Urinary Neutrophil-Gelatinase Associated Lipocalin is a Potential Noninvasive Marker for Renal Scarring in Patients With Vesicoureteral Reflux

Exploring the Utility of Urinary Creatinine Adjustment for KIM-1, NGAL, and Cystatin C for the Assessment of Kidney Function: Insights from the C-KidnEES Cohort

Normalization of urinary biomarkers of kidney injury is a common practice in clinical and research settings to account for variations in urine concentration, and urinary creatinine is often used as a reference. However, to date, there is no consensus on the adjustment of urinary biomarkers with creatinine, and both absolute and creatinine-adjusted biomarker levels are adopted for making interpretations of kidney health. Hence, the present study aimed to investigate the associations of urinary creatinine with three widely used kidney injury biomarkers, KIM-1, NGAL, and cystatin C, to validate the applicability of urinary creatinine as a reference for normalization. A cross-sectional study was performed with 2100 students, 10-18 years of age in the Children's Kidney Environmental Exposure Study (C-KidnEES) cohort established in Sri Lanka. As identified in linear regression analyses, normalization of urinary KIM-1, NGAL, and Cys-C to urinary creatinine did not result in significant under-adjustment or over-adjustment to the absolute urinary concentrations, giving no specific rationale for creatinine adjustment. Hence, absolute urinary concentrations of the above biomarkers can be adopted for the characterization of subclinical kidney injury in adolescents in community studies where early morning urine sampling is practiced. However, for spot urine samples, consideration of both absolute and creatinine-adjusted biomarker levels would be a better approach.

The Utility of Noninvasive Urinary Biomarkers for the Evaluation of Vesicoureteral Reflux in Children

Vesicoureteral reflux (VUR) is one of the most important disorders encountered in pediatric nephrology due to its frequency and potential evolution to chronic kidney disease (CKD). The aim of our study was to identify noninvasive and easy-to-determine urinary markers to facilitate the diagnosis and staging of VUR. We performed a cross-section study including 39 patients with VUR followed over three years (August 2021-September 2023) and 39 children without urinary disorder (the control group). We measured the urinary concentration of interleukin-6 (IL-6), cathelicidin (LL-37), and neutrophil gelatinase-associated lipocalin (NGAL) in VUR and healthy controls. Moreover, we analyzed the correlation between these biomarkers and the presence of renal scars (RS), reflux nephropathy (RN), and CKD. The NGAL concentrations were significantly higher in patients with VUR than in the controls (p = 0.02). Regarding the severity of the reflux, NGAL/creatinine and LL-37/creatinine were positively correlated with severe reflux (p = 0.04, respectively, p = 0.02). In patients with VUR and RS, LL-37/creatinine was significantly lower (p = 0.01). LL-37/creatinine with an AUC of 0.71 and NGAL/creatinine with an AUC of 0.72 could be acceptable diagnostic tests for severe VUR. In conclusion, urinary IL-6, NGAL, and LL-37 could serve as valuable markers for diagnosing and predicting outcomes in patients with VUR and RN.

The Role of Urinary NGAL in the Management of Primary Vesicoureteral Reflux in Children

Vesicoureteral reflux (VUR) is the most frequent congenital urinary tract malformation and an important risk factor for urinary tract infections (UTIs). Up to 50% of children with VUR may develop reflux nephropathy (RN), and the diagnosis and monitoring of renal scars are invasive and costly procedures, so it is paramount to find a non-invasive and accurate method to predict the risk of renal damage. Neutrophil gelatinase-associated lipocalin (NGAL) has already proven to be a good predictive biomarker in acute kidney injuries, but there are few studies that have investigated the role of NGAL in primary VUR in children. Our aim is to review the predictive value of urine NGAL (uNGAL) as a non-invasive biomarker of RN in children with primary VUR, as well as its ability to predict the evolution of chronic kidney disease (CKD). Based on our analysis of the available original studies, uNGAL can be an accurate and reliable biomarker of RN and its progression to CKD. Some studies suggested a good correlation between VUR severity and uNGAL levels, but other studies found no significant correlation. The relationship between VUR severity and uNGAL levels is likely complex and influenced by factors such as UTIs, the timing of the urine sample collection, and the age and overall health of the patient.

