Refeeding syndrome

RS is a spectrum of biochemical or clinical alterations that occur as a consequence of the re-introduction of calories after a period of decreased caloric intake.

Refeeding syndrome may develop, especially in severely malnourished patients at the beginning of nutritional therapy as the initial caloric and fluid provision occurs.

As the supply of glucose increases insulin levels, phosphate, potassium, and magnesium shift intrecellularly in the blood and serum concentrations are decreased.

Acute development of electrolyte loss, fluid retention, impaied glucose metabolism that occurs with the oral, enteral or intravenous feeding of malnourished individuals.

Metabolic hallmark is hypophosphatemia, but hypokalemia and hypomagnesemia are common.

The hallmark of the syndrome is a decreased serum concentrations of intracellular electrolytes, especially phosphate, potassium and magnesium.

The RS is defined as a greater than 10% decrease in the serum levels of at least one among: phosphate, potassium, and magnesium, associated or not with organ dysfunction resulting from the decrease in any of these or due to thiamine deficiency occurring within five days of the initiation of energy provision.

The consequences of RF affect the cardiovascular system with decreased cardiac contractility, arrhythmias, water retention, and volume overload, nervous system changes of altered mental status and seizures, reduced oxygen released to tissues due to decreased production of 2,3-DPG, and skeletal muscle weakness, muscle spasms and rhabdomyolysis.

Loss of lean skeletal muscle mass and visceral protein stores which are tissues that contain significant amounts of phosphate, results in depletion of phosphates and decreased body phosphate load.

Hypophosphatemia in refeeding syndrome results from transcellular shift in phosphate and increased tissue requirements during anabolism.

May be as common as 25% incidence in patients with cancer being administered enteral or parenteral nutrition and generally occurs within 72 hours of onset of feedings.

May be associated with cardiac failure or arrhythmias related to declines in serum electrolytes phosphorus, potassium, and magnesium.

Seen in prisoners of war and in anorexia nervosa patients.

Frequently unrecognized and underdiagnosed.

Not necessarily associated with excess mortality:Studies show nonsignificant trend toward Increased mortality in the short term and with a significant increased mortality in the median term.

The use of refeeding nutritional care may be effective for the limitation of excess mortality.