The Role of Hyponatremia in Identifying Complicated Cases of Acute Appendicitis in the Pediatric Population

<b>Background</b>: Hyponatremia has been identified as a marker of disease severity in various inflammatory conditions. However, its role in predicting acute complicated appendicitis (ACA) in children remains under investigation. This study evaluated the association between preoperative hyponatremia and ACA in a pediatric population. <b>Methods</b>: A retrospective study was conducted on pediatric patients treated for acute appendicitis in two major pediatric centers in Greece. Patients were categorized into groups based on the presence of acute uncomplicated appendicitis (AUA) and acute complicated appendicitis (ACA). Preoperative laboratory parameters were analyzed to identify potential predictors of ACA. <b>Results</b>: This study included 491 pediatric patients, with a mean age of 10 years. ACA patients exhibited significantly lower Na levels compared to those with AUA (136 vs. 138 mmol/L, <i>p</i> < 0.001). Hyponatremia (<135 mmol/L) was present in 38.4% of ACA cases compared to 2.2% of AUA cases (<i>p</i> < 0.001), and was associated with a significantly increased risk of ACA (OR = 18.30, <i>p</i> < 0.001). A sodium threshold of 135 mmol/L also demonstrated a sensitivity of 48% and a specificity of 92.1% <b>Conclusions</b>: Hyponatremia is a strong and specific predictor of ACA in children. When combined with other inflammatory markers, it may enhance early risk stratification, aiding in timely surgical decision making.