Utility of urinary biomarkers neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 as a marker for diagnosing the presence of renal scar in children with vesicoureteral reflux (VUR): A cross-sectional study

Aim:

To explore the possibility of using urinary biomarkers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) to assess the presence of renal scars in children with Vesicoureteric Reflux (VUR).

Materials and Methods:

This cross-sectional study was conducted in 94 children aged 0–16 years diagnosed with VUR in the Department of Pediatric Surgery, JIPMER. Urinary biomarkers were measured using the enzyme-linked immunosorbent assay kits, normalized with urinary creatinine (Cr) and compared with severity of VUR (low grade [I and II] and high grade [III, IV, and V]), presence or absence of renal scar in VUR patients and severity of renal scar. Independent Student's t-test, Mann–Whitney U-test, and analysis of variance Kruskal–Wallis test were used for comparison, and receiver operating characteristic (ROC) curve analysis for predicting the accuracy of biomarkers in detecting the presence of renal scars.

Results:

The median urinary NGAL (uNGAL) value was higher in children with renal scar (1.49 ng/mL) than those without renal scar (0.58 ng/mL) and was statistically significant (<0.001). Whereas median uNGAL/Cr was higher in children with renal scar (0.07) than those without renal scar (0.03) but was not statistically significant (P = 0.06). Urinary KIM-1 and urinary KIM-1/urinary Cr (uKIM-1/Cr) was not found to be a significant predictor of renal scar. The difference of uNGAL/Cr was comparable between the grades of renal scar but was not statistically significant. On ROC curve analysis, uNGAL had area under the ROC curve (AUC) of 0.769 with 71% of both specificity and sensitivity, whereas uNGAL/Cr was found to be a poor predictor of renal scar with AUC of 0.611, 60% sensitivity, and 61.2% specificity.

Conclusion:

uNGAL can serve as a noninvasive marker for diagnosing the presence of renal scar in children with VUR and a multicentric more extensive cohort study may be needed to strengthen or negate its role.

Potential Novel Biomarkers of Obstructive Nephropathy in Children with Hydronephrosis

Obstructive nephropathy (ON) secondary to the congenital hydronephrosis (HN) is one of the most common causes of chronic kidney disease in children. Neither currently used imaging techniques nor conventional laboratory parameters are sufficient to assess the onset and outcome of this condition; hence, there is a need to prove the usefulness of newly discovered biomarkers of kidney injury in this respect. The purpose of the study was to assess the urinary excretion of alpha-GST, pi-GST, NGAL, and KIM-1 and the serum level of NGAL in children with congenital unilateral hydronephrosis secondary to ureteropelvic junction obstruction. The results were evaluated in relation to severity of HN, the presence of ON, relative function of an obstructed kidney, and the presence of proteinuria. The study comprised 45 children with HN of different grades and 21 healthy controls. Urinary and serum concentrations of biomarkers were measured using specific ELISA kits. Urinary biomarker excretions were expressed as a biomarker/creatinine (Cr) ratio. Patients with the highest grades of HN showed significantly increased values of all measured biomarkers, whereas those with the lowest grades of HN displayed only significant elevation of urinary alpha-GST and the serum NGAL. Urinary NGAL positively correlated with percentage loss of relative function of an obstructed kidney in renal scintigraphy. In patients with proteinuria, significantly higher urinary alpha-GST excretion was revealed as compared to those without this symptom. The ROC curve analysis showed the best diagnostic profile for urinary alpha-GST/Cr and NGAL/Cr ratios in the detection of ON. In conclusion, the results of the study showed that urinary alpha-GST and NGAL are promising biomarkers of ON. Ambiguous results of the remaining biomarkers, i.e., urinary pi-GST and KIM-1, and serum NGAL level may be related to a relatively small study group. Their utility in an early diagnosis of ON should be reevaluated.

Diagnostic accuracy of urinary biomarkers in infants younger than 3 months with urinary tract infection

Purpose

The aim of this study was to evaluate the diagnostic accuracy of urinary biomarkers, such as neutrophil gelatinase-associated lipocalin (uNGAL) and β-2 microglobulin (uB2MG), in early detection of urinary tract infection (UTI) in infants aged <3 months with fever.

Methods

A total of 422 infants aged <3 months (male:female=267:155; mean age, 56.4 days), who were admitted for fever, were retrospectively included in this study. We compared uNGAL and uB2MG between the UTI and non-UTI groups at the time of admission. The sensitivity, specificity, accuracy, and area under the curve (AUC) of uNGAL and uB2MG for use in diagnosing UTI were assessed.

