Assessment of urine calprotectin and YKL-40 levels in urinary tract infection diagnosis in children under 2 years of age

Urinary tract infections (UTI) are common cause of fever in children. They often manifest with non-specific symptoms. New markers assessed in non-invasively collected urine are needed for quick and reliable diagnosis. This study evaluates the usefulness of calprotectin and YKL-40 in the diagnosis of febrile UTIs among children. 67 children aged between 1 month and 2 years took part in the study. The study group (group UTI) consisted of children with the first episode of febrile UTI (n = 20). Two control groups were created: group F - febrile children with other than UTI cause of the fever (n = 36), group H - healthy children (n = 11). Concentrations of calprotectin and YKL-40 in urine samples were determined with the use of the enzyme-linked immunosorbent assay method (ELISA). In the UTI group, the average calprotectin concentration was 1273.3 ng/ml, which was significantly higher than in group F (35.4 ng/ml) and in group H (8.0 ng/ml) (p < 0.001). The YKL-40 concentration in the UTI group was 15,542.1 pg/ml, which was also significantly higher than in group F (138.1 pg/ml) and in group H (162 pg/ml) (p < 0.01). These findings suggest that urinary YKL-40 and calprotectin could be useful markers in the differential diagnosis of febrile UTI among children.