Refeeding Syndrome

Potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial feeding.


  • During prolonged fasting, there are several changes that occurs in the body:
    • Net effect is a switch from carbohydrate metabolism to protein/fat metabolism and a decrease in basal metabolic rate by up to 25%
      • Muscle/liver switch from using ketones to use fatty acids as their source of energy
      • Brain then switches from glucose to ketone utilisation
      • Liver decreases rate of gluconeogenesis to preserve muscle protein
    • Intracellular minerals are depleted, however serum levels often remain normal.
      • Renal excretion of fluid/minerals also reduces
  • During re-feeding
    • glycaemia causes insulin release and decreased release of glucagon, stimulating glycogen, fat and protein synthesis.
      • requiring minerals and vitamins
    • insulin also stimulates the uptake of minerals e.g. K+, PO4+ and Mg2+ into the cells.
      • water follows
      • minerals are already depleted and serum levels rapidly drop
        • the hallmark of refeeding syndrome is hypophosphataemia, although a change in a range of fluid/electrolytes can be seen
  • Incidence/prevalence is not really known, but there is around a 0.4% incidence of severe hypophosphataemia- with malnutrition being the commonest cause.

Conditions increasing risk for RFS

  • Anorexia Nervosa
  • Chronic alcoholism
  • Cancer patients
  • Post-op patients
  • Elderly patients- with comorbidity
  • Uncontrolled diabetes
  • Chronic malnutrition
    • Marasmus (severe malnutrition)
    • Prolonged fasting or a low energy diet
    • Morbid obesity with profound weight loss
    • High stress patient unfed for >7 days
    • Malabsorptive syndromes e.g. Inflammatory bowel disease, chronic pancreatitis, cystic fibrosis, short bowel syndrome
  • Long term users of antacids, diuretics


  • Patients with one or more of
    • BMI <16
    • Unintentional weight loss >15% in the past 6 months
    • Little or no nutritional intake for >10 days
    • Low levels of potassium, phosphate or magnesium before feeding
  • OR two or more of
    • BMI <18.5
    • Unintentional weight loss >10% in the last 6 months
    • Little or no nutritional intake for >5 days
    • History of alcohol/drug misuse, or drug use including insulin, chemotherapy, antacids or diuretics
  • …. are at risk of refeeding syndrome

So check BMI and U&Es (minimum) prior to re-feeding.


  • Prior to re-feeding- administer thiamine (200-300mg daily, vitamin B and other trace elements with supplements daily
  • Start feeding slowly and slowly (no more than 50% of the energy requirements- recommended at 0.0418MJ/kg/day) increase over 4-7 days.
  • Monitor fluid and electrolyte balance and supplement/correct these appropriately
    • Normal levels of potassium (3.6-5mmol/L); normal intake 2.6-4mmol/L
    • Normal levels of calcium (2.1-2.55mmol/l)
    • Normal levels of phosphate (0.8-1.45mmol/l); normal intake 0.3-0.6mmol/l
    • Normal levels of magnesium (0.7-1mmol/l); normal intake 0.2-0.4mmol/l

Potential complications

Refeeding syndrome can affect almost every organ system, due to a mixture of electrolyte disturbances.

  • Serious complications include arrhythmias and cardiac arrest, pulmonary oedema and respiratory failure, seizures/fits, renal failure, metabolic acidosis/ketosis, amongst other things
  • For a longer list, see here
  • These complications often require management in their own right, some of which can worsen other problems.  Prevention of refeeding syndrome is, therefore, the main goal, rather than treatment.

One thought on “Refeeding Syndrome”

  1. I recently had a patient on a 25 day hunger strike (I work in a state facility.) He began re-feeding 4 days ago with dramatic return of normal levels. It was complicated, yet fascinating case.

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