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 ß2-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 µg/gCr) was significantly lower than that in the non-recurrent group (median, 16.47 µg/gCr; p < 0.01), and age-matched healthy control children (median, 14.14 µg/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 µg/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.

Urinary C-megalin for screening of renal scarring in children after febrile urinary tract infection.

BackgroundFebrile urinary tract infection (fUTI) in children may cause renal scarring. This study aimed to investigate the usefulness of urinary biomarkers for diagnosing renal scarring after fUTI.MethodsThirty-seven children (median age: 1.36 years, range: 0.52-12.17 years, 25 boys) with a history of fUTI, who underwent renal scintigraphy for 4 months or longer after the last episode of fUTI, were analyzed. A spot urine sample was obtained on the day of renal scintigraphy to measure levels of total protein, N-acetyl-ß-D-glucosaminidase (NAG), ß2-microglobulin (BMG), neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP), and C-megalin (full-length megalin). Results were corrected for urinary creatinine (Cr) and compared between the group with renal scarring (n=23) and that without scarring (n=14). Urinary levels of C-megalin were also measured in healthy control subjects.ResultsNo significant differences in total protein, NGAL, L-FABP, NAG, and BMG levels were found between the groups. However, C-megalin levels were significantly higher in the renal scarring group than in the non-renal scarring group and healthy controls (P<0.001). A cutoff value of 6.5 pmol/nmol of urinary C-megalin/Cr yielded 73.9% of specificity and 92.9% of sensitivity.ConclusionUrinary C-megalin is useful for diagnosing renal scarring caused by fUTI.