In a patient with anorexia nervosa, which electrolyte finding is most indicative of refeeding syndrome?

Hypophosphatemia is the most indicative electrolyte finding of refeeding syndrome, particularly in the context of a patient recovering from anorexia nervosa. Refeeding syndrome occurs when nutrition is reintroduced to individuals who are malnourished or have been in a prolonged state of starvation. This process leads to a rapid shift of electrolytes, particularly phosphate, from the extracellular to the intracellular space, as the body begins to metabolize carbohydrates again.

Phosphorus is critical for energy production and cellular function, and its depletion during refeeding can result in serious complications, including muscle weakness, respiratory failure, and cardiac dysfunction. Monitoring phosphate levels is essential after initiating nutrition in at-risk patients, as recognizing and addressing hypophosphatemia early can help prevent these adverse outcomes.

While changes in potassium, magnesium, and calcium levels can occur during refeeding syndrome, hypophosphatemia is particularly characteristic and serves as a reliable marker for identifying patients who may be developing this syndrome.