Results

Among 422 patients, 102 (24.2%) were diagnosed with UTI. Levels of uNGAL were higher in the UTI group than in the non-UTI group (366.6 ng/mL vs. 26.9 ng/mL, P<0.001). Levels of uB2MG were not different between the 2 groups. Multivariate analysis revealed that uNGAL was an independent predictive factor for UTI (P=0.033). The sensitivity, specificity, and accuracy were 90.2%, 92.5%, and 91.9% for uNGAL, and 48.0%, 43.8%, and 44.8% for uB2MG, respectively. AUC of uNGAL was 0.942 and that of uB2MG was 0.407.

Conclusion

Accuracy of uNGAL in the diagnosis of UTI is high in febrile infants aged <3 months. uNGAL can help in the early diagnosis and treatment of UTI in infants.

Urine neutrophil gelatinase-associated lipocalin and other biomarkers in infants with urinary tract infection and in febrile controls

BACKGROUND

Urine biomarkers are commonly used in the evaluation of acute kidney injury, and are gaining attention as tools for studying urinary tract infections (UTIs). We analyzed neutrophil gelatinase-associated lipocalin (NGAL) and seven other urine biomarkers to evaluate their usefulness in the diagnosis of UTI in infants.

METHODS

Eight urine biomarkers were analyzed in 108 infants with UTI. Controls were 64 febrile children without UTI and 13 healthy children. Logistic regression and construction of receiver operating characteristic (ROC) curves were performed for UTI patients versus febrile controls for all biomarkers.

RESULTS

The best biomarkers to differentiate between UTI and febrile controls were NGAL and interleukin 8 (IL8). Urine NGAL in absolute concentration and adjusted for creatinine had a sensitivity of 93% and 96% and a specificity of 95% and 100% for diagnosing UTI, with a cut-off concentration of 38 ng/mL and 233 ng/mg respectively.

CONCLUSIONS

Urine biomarkers, particularly NGAL, can aid in the diagnosis of UTI among febrile infants. The results suggest that in infants with fever and high NGAL, UTI is most likely, whereas in infants with fever and low NGAL, other causes of fever should be looked for.

Plasma neutrophil gelatinase-associated lipocalin: a marker of acute pyelonephritis in children

OBJECTIVES

This study was designed to compare the diagnostic accuracy of plasma neutrophil gelatinase-associated lipocalin (NGAL) with procalcitonin (PCT), C-reactive protein (CRP), and white blood cells (WBCs) for predicting acute pyelonephritis (APN) in children with febrile urinary tract infections (UTIs).

MATERIALS AND METHODS

In total, 138 children with febrile UTIs (APN 59, lower UTI 79) were reviewed retrospectively. Levels of NGAL, PCT, CRP, and WBCs in blood were measured on admission. The diagnostic accuracy of the biomarkers was investigated. Independent predictors of APN were identified by multivariate logistic regression analysis.

RESULTS

Receiver operating curve (ROC) analyses showed good diagnostic profiles of NGAL, PCT, CRP, and WBCs for identifying APN [area under the curve (AUC) 0.893, 0.855, 0.879, and 0.654, respectively]. However, multivariate analysis revealed only plasma NGAL level was an independent predictor of APN (P = 0.006). At the best cutoff values of all examined biomarkers for identifying APN, sensitivity (86 %), specificity (85 %), positive predictive value (81 %), and negative predictive value (89 %) of plasma NGAL levels were the highest. The optimal NGAL cutoff value was 117 ng/ml. The positive likelihood ratio [odds ratio (OR) 5.69, 95 % confidence interval (CI) 3.56-8.78], and negative likelihood ratio (OR 0.16, 95 % CI 0.08-0.29) of plasma NGAL for APN diagnosis also showed it seemed to be more accurate than serum PCT, CRP, and WBCs.

CONCLUSION

Plasma NGAL can be more useful than serum PCT, CRP, and WBC levels for identifying APN in children with febrile UTIs.

