Therapy Insight: what nephrologists need to know about primary vesicoureteral reflux

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.

Developmental pathology of congenital kidney and urinary tract anomalies

Congenital anomalies of the kidneys or lower urinary tract (CAKUT) are the most common causes of renal failure in children and account for 25% of end-stage renal disease in adults. The spectrum of anomalies includes renal agenesis; hypoplasia; dysplasia; supernumerary, ectopic or fused kidneys; duplication; ureteropelvic junction obstruction; primary megaureter or ureterovesical junction obstruction; vesicoureteral reflux; ureterocele; and posterior urethral valves. CAKUT originates from developmental defects and can occur in isolation or as part of other syndromes. In recent decades, along with better understanding of the pathological features of the human congenital urinary tract defects, researchers using animal models have provided valuable insights into the pathogenesis of these diseases. However, the genetic causes and etiology of many CAKUT cases remain unknown, presenting challenges in finding effective treatment. Here we provide an overview of the critical steps of normal development of the urinary system, followed by a description of the pathological features of major types of CAKUT with respect to developmental mechanisms of their etiology.

Genome-wide linkage and association study implicates the 10q26 region as a major genetic contributor to primary nonsyndromic vesicoureteric reflux

Vesicoureteric reflux (VUR) is the commonest urological anomaly in children. Despite treatment improvements, associated renal lesions – congenital dysplasia, acquired scarring or both – are a common cause of childhood hypertension and renal failure. Primary VUR is familial, with transmission rate and sibling risk both approaching 50%, and appears highly genetically heterogeneous. It is often associated with other developmental anomalies of the urinary tract, emphasising its etiology as a disorder of urogenital tract development. We conducted a genome-wide linkage and association study in three European populations to search for loci predisposing to VUR. Family-based association analysis of 1098 parent-affected-child trios and case/control association analysis of 1147 cases and 3789 controls did not reveal any compelling associations, but parametric linkage analysis of 460 families (1062 affected individuals) under a dominant model identified a single region, on 10q26, that showed strong linkage (HLOD = 4.90; ZLRLOD = 4.39) to VUR. The ~9Mb region contains 69 genes, including some good biological candidates. Resequencing this region in selected individuals did not clearly implicate any gene but FOXI2, FANK1 and GLRX3 remain candidates for further investigation. This, the largest genetic study of VUR to date, highlights the 10q26 region as a major genetic contributor to VUR in European populations.

Analysis of the IL-10, IL-12, and TNF-α Gene Polymorphisms in Patients With Vesicoureteral Reflux Among the Southeast Iranian Population

Background

Vesicoureteral reflux (VUR) is a common childhood disorder that is characterized by the abnormal movement of urine from the bladder into the ureters or kidneys.

Objectives

The aim of this study was to determine whether the genetic polymorphisms of the IL-10, IL-12, and TNF-α genes are involved in the development of VUR.

Patients and Methods

The tetra amplification mutation refractory system-polymerase chain reaction (Tetra-ARMS PCR) was applied to analyze the four polymorphic sites of the IL-10AG-1082, IL-10CA597, IL-12CA1188, and TNF308GA genes in 124 VUR children and 110 healthy controls.

Results

A significant, highly increased risk of VUR disease was found for the CA, AA, and combined genotypes of IL-10CA597 (OR = 5.2, 95% CL: 1.80 - 18.25; P = 0.0006, OR = 9.1, 95% CL: 1.11 - 122.75; P = 0.02, OR = 5.3, 95% CL: 1.82 - 18.61; P = 0.00052, respectively); the AG, GG, and AG + GG genotypes of IL-10AG-1082 (OR = 12.8, 95% CL; 2.9 - 113.9; P = 0.00003, OR = 12.62, 95% CL: 2.93 - 114.53; P = 0.00003, respectively); and the AA genotype of IL-12 (AA, OR = 0.19, 95% CL: 0.5 - 0.55; P = 0.0006). The frequency of the C allele in both IL-10CA and IL-12CA was greater in patients with VUR than in the healthy controls. No association was found between TNF308GA and the risk of VUR.

