Hyponatremia as a predictor of perforated acute appendicitis in pediatric population: A prospective study.

Background: The aim of this study was to investigate hyponatremia as a new biochemical marker associated with complicated appendicitis in the pediatric population.

Methods: Pediatric patients (n = 184) with acute appendicitis confirmed by histopathology were enrolled in a prospective cohort study from January 2019 to May 2020. Medical history, demographic and clinical data were recorded in the study protocol. Blood samples for biochemical analysis, electrolytes and acute inflammatory markers were taken before surgery. Patients were further divided in two groups, those with non-perforated (n = 148; 79%) and perforated appendicitis (n = 38; 21%).

Results: The mean serum sodium level in patients with complicated appendicitis was significantly lower compared to patients with non-complicated appendicitis (132.2 mmol/L vs. 139.2 mmol/L, p < 0.001). The receiver operating characteristic curve of plasma sodium concentration in patients who were diagnosed with perforated acute appendicitis showed an area under the curve of 0.983 (95% CI, 0.963-1.00). A cut-off-value of plasma sodium concentration of ≤135 mmol/L was shown to give the best possible sensitivity and specificity, 94.7% (95% CI: 82.2-99.3) and 88.5% (95% CI: 88.2-93.2) respectively (p < 0.001). Patients with complicated appendicitis were more likely to be younger than five years of age (10.5% vs. 1.4%, p = 0.005), have a duration of symptoms for >24 h (97.4% vs. 59.6%, p < 0.001), sodium serum concentration ≤135 mmol/L (89.5% vs. 5.5%, p < 0.001), body temperature >38.5 °C (47.4% vs. 11.0%, p < 0.001) and CRP serum concentration >62 mg/L (26% vs. 2%, p < 0.001).

Conclusions: Hyponatremia is a novel and very discriminative marker of complicated appendicitis in the pediatric population, and is therefore recommended in appendicitis diagnostic and treatment planning. Methods: Prospective comparative study LEVEL OF EVIDENCE: II.