Neutrophil Gelatinase-Associated Lipocalin Biomarker and Urinary Tract Infections: A Diagnostic Case-Control Study (NUTI Study)

OBJECTIVES

Acute uncomplicated urinary tract infection (UTI) in women is often treated based on symptoms alone. Urinary tract infection symptoms are highly sensitive but lack specificity and result in overuse of antibiotics. We sought to determine if urine neutrophil gelatinase-associated lipocalin (uNGAL) levels in urine can accurately discriminate between UTI and healthy women.

METHODS

We recruited adult women aged 18 to 85 years presenting in the ambulatory setting from November 2014 to January 2016. Cases were defined as women with Centers for Disease Control and Prevention-defined UTI symptoms and a positive urine culture of more than 10 organisms/mL on a midstream clean-catch specimen. Women without UTI symptoms were matched by age and menopausal status as control subjects. Exclusion criteria were no UTIs within 8 weeks, urinary tract anomalies, renal disease, pregnancy, or diabetes. Clean-catch urine samples were obtained for measuring uNGAL, prior to antibiotic treatment of cases. We used Mann-Whitney U test to compare the 2 groups. Receiver operating characteristic curves were plotted to compare the performance of uNGAL to established urinary markers.

RESULTS

We enrolled 50 UTI cases and 50 control subjects. Urine NGAL levels were higher in the UTI group than in the control subjects (P < 0.0001). Using a cutoff of 23.9 ng/mL, NGAL achieved 98% sensitivity and 100% specificity. The receiver operating characteristic curve had an area under the curve of 0.97 (95% confidence interval, 0.93-1.00), which was significantly high and showed that uNGAL can identify UTI.

CONCLUSIONS

Urine NGAL has the potential as a biomarker for diagnosing UTIs in adult women.

Urinary L-FABP as a marker of vesicoureteral reflux in children: could it also have a protective effect on the kidney?

PURPOSE

Liver-type fatty acid-binding protein is a small cytoplasmic protein which is expressed in the human renal proximal tubular epithelium and synthesized in response to renal tubular injury. The aim of the present study was to investigate the importance of urinary liver-type fatty acid-binding protein levels in children who diagnosed with vesicoureteral reflux.

METHODS

Fifty-six patients with vesicoureteral reflux and 51 healthy controls were enrolled to the study. The cases were divided into three groups as follows: group A-the controls, group B-the patients who had renal parenchymal scarring and group C-the patients who had no scarring. Urinary liver-type fatty acid-binding protein was measured by enzyme-linked immunosorbent assay method. Creatinine was measured by modified Jaffe method, protein was measured by turbidimetric method, and urine density was determined by using the "falling drop" procedure.

RESULTS

Urinary liver-type fatty acid-binding protein and urinary liver-type fatty acid-binding protein/creatinine levels were significantly higher in the whole patient group than in the controls (p = 0.016, 0.006). Significant differences were also determined by comparing the three groups (p = 0.015, 0.014), and those levels were found as significantly higher in group C.

CONCLUSION

Urinary liver-type fatty acid-binding protein was considered to be helpful for the diagnosis of vesicoureteral reflux, and also it might contribute to understand the mechanisms causing scar tissue formation especially for the patients who had vesicoureteral reflux. Further clinical and experimental investigations are required to elucidate in detail the physiology of liver-type fatty acid-binding protein.

Role of new biomarkers for predicting renal scarring in vesicoureteral reflux: NGAL, KIM-1, and L-FABP

BACKGROUND

Reflux nephropathy is the most serious complication of vesicoureteral reflux (VUR). The aim of this study was to assess the role of urinary levels of neutrophil-gelatinase-associated lipocalin (NGAL),kidney injury molecule-1 (KIM-1), and liver-type fatty-acid-binding protein (L-FABP) in the early diagnosis of reflux nephropathy in patients with VUR.

METHODS

This study assessed 123 patients with primary VUR and 30 healthy children as a control group. The children were divided into five groups: Group A, patients with VUR and renal parenchymal scarring (RPS); Group B, patients with VUR and without RPS; Group C, patients with RPS and resolved VUR; Group D, patients with resolved VUR and without RPS; Group E, healthy reference group.

RESULTS

Median urinary NGAL (uNGAL)/Creatinine (Cr) was significantly higher in patients with than those without RPS and the control group (p = 0.0001). Median uKIM-1/Cr was similar in all groups (p = 0.417). Median uL-FABP/Cr was significantly higher in patients with RPS than in the reference group (p < 0.05).