Conclusions

The results demonstrated significant associations between the IL-10 (AG-1089, IL-10CA) and IL-12 (AA) gene polymorphisms and a highly increased risk of VUR.

Postoperative ureteral obstruction after endoscopic treatment for vesicoureteral reflux

Purpose

We undertook this study to evaluate the incidence, risk factors, management, and outcome of postoperative ureteral obstruction after endoscopic treatment for vesicoureteral reflux (VUR).

Materials and Methods

Ninety patients undergoing endoscopic treatment for VUR were retrospectively reviewed and classified into two groups according to ureteral obstruction: the nonobstruction group (83 cases, 122 ureters; mean age, 7.0±2.8 years) and the obstruction group (7 cases, 10 ureters; mean age, 6.2±8.1 years). We analyzed the following factors: age, sex, injection material, laterality, voiding dysfunction, constipation, renal scarring, preoperative and postoperative ultrasound findings, endoscopic findings, injection number, and injection volume. Additionally, we reviewed the clinical manifestations, natural course, management, and outcome of ureteral obstruction after endoscopic treatment.

Results

The incidence of ureteral obstruction after endoscopic treatment was 7.6% (10/132 ureters). The type of bulking agent used and injection volume tended to be associated with ureteral obstruction. However, no significant risk factors for obstruction were identified between the two groups. Three patients showed no symptoms or signs after the onset of ureteral obstruction. Most of the patients with ureteral obstruction experienced spontaneous resolution within 1 month with conservative therapy. Two patients required temporary ureteral stents to release the ureteral obstruction.

Conclusions

In our experience, the incidence of ureteral obstruction was slightly higher than in previous reports. Our study identified no predictive risk factors for developing ureteral obstruction after endoscopic treatment. Although most of the ureteral obstructions resolved spontaneously within 1 month, some cases required drainage to relieve symptoms or to prevent renal function deterioration.

Assessment of cystatin C and cystatin C-based GFR formulas in reflux nephropathy

OBJECTIVE

Early identification of reflux nephropathy (RN) could reduce the frequency of chronic kidney disease (CKD) caused by vesicoureteral reflux (VUR). We aimed to assess whether cystatin C has value for determining RN in children with VUR.

MATERIALS AND METHODS

Ninety-three children with VUR were classified into two groups according to the presence of renal parenchymal scarring (RS). Patients with RS were divided into three subgroups according to scar grade. Serum cystatin C, serum creatinine (Scr) and urine creatinine were measured. eGFR values of the patients were calculated with Scr-based, cystatin C-based and combined formulas.

RESULTS

Cystatin C was significantly higher in patients with RS than patients without RS and declined in parallel with grade of RS (p = 0.01). Scr was not significant in patients with and without RS. It was only significant between mild and severe scar subgroups (p < 0.05). All eGFR values were lower in RS (+) patients compared with RS (-) patients. All eGFR equations were negatively correlated with grade of RS (p < 0.05).

CONCLUSION

Cystatin C could be a useful marker for identifying the risk and severity of RN in patients with VUR. Renal functions could be more accurately determined with Scr-cystatin C combined eGFR equations.

Does routine ultrasound change management in the follow-up of patients with vesicoureteral reflux?

INTRODUCTION

Children with vesicoureteral reflux (VUR) usually need a renal ultrasound (RUS). There is little data on the role of follow-up RUS in VUR. We evaluated the impact of follow-up RUS on the change in clinical management in patients with VUR.

METHODS

We prospectively analyzed children with a previous diagnosis of VUR seen in the outpatient clinic with a routine follow-up RUS within 4 months. Variables collected included: demographic data, VUR history, dysfunctional voiding symptoms and concurrent ultrasound findings. Change in management was defined as addition of new medication, nurse counselling, surgery or further investigations.

