Refeeding Syndrome Biochemical Changes

Refeeding syndrome occurs when nutritional support, particularly carbohydrates like intravenous dextrose, is initiated too rapidly in malnourished patients. This triggers a metabolic shift from catabolism to anabolism. Insulin levels rise, driving glucose, phosphate, potassium, and magnesium into cells, leading to potentially dangerous drops in serum electrolyte levels.

Key Electrolyte Alterations

The aggressive reintroduction of nutrition activates anabolic processes, requiring intracellular electrolyte shifts. The primary biochemical alterations observed include:

• Hypophosphatemia: This is the most characteristic and often the first electrolyte abnormality seen. The rapid utilization of phosphate for ATP synthesis during the surge in metabolic activity causes serum phosphate levels to plummet.
• Hypokalemia: Potassium shifts intracellularly along with phosphate.
• Hypomagnesemia: Magnesium also moves into cells, contributing to its depletion in the serum.
• Fluid and sodium retention can occur, potentially leading to edema.

The most critical and defining biochemical alteration associated with refeeding syndrome is the significant decrease in serum phosphate levels.