Reduced urinary excretion of neutrophil gelatinase-associated lipocalin as a risk factor for recurrence of febrile urinary tract infection in children

Background This study aimed to test the hypothesis that reduced urinary excretions of neutrophil gelatinase-associated lipocalin (NGAL) predispose children to recurrence of febrile urinary tract infection (fUTI). Methods Subjects were 38 children diagnosed with fUTI. To examine risk factors for recurrence of fUTI, the subjects were divided into a non-recurrent group and a recurrent group according to the presence or absence of fUTI over 3 years since the first episode. We measured the urinary NGAL levels in patients with fUTI at the non-infected stage in addition to age-matched healthy control children. Results In a multiple logistic regression analysis, significant differences between the groups were not observed for age, sex, the prevalence of kidney scarring and bladder bowel dysfunction, urinary beta 2-microglobulin/creatinine (Cr) level, and serum levels of Cr and Cystatin C, while the recurrent group had significantly more cases with grade III or higher vesicoureteral reflux (p < 0.01). Furthermore, the urinary NGAL/Cr in the recurrent group (median, 3.60 mu g/gCr) was significantly lower than that in the non-recurrent group (median, 16.47 mu g/gCr; p < 0.01), and age-matched healthy control children (median, 14.14 mu g/gCr; p < 0.05). The area under the receiver operating characteristic curve of NGAL/Cr was 0.86 for predicting recurrence of fUTI. A cut-off value of 11.59 mu g/gCr had the best accuracy to predict recurrent fUTI yielding a specificity of 78% and a sensitivity of 93%. Conclusions Reduced levels of urinary NGAL, which protects against urinary infection, are a risk factor for recurrence of fUTI and could serve as a biomarker.