RESULTS

The study included 114 consecutive patients. The mean patient age was 4.5 years old, mean age of VUR diagnosis was 1.7 years, with average follow-up of 2.8 years. A change in management with stable RUS occurred in 14 patients, in which the change included ordering a DMSA in 9, nurse counselling for dysfunctional voiding in 3, and booking surgery in 2 patients. Change on RUS was seen in 4 patients. Multivariable analysis showed that history of urinary tract infection (UTI) since the last follow-up visit was more significant than RUS findings.

CONCLUSIONS

The RUS findings in most patients followed for VUR remain stable or with minimal changes. The variable showing a significant effect on change in management in our study was history of UTI since the last follow-up visit rather than RUS findings. The value of follow-up RUS for children with VUR may need to be revisited.

A new genome scan for primary nonsyndromic vesicoureteric reflux emphasizes high genetic heterogeneity and shows linkage and association with various genes already implicated in urinary tract development

Primary vesicoureteric reflux (VUR), the retrograde flow of urine from the bladder toward the kidneys, results from a developmental anomaly of the vesicoureteric valve mechanism, and is often associated with other urinary tract anomalies. It is the most common urological problem in children, with an estimated prevalence of 1–2%, and is a major cause of hypertension in childhood and of renal failure in childhood or adult life. We present the results of a genetic linkage and association scan using 900,000 markers. Our linkage results show a large number of suggestive linkage peaks, with different results in two groups of families, suggesting that VUR is even more genetically heterogeneous than previously imagined. The only marker achieving P < 0.02 for linkage in both groups of families is 270 kb from EMX2. In three sibships, we found recessive linkage to KHDRBS3, previously reported in a Somali family. In another family we discovered sex-reversal associated with VUR, implicating PRKX, for which there was weak support for dominant linkage in the overall data set. Several other candidate genes are suggested by our linkage or association results, and four of our linkage peaks are within copy-number variants recently found to be associated with renal hypodysplasia. Undoubtedly there are many genes related to VUR. Our study gives support to some loci suggested by earlier studies as well as suggesting new ones, and provides numerous indications for further investigations.

Lower urinary tract development and disease

Congenital anomalies of the lower urinary tract (CALUT) are a family of birth defects of the ureter, the bladder, and the urethra. CALUT includes ureteral anomaliesc such as congenital abnormalities of the ureteropelvic junction (UPJ) and ureterovesical junction (UVJ), and birth defects of the bladder and the urethra such as bladder-exstrophy-epispadias complex (BEEC), prune belly syndrome (PBS), and posterior urethral valves (PUVs). CALUT is one of the most common birth defects and is often associated with antenatal hydronephrosis, vesicoureteral reflux (VUR), urinary tract obstruction, urinary tract infections (UTI), chronic kidney disease, and renal failure in children. Here, we discuss the current genetic and molecular knowledge about lower urinary tract development and genetic basis of CALUT in both human and mouse models. We provide an overview of the developmental processes leading to the formation of the ureter, the bladder, and the urethra, and different genes and signaling pathways controlling these developmental processes. Human genetic disorders that affect the ureter, the bladder and the urethra and associated gene mutations are also presented. As we are entering the postgenomic era of personalized medicine, information in this article may provide useful interpretation for the genetic and genomic test results collected from patients with lower urinary tract birth defects. With evidence-based interpretations, clinicians may provide more effective personalized therapies to patients and genetic counseling for their families.

