Refeeding syndrome is characterized by depletion of which electrolytes as a result of aggressively refeeding malnourished patients?

• A. Sodium and chloride depletion
• B. Phosphorus, magnesium and potassium depletion
• C. Calcium and bicarbonate depletion
• D. Sulfate and phosphate depletion

Answer: (B)

Refeeding syndrome happens when a malnourished patient is fed again too quickly, and the sudden rise in insulin drives glucose and other nutrients into cells. This creates a sharp intracellular shift of minerals that are needed for energy and cellular function, so their serum levels drop in a characteristic way. Phosphorus is most notably depleted because it’s essential for ATP production and many phosphorylation reactions; without adequate phosphate, cells can’t make energy effectively, leading to widespread dysfunction. Magnesium follows because insulin stimulates its movement into cells and it’s a crucial cofactor for many enzymes and for maintaining electrical stability in muscles and the heart. Potassium also shifts into cells, and low potassium can provoke arrhythmias, muscle weakness, and impaired respiration. Together, deficits in phosphorus, magnesium, and potassium define refeeding syndrome.

Sodium and chloride depletion isn’t the hallmark pattern, and while shifts can occur, they aren’t the classic trio; calcium and bicarbonate depletion aren’t typical features of this syndrome; sulfate depletion isn’t part of the recognized pattern. Understanding the trio helps explain the major risks and why careful, gradual refeeding with close electrolyte monitoring is essential.