Management of the congenital solitary kidney: consensus recommendations of the Italian Society of Pediatric Nephrology.

BACKGROUND: In recent years, several studies have been published on the prognosis of children with congenital solitary kidney (CSK), with controversial results, and a worldwide consensus on management and follow-up is lacking. In this consensus statement, the Italian Society of Pediatric Nephrology summarizes the current knowledge on CSK and presents recommendations for its management, including diagnostic approach, nutritional and lifestyle habits, and follow-up. We recommend that any antenatal suspicion/diagnosis of CSK be confirmed by neonatal ultrasound (US), avoiding the routine use of further imaging if no other anomalies of kidney/urinary tract are detected. A CSK without additional abnormalities is expected to undergo compensatory enlargement, which should be assessed by US. We recommend that urinalysis, but not blood tests or genetic analysis, be routinely performed at diagnosis in infants and children showing compensatory enlargement of the CSK. Extrarenal malformations should be searched for, particularly genital tract malformations in females. An excessive protein and salt intake should be avoided, while sport participation should not be restricted. We recommend a lifelong follow-up, which should be tailored on risk stratification, as follows: low risk: CSK with compensatory enlargement, medium risk: CSK without compensatory enlargement and/or additional CAKUT, and high risk: decreased GFR and/or proteinuria, and/or hypertension. We recommend that in children at low-risk periodic US, urinalysis and BP measurement be performed; in those at medium risk, we recommend that serum creatinine also be measured; in high-risk children, the schedule has to be tailored according to kidney function and clinical data.

Born with a solitary kidney: at risk of hypertension.

BACKGROUND: Subjects with a congenital solitary kidney (CSK) are believed to be at risk of hypertension due to their low number of nephrons. However, as CSK is a congenital abnormality of the kidney or urinary tract (CAKUT), subtle dysplastic changes contributing to hypertension cannot be excluded. METHODS: We retrospectively compared office blood pressure (OBP) and ambulatory blood pressure monitoring (ABPM) between two groups of children with CAKUT, aged 6-18 years: Group A with a CSK and Group B with two kidneys. All had normal renal parenchyma on scintigraphy and normal renal function. OBP and mean systolic and diastolic 24-h, daytime and nighttime ambulatory BP records were analyzed. The distribution of OBP and APBM as continuous values and the prevalence of hypertension (ambulatory/severe ambulatory or masked hypertension) in the two groups were compared. RESULTS: There were 81 patients in Group A and 45 in Group B. Median OBP standard deviation scores were normal in both groups, without significant differences. Median ABPM standard deviation scores, although normal, were significantly higher in Group A and the prevalence of hypertension was higher (ambulatory/severe ambulatory or masked) (33.3 vs. 13.3%, p = 0.019), mainly because of the greater occurrence of masked hypertension. CONCLUSIONS: Our data show that a CSK per se can be associated with an increased risk of hypertension from the pediatric age. Therefore, ABPM, which has proved valuable in the screening of hypertension, is warranted in children with a CSK, even if laboratory and imaging assessment is otherwise normal.

Updated Italian recommendations for the diagnosis, treatment and follow-up of the first febrile urinary tract infection in young children.

AIM: Our aim was to update the recommendations for the diagnosis, treatment and follow-up of the first febrile urinary tract infection in young children, which were endorsed in 2012 by the Italian Society of Pediatric Nephrology. METHODS: The Italian recommendations were revised on the basis of a review of the literature published from 2012 to October 2018. We also carried out an ad hoc evaluation of the risk factors to identify children with high-grade vesicoureteral reflux or renal scarring, which were published in the previous recommendations. When evidence was not available, the working group held extensive discussions, during various meetings and through email exchanges. RESULTS: Four major modifications have been introduced. The method for collecting urine for culture and its interpretation has been re-evaluated. We have reformulated the algorithm that guides clinical decisions to proceed with voiding cystourethrography. The suggested antibiotics have been revised, and we have recommended further restrictions of the use of antibiotic prophylaxis. CONCLUSION: These updated recommendations have now been endorsed by the Italian Society of Pediatric Nephrology and the Italian Society for Pediatric Infectivology. They can also be used to compare other recommendations that are available, as a worldwide consensus in this area is still lacking.

Congenital Solitary Kidney in Children: Size Matters.