Heterozygous non-synonymous ROBO2 variants are unlikely to be sufficient to cause familial vesicoureteric reflux

ROBO2, the receptor of SLIT2, is one of many genes/proteins that regulate the outgrowth of the ureteric bud, which is the first step in the development of the metanephric urinary system. Non-synonymous variants in ROBO2 have been found in a small proportion of patients with primary vesicoureteric reflux (VUR) in various countries. Here we sequenced 1 kb of promoter and all exons of ROBO2b with intronic margins in 227 index cases with primary VUR in an Irish population and found 55 variants, of which 20 were novel. We assessed the variants for evolutionary conservation and investigated novel and uncommon known conserved variants in 23 further index cases and family members of all index cases (to check for segregation with VUR), and then in healthy controls if we found segregation of the variants with VUR. Apart from one non-synonymous variant that was previously found in controls, we did not find any of the six other previously reported non-synonymous variants, but found four new non-synonymous variants. Of those, only two segregated with the disorder (p.Pro522Thr and p.Val799Ile). The former was not present in any of 592 healthy controls; the latter was present in one control. There are now 35 reported non-synonymous coding variants of ROBO2b. The predicted pathogenicity of those that have so far been found exclusively in VUR patients does not differ from that predicted for those variants also found in controls. Thus, our finding does not completely rule out that some variants may be the sole cause of VUR, but it is clear from the overall frequency that most of them cannot be. However, it is possible that some of these variants may cause VUR in combination with a mutation in another gene.

Prospective evaluation of healthy Ragdoll cats for chronic kidney disease by routine laboratory parameters and ultrasonography

Ragdoll breeder organisations often forewarn Ragdoll cat owners that renal problems may develop as a result of polycystic kidney disease (PKD), chronic interstitial nephritis, familial renal dysplasia or nephrocalcinosis. Healthy Ragdoll and non-Ragdoll cats were prospectively evaluated by measuring serum creatinine and urea concentrations, routine urinalysis and abdominal ultrasonography. All Ragdoll cats also underwent genetic PKD testing. One hundred and thirty-three Ragdoll and 62 control cats were included. Ragdoll cats had significantly lower serum urea concentrations and higher urinary specific gravity. However, median creatinine concentration, median urinary protein-to-creatinine ratio, and the proportion of cats with serum creatinine or urea concentration exceeding the reference interval did not differ. One or more renal ultrasonographical changes were detected in 66/133 (49.6%) Ragdoll and in 25/62 (40%) control cats. Ragdoll cats showed significantly more frequent segmental cortical lesions (7.5% versus 0%), abnormal renal capsule (19.5% versus 8%) and echogenic urine (51.9% versus 25.8%). Chronic kidney disease (CKD) was ultrasonographically suspected in 7/133 (5.3%) Ragdoll and in none of the control cats, which approached significance. Laboratory parameters confirmed kidney dysfunction only in 1/7 of these Ragdoll cats. All Ragdoll cats were PKD negative. In conclusion, first, breed-specific serum creatinine reference intervals are not likely required for Ragdoll cats. Second, renal ultrasonographical abnormalities are common, both in Ragdoll and non-Ragdoll cats. Third, healthy young Ragdoll cats are uncommonly affected by PKD and CKD, but an increased susceptibility of Ragdoll cats to develop CKD cannot be excluded. Finally, Ragdoll cats are predisposed to segmental cortical lesions, which may indicate renal infarction or cortical scarring.

Febrile urinary tract infections in young children: recommendations for the diagnosis, treatment and follow-up

We report the recommendations for the diagnosis, treatment, imaging evaluation and use of antibiotic prophylaxis in children with the first febrile urinary tract infection, aged 2 months to 3 years. They were prepared by a working group of the Italian Society of Pediatric Nephrology after careful review of the available literature and a consensus decision, when clear evidence was not available.

CONCLUSION

These recommendations are endorsed by the Italian Society of Pediatric Nephrology. They can also be a tool of comparison with other existing guidelines in issues in which much controversy still exists.

