Refeeding syndrome involves which energy pathway leading to phosphate depletion?

• A. Glycolysis driven by rapid glucose uptake
• B. Lipolysis
• C. Ketogenesis
• D. Proteolysis

Answer: (A)

Refeeding after a period of fasting triggers a surge of insulin, which drives glucose into cells and rapidly accelerates glycolysis. To metabolize this influx of glucose, cells use inorganic phosphate at multiple steps, especially during glycolysis (for phosphorylation of intermediates and for ATP production). As glycolysis and related anabolic processes ramp up, phosphate shifts from the bloodstream into cells, leading to hypophosphatemia. This intracellular phosphate depletion is a hallmark of refeeding syndrome and can contribute to complications like weakness, respiratory failure, and arrhythmias. Lipolysis, ketogenesis, and proteolysis are more associated with the fasting state and do not explain the rapid phosphate draw into cells seen with refeeding.