PURPOSE: We assessed renal function outcome in children with congenital solitary kidney and evaluated prognostic risk factors. MATERIALS AND METHODS: We retrospectively studied the clinical charts of 210 children presenting with congenital solitary kidney at 2 pediatric nephrology and 5 pediatric units between January 2009 and October 2012. Children 0 to 18 years old with a congenital solitary kidney confirmed by scintigraphy were enrolled. Of the patients 146 were suitable for analysis. Median followup was 4.6 years. Primary outcome was decreased estimated glomerular filtration rate, and secondary outcome was occurrence of proteinuria and/or systemic hypertension. Primary outcome-free survival analysis was performed, including multiple regression analysis of significant risk factors. RESULTS: Decreased estimated glomerular filtration rate was present in 12% of children at a median age of 2.2 years. Primary outcome-free survival analysis revealed an estimated event-free survival of 82% (95% CI 74% to 91%) at 10 years. Estimated survival rate was significantly decreased in children with additional congenital anomalies of the kidney/urinary tract (54% vs 88% overall) or insufficient renal length vs expected for normal congenital solitary kidney. The latter was the strongest predictor of decreased estimated outcome-free survival (49% vs 89%, p <0.001). Occurrence of proteinuria and/or systemic hypertension was present in less than 5% of children. CONCLUSIONS: Some children with congenital solitary kidney show decreased glomerular filtration rate. Associated anomalies of the kidney/urinary tract and insufficient renal length appear to be significant risk factors. Adequate length of the congenital solitary kidney is a key parameter for maintenance of renal function and should be examined routinely during followup.

Copy-number disorders are a common cause of congenital kidney malformations.

We examined the burden of large, rare, copy-number variants (CNVs) in 192 individuals with renal hypodysplasia (RHD) and replicated findings in 330 RHD cases from two independent cohorts. CNV distribution was significantly skewed toward larger gene-disrupting events in RHD cases compared to 4,733 ethnicity-matched controls (p = 4.8 × 10(-11)). This excess was attributable to known and novel (i.e., not present in any database or in the literature) genomic disorders. All together, 55/522 (10.5%) RHD cases harbored 34 distinct known genomic disorders, which were detected in only 0.2% of 13,839 population controls (p = 1.2 × 10(-58)). Another 32 (6.1%) RHD cases harbored large gene-disrupting CNVs that were absent from or extremely rare in the 13,839 population controls, identifying 38 potential novel or rare genomic disorders for this trait. Deletions at the HNF1B locus and the DiGeorge/velocardiofacial locus were most frequent. However, the majority of disorders were detected in a single individual. Genomic disorders were detected in 22.5% of individuals with multiple malformations and 14.5% of individuals with isolated urinary-tract defects; 14 individuals harbored two or more diagnostic or rare CNVs. Strikingly, the majority of the known CNV disorders detected in the RHD cohort have previous associations with developmental delay or neuropsychiatric diseases. Up to 16.6% of individuals with kidney malformations had a molecular diagnosis attributable to a copy-number disorder, suggesting kidney malformations as a sentinel manifestation of pathogenic genomic imbalances. A search for pathogenic CNVs should be considered in this population for the diagnosis of their specific genomic disorders and for the evaluation of the potential for developmental delay.

Best practice guidelines for idiopathic nephrotic syndrome: recommendations versus reality.

BACKGROUND: The optimal therapeutic regimen for managing childhood idiopathic nephrotic syndrome (INS) is still under debate. We have evaluated the choice of steroid regimen and of symptomatic treatment adopted by pediatricians and pediatric nephrologists in a large number of centers as the first step towards establishing a shared protocol METHODS: This was a multicenter, retrospective study. A total of 231 children (132 admitted to pediatric units) aged 6 months to <15 years who presented with onset of nephrotic syndrome to 54 pediatric units and six pediatric nephrology units in Italy between 2007 and 2009 were eligible for entry into the study. RESULTS: Median steroid dosing was 55 (range 27-75) mg/m(2)/day. The overall median cumulative dose regimen for the first episode was 3,440 (1,904-6,035) mg/m(2), and the median duration of the therapeutic regimen was 21 (9-48) weeks. The total duration and cumulative steroid dose were significantly higher in patients treated by pediatricians than in those treated by pediatric nephrologists (p = 0.001 and p = 0.008). Among the patient cohort, 55, 64 and 22 % received albumin infusions, diuretics and acetyl salicylic acid treatment, respectively, but the laboratory and clinical data did not differ between children treated or not treated with symptomatic drugs. Albumin and diuretic use did not vary between patients in pediatric units and those in pediatric nephrology units. CONCLUSIONS: This study shows major differences in steroid and symptomatic treatment of nephrotic syndrome by pediatricians and pediatric nephrologists. As these differences can influence the efficacy of the treatments and the appearance of side-effects, shared guidelines and their implementation through widespread educational activities are necessary.

