Low Plasma Sodium Concentration Predicts Perforated Acute Appendicitis in Children: A Prospective Diagnostic Accuracy Study

This prospective study demonstrates that low plasma sodium concentration (≤136 mmol/L) at admission strongly predicts perforated appendicitis in children, with 82% sensitivity and 87% specificity. Elevated arginine vasopressin levels in perforated cases suggest a pathophysiologic mechanism for the hyponatremia, offering clinicians a readily available biomarker to guide urgent surgical decision-making.