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.

Voiding cystourethrography is mandatory in infants with febrile urinary tract infection.

Vesicoureteral reflux (VUR) is common condition in infants with febrile urinary tract infections (UTIs). Both VUR and febrile UTIs are risk factors for renal scars, characterized by glomerular hypertrophy with global or segmental sclerosis as cardinal features in pathology. Because renal scars may cause hypertension or chronic kidney diseases in later life, voiding cystourethrography (VCUG) has been mandatory for infants following their first febrile UTIs to identify VUR. However, increasing evidence suggests that the presence of VUR may not represent a direct risk factor for renal scars, which has led to an increase in the use of a stratified approach, in which VCUG is not performed for all patients. This study was conducted to verify whether the stratified approach is justified to identify infants at risk for renal scarring. The medical records of 306 infants with first febrile UTIs (median age, 4 months; 0-72 months) were reviewed. VUR was detected in 40.4% (67/166) of patients by the non-stratified approach, in which VCUG was performed in all patients. In contrast, VUR was identified in only 27.1% (38/140) of patients by the stratified approach, in which VCUG was performed only in the patients with high risk of developing renal scars. This difference in the discovery rate was significant (p = 0.02). Renal bladder ultrasonography had the sensitivities of as low as 45.7% and 52.9% in detecting VUR and in predicting renal scarring assessed by renal scintigraphy, respectively. In conclusion, VCUG should be performed in all infants after their first febrile UTIs.