Diagnostic Performance of Serum Leucine-Rich Alpha-2-Glycoprotein 1 in Pediatric Acute Appendicitis: A Prospective Validation Study

<b>Introduction:</b> Leucine-rich alpha-2-glycoprotein 1(LRG-1) is a human protein that has shown potential usefulness as a biomarker for diagnosing pediatric acute appendicitis (PAA). This study aims to validate the diagnostic performance of serum LRG-1 in PAA. <b>Material and Methods:</b> This work is a subgroup analysis from BIDIAP (BIomarkers for DIagnosing Appendicitis in Pediatrics), a prospective single-center observational cohort, to validate serum LRG-1 as a diagnostic tool in PAA. This analysis included 200 patients, divided into three groups: (1) healthy patients undergoing major outpatient surgery (<i>n</i> = 56), (2) patients with non-surgical abdominal pain (<i>n</i> = 52), and (3) patients with a confirmed diagnosis of PAA (<i>n</i> = 92). Patients in group 3 were divided into complicated and uncomplicated PAA. In all patients, a serum sample was obtained during recruitment, and LRG-1 concentration was determined by Enzyme-Linked ImmunoSorbent Assay (ELISA). Comparative statistical analyses were performed using the Mann-Whitney U, Kruskal-Wallis, and Fisher's exact tests. The area under the receiver operating characteristic curves (AUC) was calculated for all pertinent analyses. <b>Results:</b> Serum LRG-1 values, expressed as median (interquartile range) were 23,145 (18,246-27,453) ng/mL in group 1, 27,655 (21,151-38,795) ng/mL in group 2 and 40,409 (32,631-53,655) ng/mL in group 3 (<i>p</i> < 0.0001). Concerning the type of appendicitis, the serum LRG-1 values obtained were 38,686 (31,804-48,816) ng/mL in the uncomplicated PAA group and 51,857 (34,013-64,202) ng/mL in the complicated PAA group (<i>p</i> = 0.02). The area under the curve (AUC) obtained (group 2 vs. 3) was 0.75 (95% CI 0.67-0.84). For the discrimination between complicated and uncomplicated PAA, the AUC obtained was 0.66 (95% CI 0.52-0.79). <b>Conclusions:</b> This work establishes normative health ranges for serum LRG-1 values in the pediatric population and shows that serum LRG-1 could be a potentially helpful tool for diagnosing PAA in the future. Future prospective multicenter studies, with the parallel evaluation of urinary and salivary LRG-1, are necessary to assess the implementability of this molecule in actual clinical practice.