Biomarkers and Their Association with Kidney Scarring After the First Episode of Febrile Urinary Tract Infection or Vesicoureteral Reflux in Pediatric Patients

Background and Objectives: Children with febrile urinary tract infections (fUTIs) may be at risk for kidney scarring. Inflammatory biomarkers may predict the risk of scarring. The aim of this study was to investigate the predictive role of PCT, CRP and other markers in scarring in pediatric patients with first fUTI. Materials and Methods: The study was in accordance with the institution’s ethics committee (No. 108/2023). Included patients underwent a kidney–ureter–cyst ultrasound (US). The primary outcomes of this study were the associations of procalcitonin (PCT), C-reactive protein (CRP), and white blood cells (WBC) with kidney scarring. The secondary outcomes were the associations of PCT, CRP, and WBC with vesicoureteral reflux (VUR). A p < 0.05 was considered statistically significant. Results: Sixty-five pediatric patients (1–16 years of age) with a first fUTI, from February 2023 to January 2025, were included. Sixteen patients had VUR, and thirteen patients developed kidney scarring. C-reactive protein was significantly elevated in the VUR group (p = 0.026). In a series of logistic regression analyses, abnormal US findings and severe VUR were associated with scarring (p = 0.009 and p = 0.016, accordingly). The optimal cut-off value for PCT in predicting scarring was calculated as 6.05 ng/mL (sensitivity: 36% and specificity: 97%), and for CRP as 3.62 mg/dL (sensitivity: 63.6% and specificity: 62.1%). Conclusions: This study showed a significant difference in CRP levels between the groups with and without VUR. Abnormal US findings and severe VUR were the most significant predictors of kidney scarring. Significant difference was not reached in PCT and WBC levels between the groups with and without VUR or with and without kidney scarring. The small sample size may have influenced the study’s outcomes.