiac - arrhythmias, cardiac arrest, hypotension, ECG changes
    2. GI - constipation, ileus, worsened encephalopathy
    3. Metabolic - glucose intolerance, hypokalemic metabolic alkalosis
    4. Neurologic - hyporeflexia, paresthesias
    5. Muscular - rhabdomyolysis, weakness, respiratory depression
    6. Renal - reduced urinary concentrating ability, myoglobulinuria

E. Hypomagnesemianavigator

  1. Effects
    1. Cardiac - arrhythmias (torsade de pointes), tachycardia
    2. GI - abdominal pain, constipation
    3. Neurologic - ataxia, confusions, hyperreflexia, irritability, dysesthesias
    4. Muscular - tremors, fasciculations, tetany, weakness
  2. Note that serum and intracellular Mg2+ concentrations are poorly correlated

F. Vitamin Deficiencynavigator

  1. Thiamine deficit may be most important
  2. Thiamine should be given to any malnourished pt prior to glucose

G. Glucose Metabolismnavigator

  1. Infusion of glucose decreases stimulus for gluconeogenesis
  2. This decreases amino acid utilization and helps correct negative nitrogen balance
  3. Caution must be used in glucose infusion to prevent hyperglycemia
  4. Hyperglycemia contributes to dehydration with renal damage, hypotension, etc.
  5. Administration of insulin may help prevent hyperglycemia
    1. Insulin with glucose also suppresses negative nitrogen balance
    2. May increase hypokalemia

H. Risks for Developing Refeeding Syndromenavigator

  1. Anorexia nervosa
  2. Starvation conditions: classic kwashiorkor and classic marasmus
  3. Chronic Underfeeding
  4. Chronic alcoholism
  5. Morbid obesity with massive weight loss
  6. Prolonged fasting or underfeeding, >7-10 days

I. Considerations in Refeedingnavigator

  1. Concern for development of refeeding syndrome
  2. Full panel electrolytes including phosphate, Ca2+, Mg2+ qd x 1 week
  3. Begin low calorie feeding with gradual increase
  4. Administer vitamins routinely including thiamin >100mg/day
  5. Follow urinary electrolytes including phosphate

References navigator

  1. Brooks MJ and Melnik G. 1995. Pharmacotherapy. 15(6):713 abstract
  2. Mehler PS. 2001. Ann Intern Med. 134(11):1048 abstract
  3. Becker AE, Grinspoon SK, Klibanski A, Herzog DB. 1999. NEJM. 340(14):1092 abstract