In the context of refeeding, which electrolyte disturbance is most concerning?

• A. Hyperkalemia
• B. Hypercalcemia
• C. Hypophosphatemia
• D. Hyponatremia

Answer: (C)

In refeeding, the key issue is insulin-driven shifts that move electrolytes into cells as metabolism revs back up after malnutrition. Phosphate is essential for ATP production and energy transfer in every cell, especially in muscles involved in breathing and heart function. When nutrition is reintroduced too quickly, serum phosphate can plummet as phosphate is taken up by cells to support renewed glycolysis and ATP synthesis. This hypophosphatemia can lead to serious and life-threatening problems such as respiratory muscle weakness and failure, cardiac dysfunction, hemolysis, rhabdomyolysis, and impaired immune function. Because of these potentially severe consequences, low phosphate is the most concerning disturbance during refeeding. Other shifts like potassium or magnesium changes can occur, but the danger and prevalence of phosphate depletion make it the primary worry in refeeding scenarios.