Long-term clinical consequences of urinary tract infections during childhood: a review.

UNLABELLED: Kidney scarring related to urinary tract infection in childhood has been considered the cause of serious long-term clinical consequences. This assumption is now debated, as the advent of routine antenatal ultrasound in the 1980s has shown that a consistent part of the changes previously attributed to postinfectious scarring is mainly due to congenital malformations. With the aim of determining what is presently known on the long-term clinical consequences of urinary tract infections (UTIs) in childhood, we performed a review of the literature on the relation between UTIs and blood pressure, renal function, growth and pregnancy-related complications. By searching Medline/PubMed and Embase from 1980 to 2011, we identified 20 cohorts of children from 23 papers. CONCLUSIONS: Renal function: there are no clear data to establish long-term consequences following UTIs during childhood. Most data seem to show that the outcome of renal function can already be delineated at first presentation or in the initial years of follow-up; only 0.4% of children with normal renal function at start presented a decrease during follow-up. Hypertension: there is a low risk, associated with renal damage. Growth and pregnancy-related complications: the few available data seem to exclude a major influence of UTIs.

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

UNLABELLED: 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.

Nephrocalcinosis in children: a retrospective multi-centre study.

AIM: To review the data of children with NC and to analyse aetiology, clinical manifestations, growth and renal function at presentation; to relate growth and renal function to changes in NC in patients with a follow-up of at least 12 months. METHODS: Data of 41 children from four institutions were gathered retrospectively. RESULTS: Presenting symptoms were failure to thrive in the first year of life (41%), urinary tract infections, bladder voiding dysfunction or abdominal pain (17%) and psychomotor delay (10%). In 24% of cases NC was detected incidentally. Glomerular function at diagnosis was normal in 83% of children. During a median follow-up of 4 yrs and 5 months in 28 patients, growth standard deviation score improved from a median of -2.2 to -1.0 and glomerular function remained stable in 89% of patients, in spite of worsening of the degree of NC in 62% of cases. The most frequent causes of NC were hereditary tubulopathies and vitamin D intoxication. CONCLUSION: Our results show that the treatment of the underlying conditions is associated with catch-up growth and stabilization of glomerular function in many children, but not with the reduction in the degree of NC in the majority of cases. We believe that early recognition of conditions leading to NC is clinically useful and suggest a diagnostic flowchart, which may be helpful in the approach to NC.

Prescription of drugs blocking the renin-angiotensin system in Italian children.

Little is known about the prescription pattern of antihypertensive drugs for children with impaired kidney function. We have therefore documented the use of antihypertensive drugs in this patient group by evaluating the Italian pediatric population-based registry of patients with chronic kidney disease on conservative treatment (ItalKid) from 1995 to 2003. In 1995, prescriptions written for antihypertensive drugs for use by children were approximately equally divided among drugs blocking the renin-angiotensin system and calcium channel blockers (38 vs. 43% of all prescriptions), followed by beta-blockers and diuretics (15 and 4%, respectively). During subsequent years the proportion of prescriptions for drugs blocking the renin-angiotensin system increased (2003: 61%; p<0.001) and that of calcium channel blockers decreased (2003: 18%, p<0.001). In 1995, blockers of the renin-angiotensin system were prescribed, either as monotherapy or in combination, in 53% of the patients, but the relative frequency of the patients prescribed these drugs increased up to 83% in 2003 (p<0.0005). In conclusion, physicians caring for Italian children with impaired kidney function are increasingly prescribing drugs blocking the renin-angiotensin system.

No clear evidence of ACEi efficacy on the progression of chronic kidney disease in children with hypodysplastic nephropathy--report from the ItalKid Project database.

BACKGROUND: Chronic kidney diseases (CKD) tend to progress to end-stage renal failure (ESRF). As it has been demonstrated that angiotensin-converting enzyme inhibitors (ACEi) have a renoprotective effect in adults with proteinuric disease and may be effective in reducing hyperfiltration and proteinuria, they are also frequently used as anti-progression agents in paediatric patients with CKD despite the lack of data confirming their role in the nephropathies peculiar to children. The aim of this study was to investigate whether patients with hypodysplastic CKD (the most common cause of ESRF in children) treated with ACEi show a significantly slower decline in creatinine clearance (Ccr). METHODS: The analysis was based on the information available in the database of the ItalKid Project, a nationwide, population-based registry of chronic renal insufficiency (CRI) in children in Italy. Of the 822 patients with CRI due to hypodysplasia, we selected those who had been continuously treated with ACEi; the control patients were identified from the same diagnostic group and matched for gender, age and baseline Ccr. RESULTS: Progression was analysed as the slope of Ccr in a total of 164 patients: 41 cases and 123 matched controls. There were no significant between-group differences in blood pressure, duration of follow-up or pre-study slope of Ccr (-0.31+/-2.26 vs -0.33+/-3.58 ml/min/1.73 m2/year; P=NS). After an average of 4.9+/-2.3 years, the mean slope of Ccr was 40% lower in the ACEi-treated cases in comparison to controls (-1.08+/-2.08 vs -1.80+/-4.42 ml/min/1.73 m2/year), however, this difference was not statistically significant (P=0.31). CONCLUSIONS: We conclude that ACEi treatment does not significantly modify the naturally progressive course of hypodysplastic nephropathy in children and further studies are necessary before such treatment is routinely proposed for anti-progression purposes in children with CKD.