Electrolyte disturbances in acute pyelonephritis

The aim of this study was to determine whether renal unresponsiveness to aldosterone associated with hyperkalemia is present in infants with acute pyelonephritis in the absence of significant urinary tract anomalies and to describe the clinical characteristics of patients presenting an inadequate renal response to hyperkalemia. The patient cohort comprised 113 infants with acute pyelonephritis (APN), based on the criteria of a temperature >38°C and significant bacteriuria. Serum and urine electrolytes, creatinine, osmolality, and renal tubular function tests were performed at diagnosis. The findings were compared to those present in 75 children who had fever without significant bacteriuria. Hyperkalemia (>5.5 mmol/L) was observed in infants with an APN diagnosis, who exhibited a lower transtubular potassium concentration gradient (TTKG) and a higher fractional sodium excretion. We defined inadequate renal response to hyperkalemia as the combination of hyperkalemia and TTKG below the normal range established for the age of the subject. Infants presenting an inadequate response to hyperkalemia were younger and associated more frequently with an APN diagnosis. This alteration could be explained by the renal interstitial inflammation present in acute pyelonephritis and the immaturity of the renal tubular responsiveness to aldosterone due to infancy in the absence of urinary tract infection or obstruction.

Congenital anomalies of kidney and urinary tract

Congenital anomalies of the kidney and urinary tract anatomy (CAKUT) are common in children and represent approximately 30% of all prenatally diagnosed malformations. CAKUT is phenotypically variable and can affect the kidney(s) alone and/or the lower urinary tract. The spectrum includes more common anomalies such as vesicoureteral reflux and, rarely, more severe malformations such as bilateral renal agenesis. In young children, congenital anomalies are the leading cause of kidney failure and for kidney transplantation or dialysis. CAKUT can also lead to significant renal problems in adulthood and may present itself with hypertension and/or proteinuria. Congenital renal anomalies can be sporadic or familial, syndromic (also affecting nonrenal or non-urinary tract tissues), or nonsyndromic. Genetic causes have been identified for the syndromic forms and have shed some light into the molecular mechanisms of kidney development in human beings. The genetic causes for the more common nonsyndromic forms of CAKUT are unknown. The role of prenatal interventions and postnatal therapies as well as the benefits of screening affected individuals and their family members are not clear.

Teaching bioethics: the tale of a "soft" science in a hard world

BACKGROUND

Although bioethics is considered essential to the practice of medicine, medical students often view it as a "soft" subject that is secondary in importance to the other courses in their basic science and clinical curriculum. This perspective may be a consequence of the heavy reliance on students' aptitude in the quantitative sciences as a criterion for entry into medical school and as a barometer of academic success after admission. It is exacerbated by the widespread impression that bioethics is imprecise and culturally relativistic.

SUMMARY

In an effort to redress this imbalance, we propose an approach to teaching bioethics to medical students which emphasizes that the intellectual basis and the degree of certainty of knowledge is comparable in all medical subjects ranging from basic science courses to clinical rotations to bioethics tutorials.

CONCLUSIONS

Adopting these pedagogical steps may promote greater integration of the various elements-bioethics and clinical science-in the medical school curriculum.

Evaluation of dynamic contrast-enhanced MRI in detecting renal scarring in a rat injury model

PURPOSE

To create a reliable rat model with small renal cortical scars and evaluate the accuracy and sensitivity of dynamic contrast-enhanced MRI in detecting the kinds of lesions that are associated with reflux nephropathy.

MATERIALS AND METHODS

In 16 rats, three unilateral renal cortical lesions were created using either electrocautery or pure alcohol with the contralateral kidney serving as control. MRI on a 1.5 Tesla GE Signa was performed 10-14 days after surgery. After bolus injection of 0.2 mM/Kg Gd-DTPA, sequential MRI acquisitions were performed using a 4-inch quadrature birdcage coil. Renal and scar volumes and pathology were compared after scanning and killing.

RESULTS

Of the 48 points of injury, 40 (83%) in the 16 rats were detected grossly. Under microscopy, 36 injuries (75%) were detected on mid-kidney cross-sections. The average lesion was 4.2 mm(3) corresponding to 0.5% of the kidney volume. Using pathological findings as the gold standard, the sensitivity and specificity of scar detection using MRI was 69% and 93%, respectively.

