Plasma Neutrophil Gelatinase-Associated Lipocalin as a Predictor of Renal Parenchymal Involvement in Infants With Febrile Urinary Tract Infection: A Preliminary Study

Abstract

Background: Urinary tract infection (UTI) is the most common bacterial infection in infants. Renal parenchymal involvement is an important prognostic factor; however, early detection of parenchymal involvement in UTI may be difficult during infancy. This study aimed to assess whether a recently established biomarker of UTI, neutrophil gelatinase-associated lipocalin (NGAL), can serve as a useful marker for the detection of cortical defects (CD) and to determine the appropriate diagnostic cut-off value of NGAL in infants with febrile UTI.

Methods: Infants hospitalized for febrile UTI were divided into two groups according to the presence of cortical defects on dimercaptosuccinic acid (DMSA) scintigraphy. Among 64 enrolled infants, 43 (67%) had CD (UTI-CD) and 21 (33%) had no CD (UTI-ND). The white blood cell count, C-reactive protein, and plasma NGAL (pNGAL) levels were determined before antibiotic therapy and compared between the two groups.

Results: pNGAL level was significantly higher in the UTI-CD group than in the UTI-ND group (340 μg/L vs 214 μg/L, P=0.002). Multivariate analysis showed that pNGAL level was the only independent predictor of CD (odds ratio 2.759, P=0.039). In the ROC curve analysis, pNGAL showed the highest area under the curve (0.745; 95% confidence interval, 0.561-0.821; P=0.014). The appropriate cut-off value of pNGAL was 267 μg/L (sensitivity, 72.1%; specificity, 71.4%).

Conclusions: pNGAL was found to be a useful marker for early prediction of renal parenchymal involvement in infants with febrile UTI.

Keywords: Cortical defect; Infant; Neutrophil gelatinase-associated lipocalin; Urinary tract infection.

Fig. 1. ROC curve analysis for the detection of cortical defects in infants with febrile urinary tract infection.

^*The cut-off point selection in the context of ROC curve analysis is the maximum of the Youden index with the level of confidence set at 95%; ^†Two-by-two tables were used to calculate sensitivity, specificity, PPV, and NPV for cut-off value of variables and the level of confidence set at 95%. Abbreviations: WBC, white blood cells; CRP, C-reactive protein; pNGAL, plasma neutrophil gelatinase-associated lipocalin; AUC, area under curve; CI, confidence interval; PPV, positive predictive value; NPV, negative predictive value.