Creatinine-normalized urinary lipocalin-2 in children with obesity: association with insulin resistance in a cross-sectional study.

Childhood obesity is associated with insulin resistance and early cardiometabolic risk. Lipocalin-2 (LCN2), a biomarker linked to inflammation, metabolic regulation, and renal tubular stress, has been proposed as a potential indicator of obesity-related complications. However, data regarding urinary LCN2 in pediatric obesity remain limited. This study aimed to evaluate 24-h urinary LCN2 levels and their associations with metabolic parameters in children with obesity. This cross-sectional study included 43 children with obesity and 32 age-matched healthy controls aged 11-16 years. Anthropometric and biochemical assessments included fasting glucose, insulin, lipid profile, and renal-related urinary markers. Insulin resistance was assessed using HOMA-IR. Twenty-four-hour urinary LCN2 was measured by ELISA and normalized to urinary creatinine. Group comparisons and exploratory multivariable analyses were performed using appropriate statistical tests. The urinary LCN2/creatinine ratio was significantly higher in children with obesity than in controls. Absolute urinary LCN2 concentrations did not significantly differ between groups. Within the obesity group, urinary LCN2 concentrations were higher in participants classified as insulin resistant. Creatinine-normalized urinary LCN2 differed between children with obesity and controls and showed associations with insulin resistance status. These findings suggest that urinary LCN2 may reflect early metabolic or renal-related alterations in pediatric obesity. Larger prospective multicenter studies are needed to determine its clinical utility.