CONCLUSIONS

Urinary NGAL levels may be used as a noninvasive diagnostic marker for predicting renal scarring in reflux nephropathy.

Early Markers of Tubulointerstitial Fibrosis in Children With Idiopathic Nephrotic Syndrome: Preliminary Report

Tubulointerstitial fibrosis and tubular atrophy play a crucial role in the pathogenesis of chronic kidney disease (CKD). They are also major determinants in chronic kidney disease development and progression in patients with primary renal diseases characterized by persistent or recurrent proteinuria. The purpose of the study was to assess urinary excretion of alpha-glutathione S-transferase (alpha-GST), pi-glutathione S-transferase (pi-GST), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and serum NGAL level in children with idiopathic nephrotic syndrome (INS).

PATIENTS AND METHODS

the study group comprised of 39 children with INS and the control group consisted of 20 healthy children. A total of 23 patients were affected with steroid-dependent nephrotic syndrome (SDNS) and 16 with steroid-resistant nephrotic syndrome (SRNS). In the majority of patients, a histopathologic examination revealed minimal change disease (MCD)-25 (64%). Focal segmental glomerulosclerosis (FSGS), mesangioproliferative glomerulonephritis (MesPGN), membranoproliferative glomerulonephritis (MPGN), and membranous glomerulonephritis (MGN) were diagnosed in 4 (10.3 %), 6 (15.5%), 2 (5.1%), and 2 (5.1%) children, respectively. Urinary alpha-GST, urinary pi-GST, urinary KIM-1, and urinary and serum NGAL concentrations were measured using specific enzyme-linked immunosorbent assay. The urinary results were expressed in nanograms per milligram of creatinine (ng/mg).

RESULTS

The authors observed significantly higher levels of urinary alpha-GST/creatinine ratio (P = 0.03), urinary KIM-1/creatinine ratio (P < 0.02), serum NGAL level (P < 0.01), and urinary NGAL/creatinine ratio (P = 0.02) in children with INS compared with controls. The median values of urinary pi-GST/creatinine ratio in children with INS and controls did not differ significantly. In children with SRNS, the median values of urinary NGAL/creatinine ratio (P = 0.02) and urinary KIM-1/creatinine ratio (P = 0.02) were significantly higher compared with children with SDNS. The authors noted significant positive correlation between KIM-1/creatinine ratio and proteinuria (r = 0.56, P < 0.05). The analysis of alpha-GST/creatinine ratio, pi-GST/creatinine ratio, sNGAL, and uNGAL/creatinine ratio concerning the histopathologic examination, the duration of the disease, and number of relapses did not show any significant differences.

CONCLUSIONS

1. Both children with SDNS and those with SRNS were characterized by increased tubular injury marker levels. 2. Patients with SRNS and higher proteinuria are more susceptible to early kidney damage.

Plasma neutrophil gelatinase-associated lipocalin predicts acute pyelonephritis in children with urinary tract infections

BACKGROUND

The identification of acute pyelonephritis (APN) is still a challenge.

METHODS

Patients admitted for their first urinary tract infection (UTI) were enrolled. Plasma neutrophil gelatinase-associated lipocalin (NGAL) levels were measured at admittance and after treatment. Laboratory, clinical, and imaging results were compared between children with and without APN.

RESULTS

A total of 123 patients were enrolled (53 APN and 70 lower UTI). After adjusting for age and gender, plasma NGAL levels were higher in the APN group than in the lower UTI group (233 (129-496) ng/ml vs. 71 (50.8-110) ng/ml, P < 0.001). NGAL levels were correlated with the serum levels of leukocytes, C-reactive protein, and creatinine, as well as fever duration (P < 0.05). Multivariable analysis revealed that log-transformed plasma NGAL was an independent predictor of APN (P < 0.05). Receiver operating curve analysis showed a good diagnostic profile of NGAL for identifying APN (area under the curve 0.864) with a best cut-off value of 102.5 ng/ml. The NGAL levels in both two groups decreased after treatment compared to levels before treatment (P < 0.001).

CONCLUSION

Plasma NGAL can be a sensitive predictor for identifying APN and monitoring the treatment response of pediatric UTI.

