Refeeding Syndrome

Refeeding syndrome is a metabolic condition that typically occurs in individuals receiving nutritional therapy (e.g., oral, enteral, or parenteral nutrition) after a period of severe malnutrition. Hallmarks of refeeding syndrome include electrolyte shifts, such as hypophosphatemia, hypokalemia, and hypomagnesemia; vitamin deficiencies, especially vitamin B1 (i.e., thiamine); fluid imbalances; and salt retention. Such shifts may lead to impaired organ function and cardiac arrhythmias. Although refeeding syndrome is associated with severe and potentially life-threatening complications, it is a preventable condition.

Refeeding syndrome is caused by the sudden introduction of glucose after a prolonged state of starvation. This may occur when someone is severely malnourished, due to an illness or when someone actively deprives themselves of food, for instance in people with anorexia nervosa, undergoing hunger strikes, or through extreme dieting. In these situations, blood glucose levels are low and as a result, cellular metabolism slows down considerably. When an individual in this state starts eating again, or receives nutritional therapy in a hospital setting, glucose levels increase rapidly and a large amount of insulin is released to push the glucose into the cells. This causes a demand for phosphate and other electrolytes in the cells and results in sudden electrolyte shifts, leading to hypophosphatemia, hypokalemia, and hypomagnesemia. In addition, there is a shift of sodium out of the cell, as potassium is pumped back into cells via the sodium-potassium pump. As a result sodium concentrations increase, leading to fluid retention. 

Signs and symptoms of refeeding syndrome depend on the severity of the electrolyte imbalances. Since phosphate, potassium, and magnesium are all important intracellular ions, their deficiency may lead to muscle weakness, seizures, rhabdomyolysis (i.e., breakdown of muscle tissue), impaired respiratory function, cardiac arrhythmias, peripheral edema, heart failure, and even death. 

Refeeding syndrome is typically diagnosed when there is a high clinical suspicion and laboratory tests show the characteristic electrolyte changes (e.g., elevated glucose levels, hypophosphatemia, hypokalemia, and hypomagnesemia). In most cases, no other tests are needed to confirm the diagnosis. 

Risk factors for refeeding syndrome include a low body weight (i.e., BMI < 18.5 kg/m2); unintentional weight loss of more than 10-15% in the past 3 to 6 months; little or no nutritional intake for 5 or 10 consecutive days; and low electrolyte levels before starting the refeeding process. People at risk of developing refeeding syndrome include elderly or frail individuals; those with eating disorders or chronic alcohol use; individuals with chronic malnutrition (e.g., inflammatory bowel disease, chronic pancreatitis, cystic fibrosis, short bowel syndrome, bariatric surgery); and long-term users of antacids or diuretic medications. 

People at risk for refeeding syndrome may undergo a risk assessment before initiating nutritional therapy. In addition, monitoring of electrolyte levels and clinical symptoms in people at risk, as well as slow titration of nutritional therapy are recommended during the first 72 hours of the refeeding process. 

Treatment of refeeding syndrome focuses on electrolyte and vitamin supplementation, as well as reduced energy intake and fluid administration. To prevent refeeding syndrome, caloric intake should be increased by only 200 to 300 kilocalories per day every 3 to 5 days until sustained weight gain is achieved at target levels. A potential trigger of refeeding syndrome is intravenous infusions of glucose prior to feeding, so this should be avoided.

Refeeding syndrome is a metabolic complication that occurs when nutrition is reintroduced after a period of severe malnutrition. Risk factors include having an eating disorder and chronic illnesses which have led to malnutrition. Hallmarks of refeeding syndrome include electrolyte imbalances (i.e., hypophosphatemia, hypokalemia, and hypomagnesemia) and vitamin deficiencies, which may ultimately cause impaired organ function and cardiac arrhythmias. Treatment is based on replenishing electrolyte and vitamin deficiencies as well as reducing fluid and caloric intake for the first few days of nutritional therapy.