Background and Aims Infants with renal cortical defect due to acute pyelonephritis (APN) may be associated with an increased risk of progressive kidney damage. Neutrophil gelatinase-associated lipocalin (NGAL) is produced and secreted by renal tubule cells at low levels, but the amount produced and secreted increases dramatically after ischemic, septic, or nephrotoxic injury of the kidneys.

To investigate the usefulness of a rapid blood NGAL assay as a diagnostic marker of cortical defect in infant with febrile UTI at the bedside.

Methods Sixty-three infants with suspected febrile UTI were divided into a documented UTI group(n=49) and a non UTI group(n=14). UTI group were divided into cortical defect (UTI-D) group(n=26) and non cortical defect (UTI-N) group(n=23) according to the result of DMSA scan. Blood NGAL concentrations were analyzed using a commercial kit (Triage NGAL test) by fluorescence immunoassay.

Results NGAL concentrations were significantly higher in UTI-D group (68.0[60.0–172.5] mg/mL) than in UTI-N group (60.0[60.0–86.5] mg/mL) and in non UTI group (60.0[60.0–60.0] mg/mL). In UTI-D groupin, NGAL concentrations were significantly decreased after antibiotic therapy (60.0[60.0–71.2] mg/mL). The area under the ROC curve of NGAL for the detection of cortical defect was 0.74 (p=0.004). The best cutoff NGAL concentrations for the detection of cortical defect was found to be 61.5 mg/mL (sensitivity: 69.2%; specificity 78.2%).

Conclusions Although it is not a stand-alone test, the rapid determination of blood NGAL concentration provides valuable information quickly, concerning the distinction between APN and lower UTI, for determining the clinical course of infant with febrile UTI.