Urinary neutrophil gelatinase-associated lipocalin (NGAL) might be an independent marker for anticipating scar formation in children with acute pyelonephritis

INTRODUCTION

Urinary tract infections (UTIs) are the most serious common bacterial infections among young children. It may affect kidneys that classified as acute pyelonephritis (APN) and may lead to renal parenchymal involvement and scarring with high prevalence rate (15%-60%) among children. This study aimed to assess the urinary concentration of neutrophil gelatinase-associated lipocalin (NGAL) in patients with APN to diagnose those with potency to scar formation.

PATIENTS AND METHODS

Children who were admitted with a diagnosis of APN were enrolled and divided into two groups; APN with scar and APN without scar. Urinary levels of NGAL and its ratio to creatinine (Cr) levels were measured in the acute phase of infection. A receiver operating characteristic (ROC) curve was generated to allow calculation of cut-off values.

RESULTS

Fifty-four children were enrolled across the 2 groups: group 1 consisted of 16 patients (all female); group 2 consisted of 38 children (36 female and 2 male). Urinary levels of NGAL were significantly higher in APN with scar than in APN without scar (P = 0.037). For comparison of groups 1 and 2, the cut-off values were measured as 7.32 ng/ml, sensitivity; 81.3% and specificity; 66%.

CONCLUSION

Evaluation of urinary NGAL levels may help us to identify children with APN who are at risk of developing renal scarring.

The diagnosis of febrile urinary tract infection in children may be facilitated by urinary biomarkers

BACKGROUND

We prospectively assessed the feasibility of two urinary markers of renal injury as potential diagnostic tests for acute febrile urinary tract infection (UTI) and subsequent renal scarring.

METHODS

The patient cohort comprised children aged 0 to 4 years who visited the emergency room. The children were divided into three groups, namely, a febrile UTI (fUTI), febrile control (FC) and a non-febrile control (NFC) group, respectively, which were matched for sex and age. An enzyme-linked immunosorbent assay for neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) was performed on urine collected from each child. The urine levels of both markers were compared between the three groups, and the diagnostic accuracy was determined based on the area under the receiver-operator characteristic curve (AUC). In the fUTI group, the predictability of subsequent renal scarring was assessed by associating urinary levels with dimercaptosuccinic acid findings 6 months after an UTI episode.

RESULTS

Significantly elevated levels of urinary NGAL and KIM-1 were observed in the fUTI group, as well as with increased urine esterase, serum C-reactive protein, and pyuria. The AUC was 72 % for KIM-1 and 96 % for NGAL. The AUC of KIM-1 for the prediction of scarring was 71 % (p < 0.05).

CONCLUSIONS

The diagnosis of febrile UTI and the prediction of subsequent scarring may be facilitated by assaying urine biomarkers with acceptable accuracy.

Predictive value of urinary and serum biomarkers in young children with febrile urinary tract infections

BACKGROUND

Early predictive biomarkers for the diagnosis and management of febrile urinary tract infections (UTIs) can be valuable diagnostic tools in children.

METHODS

The study cohort comprised 73 pediatric patients with febrile UTIs [46 with acute pyelonephritis (APN) and 27 with lower UTIs] and 56 healthy children. Urine neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (uKIM-1) levels and serum cystatin C (sCysC) levels were measured.

RESULTS

The uNGAL/creatinine (Cr) and uKIM-1/Cr levels were higher in the UTI group than in the controls (P < 0.05). uNGAL/Cr and sCysC levels were higher in patients with APN than in those with lower UTIs (P < 0.05). uNGAL/Cr levels in both the APN and UTI groups decreased following the administration of antibiotics compared to those before treatment (P < 0.05). The uNGAL/Cr level was correlated with serum levels of white blood cells, C-reactive protein, CysC and with uKIM-1/Cr (P < 0.05). uKIM-1/Cr was also correlated with sCysC (P < 0.05). Receiver operating curve analyses showed good diagnostic profiles of uNGAL/Cr and uKIM-1/Cr for identifying UTIs [area under the curve (AUC) 0.9 and 0.66, respectively) and of uNGAL/Cr and sCysC for predicting APN (AUC 0.78 and 0.72, respectively).

CONCLUSIONS

Our results suggest that uNGAL, uKIM-1 and sCysC levels may be useful for predicting and managing febrile UTIs in children.