CONCLUSION

A rat model was created to demonstrate the sensitivity of dynamic contrast-enhanced MRI for detecting renal scars. Alcohol and electrocautery created reliable renal scars that were confirmed pathologically. MRI detected these lesions that averaged 4.2 mm(3) (0.5% total renal volume) with sensitivity and specificity of 69% and 93%, respectively.

Bladder Dysfunction in Infants with Primary Vesicoureteric Reflux

There is growing evidence that bladder dysfunction is a negative prognostic factor for spontaneous resolution of vesicoureteric reflux (VUR). This study evaluated the prevalence of urodynamic abnormalities in infants with primary VUR who were referred over a 4-year period. The urodynamic evaluations and medical records of 54 infants with primary VUR (79 ureters with reflux) were reviewed prospectively. Urodynamic dysfunction was observed in 46.3% ( n = 25) of infants with primary VUR; 35.2% ( n = 19) had a low bladder capacity and 11.1% ( n = 6) had a large bladder capacity. All infants with large bladder capacities also had high grade (IV-V) VUR. In conclusion, there was a close relationship between bladder dysfunction and primary VUR. For that reason, urodynamic testing of infants with primary VUR should be performed as part of routine clinical evaluations.

Update on childhood urinary tract infection and vesicoureteral reflux

Urinary tract infection (UTI) is a leading cause of serious bacterial infection in young children. Vesicoureteral reflux (VUR), a common pediatric urologic disorder, is believed to predispose to UTI, and both are associated with renal scarring. The complex interaction of bacterial virulence factors and host defense mechanisms influence renal damage. However, some renal parenchymal abnormalities associated with VUR are noninfectious in origin. Long-term, renal parenchymal injury may be associated with hypertension, pregnancy complications, proteinuria, and renal insufficiency. Optimal management of VUR and UTI is controversial because of the paucity of appropriate randomized controlled trials; there is a need for well-designed studies. The recently launched Randomized Intervention for children with VesicoUreteral Reflux (RIVUR) study hopefully will provide insight into the role of antimicrobial prophylaxis of UTI in children with VUR.

Vesicoureteral reflux, reflux nephropathy, and end-stage renal disease

Objective. To review the contribution of vesicoureteral reflux and reflux nephropathy to end-stage renal disease. Data Source. Published research articles and publicly available registries. Results. Vesicoureteral reflux (VUR) is commonly identified in pediatric patients and can be associated with reflux nephropathy (RN), chronic kidney disease (CKD), and rarely end-stage renal disease (ESRD). Patients with reduced GFR, bilateral disease, grade V VUR, proteinuria, and hypertension are more likely to progress to CKD and ESRD. Because progression to ESRD is rare in VUR and often requires many decades to develop, there are limited prospective, randomized, controlled trials available to direct therapy to prevent progression to ESRD. Conclusions. Identification of patients with increased risk of progression to CKD and ESRD should be the goal of clinical, biochemical, and radiological evaluation of patients with VUR. Treatment of patients with VUR should be directed at preventing new renal injury and preserving renal function.

Antibiotic prophylaxis for children with primary vesicoureteral reflux: where do we stand today?

The main goal of the management of vesicoureteral reflux (VUR) is prevention of recurrent urinary tract infections (UTIs), and thereby prevention of renal parenchymal damage possibly ensuing from these infections. Long-term antibiotic prophylaxis is common practice in the management of children with VUR, as recommended in 1997 in the guidelines of the American Urological Association. We performed a systematic review to ascertain whether antibiotics can be safely discontinued in children with VUR and whether prophylaxis is effective in the prevention of recurrent UTIs and renal damage in these patients. Several uncontrolled studies indicate that antibiotic prophylaxis can be discontinued in a subset of patients, that is, school-aged children with low-grade VUR, normal voiding patterns, kidneys without hydronephrosis or scars, and normal anatomy of the urogenital system. Furthermore, a few recent randomized controlled trials suggest that antibiotic prophylaxis offers no advantage over intermittent antibiotic therapy of UTIs in terms of prevention of recurrent UTIs or new renal damage.