Appendicitis stands as the most common surgical emergency in pediatric populations. Despite the existence of numerous diagnostic biomarkers, their utility is constrained by limitations in cost-effectiveness, potentially leading to therapeutic delays. This research aims to determine the diagnostic accuracy of the derived neutrophil-to-lymphocyte ratio (dNLR) in appendicitis. Although its role in this context has been recently described, this is the first study to compare its performance against acute-phase reactants routinely employed in clinical practice. Following approval from the Research Committee (2023/390894), a diagnostic study was conducted including patients under 15 years old undergoing surgery for acute appendicitis (AA) and those presenting with non-surgical abdominal pain (AP).