A rapid plasma neutrophil gelatinase-associated lipocalin assay for diagnosis of acute pyelonephritis in infants with acute febrile urinary tract infections: a preliminary study

In infants with febrile urinary tract infection (UTI), the accurate rapid diagnosis of acute pyelonephritis (APN) would be valuable because early aggressive treatment reduces the risk of renal scarring. The objective of the study was to evaluate whether rapid plasma neutrophil gelatinase-associated lipocalin (NGAL) assay could be used as a diagnostic biomarker of renal parenchymal injury in infants with acute febrile UTI to distinguish APN at the bedside. This prospective observational study included 47 infants, who were admitted with a first episode of acute febrile UTI. Total UTI group was divided into the Cortical defect (UTI-CD, n = 24) group and Non-cortical defect (UTI-ND, n = 23) group, according to the result of renal scan. For the Control group, 15 infants who presented a febrile episode without any focus of bacterial infection were included. On admission, the median NGAL level (106.5 [60-476] ng/mL) in the UTI-CD group was significantly higher than that (60 [60-196] ng/mL) in the UTI-ND group and that (60 [60-197] ng/mL) in the Control group and was significantly decreased to 60 [60-306] ng/mL after an antibiotic treatment. The area under the receiver operating characteristic curves was 0.748 (95 % CI, 0.610-0.887; P = 0.003) for NGAL levels and 0.724 (95 % CI, 0.579-0.868; P = 0.009) for CRP levels. The best cutoff of NGAL level for detection of APN was founded to be 61.0 ng/mL (sensitivity, 75.0 %; specificity, 78.3 %). Although not a stand-alone test, the rapid determination of plasma NGAL level provides valuable information quickly, concerning the distinction of APN, for determining the clinical course of acute febrile UTI.

Urinary Measurement of Neutrophil Gelatinase Associated Lipocalin and Kidney Injury Molecule-1 Helps Diagnose Acute Pyelonephritis in a Preclinical Model

Background. The study assessed whether measurement of urinary biomarkers of acute kidney injury could be helpful in diagnosing acute pyelonephritis and subsequent scarring. Method. Escherichia coli J96 (0.3 mL inoculum containing 1 × 10⁹/mL) was directly injected into the renal cortex of 3-week-old female Sprague Dawley rats (n = 20), with saline substituted in a control group (n = 10). Following the injection, urine was collected 2, 7, 14, 28, and 42 days after injection. Urinary neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (Kim-1), and interleukin-18 were quantitatively measured using enzyme-linked immunosorbent assay (ELISA). The levels of the biomarkers were adjusted for creatinine. Time course changes within a group or between the groups were compared. Correlation analysis was performed to understand the relationship between urinary levels and histological scarring. Results. Significantly elevated urinary NGAL was evident at two and seven days after injection, and Kim-1 was elevated at two days after injection. Receiver operating characteristic analyses confirmed the sensitivity of these markers at these times. No urinary marker at acute stage of APN was correlated with the amount of future scarring, negating their predictive value. Conclusion. Urinary NGAL and Kim-1 could be helpful in diagnosing febrile urinary tract infection in children.

Urinary NGAL, cystatin C, β2-microglobulin, and osteopontin significance in hydronephrotic children

BACKGROUND

Ureteropelvic junction obstruction (UPJO) accounts for 35 % of all congenital hydronephrosis cases. The challenge in managing childhood hydronephrosis is to distinguish obstructive from nonobstructive cases and, thereby, identify patients requiring surgical intervention. This study aimed to examine four urinary proteins as potential biomarkers of obstruction in hydronephrosis.

METHODS

Urine samples from 24 children with UPJO were collected pre-, peri-, and postoperatively, together with urine samples from healthy children. Neutrophil gelatinase-associated lipocalin (NGAL), cystatin C (CyC), β2-microglobulin (β2-M), and osteopontin (OPN) in the samples were measured simultaneously using multiplex sandwich immunoassay technology.

RESULTS

Compared with controls, NGAL and β2-M were significantly increased in urine from patients with obstructed kidneys at the time of surgery. This increase was followed by a decrease and stabilization to the same level as that of the controls. Furthermore, age was negatively correlated with preoperative urinary concentrations of CyC, β2-M, and OPN.

CONCLUSIONS

This study confirms increased concentrations of NGAL and β2-M in urine from obstructed kidneys and should be tested in larger studies to ascertain their ability to identify obstruction and to determine the importance of age-adjusted reference values.