Urine YKL-40 versus Urine NGAL as Potential Markers for Diagnosis of Urinary Tract Infection in Febrile Pediatric Patients

Abstract

Early diagnosis of urinary tract infection (UTI) in pediatric patients is a prob-lem due to the absence of specific symptoms and difficulty in obtaining the proper urine sample. These difficulties increase the need for effective biomarker for UTI diagnosis in young patients. Neutrophil gelatinase-associated lipocalin (NGAL) is proved to be a marker for UTI diagnosis. YKL-40 is a glycosyl hydrolase which is produced locally at the sites of inflammation. The objective of our study is to assess the value of YKL-40 as a possible marker for UTI diagnosis in febrile children and to compare its value versus NGAL. Urine culture was used as a gold standard for UTI diagnosis. The study enrolled three groups; febrile children with positive urine culture, febrile children with negative urine culture, and controls without fever and with negative urine culture. Each group included 50 children from patients attended outpatients clinics department of Mansoura University Children Hospital. For each patient enrolled in the study, complete blood count, C-reactive protein, serum creatinine, urine creatinine, routine urine analysis and urine culture were assessed. Using ELISA test, urine values of NGAL (uNGAL) and YKL-40 (uYKL-40) were measured and normalized to urine creatinine (uNGAL/uCr) and (uYKL40/uCr) respectively. The values of uNGAL, uYKL-40, uNGAL/Cr and uYKL-40/Cr were significantly higher in febrile UTI group. The receiver operating curve (ROC) show the optimum cut off value for urine YKL-40 (171.5 pg) with 84% senstivity, 82% specificity and the area under the ROC curve (AUC) 0.95. The optimum cutoff value of uYKL-40/Cr was (159.2 pg/mg) with 72% sensitivity, 71% specificity and 0.81 AUC. Higher sensitivity and specificity of uYKL-40 and uYKL40/Cr compared to uNGAL and uNGAL/Cr respectively were observed. In conclusion, the diagnostic value of uYKL-40 is superior to that of uNGAL. Urine YKL-40 could be a good marker for diagnosis of UTI in febrile pediatric patients.