Refeeding Syndrome

Refeeding syndrome is an acute metabolic deterioration that can occur when carbohydrate-containing nutrition is restarted after at least 5 days of little or no intake, particularly in a person who is malnourished or has depleted intracellular stores. During prolonged undernutrition, insulin levels fall and the body shifts away from carbohydrate metabolism toward fat and protein breakdown. Phosphate, potassium, and magnesium move out of cells or are consumed in metabolic processes, so total-body stores become dangerously low even when a prefeeding serum result is still within the reference range. The serum value is only the circulating balance; it does not reliably show the size of the intracellular reserve. When carbohydrate is reintroduced, insulin rises. Glucose enters cells, and phosphate, potassium, and magnesium are pulled intracellularly to support glucose use, protein synthesis, and other anabolic work. Thiamine requirements also increase because vitamin B₁ is needed for carbohydrate metabolism. The result may be a rapid fall in serum phosphate, potassium, or magnesium, an abnormal glucose response, and clinically significant thiamine deficiency. Phosphate depletion is especially dangerous because phosphate is required to generate ATP....