Idiopathic hypercalciuria in infants with renal stones.

In children older than 2 years, hypercalciuria is the most common metabolic cause of renal stones. In infants, its prevalence is not well established. Since 1990, we observed five infants in whom renal stones or microcalculi were diagnosed between the age of 5 and 19 months. One of them was lost to follow up. In the present report, we describe the four patients who underwent metabolic evaluation and in whom idiopathic hypercalciuria (IH) was diagnosed. We conclude that IH is a frequent cause of microcalculi and renal stones in infants, and a screen for this condition is warranted in this age group.

Phenotypic and genetic heterogeneity in Dent's disease--the results of an Italian collaborative study.

BACKGROUND: Dent's disease is an inherited tubulopathy caused by CLCN5 gene mutations. While a typical phenotype characterized by low-molecular-weight (LMW) proteinuria, hypercalciuria, nephrocalcinosis, nephrolithiasis, rickets and progressive renal failure in various combinations often enables a clinical diagnosis, less severe sub-clinical cases may go under-diagnosed. METHODS: By single-strand conformation polymorphism analysis and direct sequencing, we screened 40 male patients from 40 unrelated families for CLCN5 gene mutations. Twenty-four of these patients had the prominent features of Dent's disease, including LMW proteinuria, hypercalciuria and nephrocalcinosis. RESULTS: We identified 24 mutations in the CLCN5 gene in 21/24 patients with a typical phenotype and in 3/16 patients with a partial clinical picture of Dent's disease. Overall, 10 novel CLCN5 mutations were identified (E6fsX11, W58fsX97, 267 del E, Y272C, N340K, F444fsX448, W547X, Q600X, IVS3 +2 G>C and IVS3 -1 G>A), extending the number of mutations identified so far from 75 to 85. The CLCN5 coding sequence was normal in three patients. In the group with an incomplete Dent's disease phenotype, we detected two intronic mutations and one silent substitution leading to the up regulation of an alternatively spliced isoform. CONCLUSIONS: Our data confirm the genetic heterogeneity of Dent's disease. In most classic cases, the clinical diagnosis is confirmed by genetic tests.

Middle molecule and small protein removal in children on peritoneal dialysis.

BACKGROUND: Dialysis efficiency has a great influence on the outcome of patients. Few data are available on the removal of solutes with molecular weights higher than urea and creatinine. The aim of our study was to assess the transport and the removal of substances with molecular weights up to 15 kD and to evaluate the contribution of residual renal function in peritoneal dialysis (PD) children. METHODS: Seventeen patients of 12 +/- 4 years undergoing automated PD were studied. Ten patients had 563 +/- 355 mL/day of urine output, and 7 were anuric. During a standardized nightly intermittent PD (NIPD) session, a single-injection inulin clearance was performed. Urea, creatinine, inulin (measured by HPLC), cystatin C and beta2-microglobulin (beta2m) were measured in blood, urine and dialysate. Clearances (L/week/1.73 m2) and weekly solute removal index (SRI) were calculated for all the solutes; weekly Kt/V was calculated for urea. RESULTS: In non-anuric versus anuric patients the total clearances were: urea 82.6 +/- 18.3 versus 71.3 +/- 26.4; creatinine 82.7 +/- 28.6 versus 47.8 +/- 18.8; inulin 42.8 +/- 11.3 versus 32.8 +/- 20.4; beta2m 14.2 +/- 13.8 versus 9.2 +/- 8.3; cystatin C 20.2 +/- 9.4 versus 9.7 +/- 4.8. In the patients with residual diuresis, the urea was removed mainly by PD (69.2%), while inulin, beta2m and cystatin C were removed by renal clearance (64.0%, 79.5% and 62.8%, respectively). Total, peritoneal and renal weekly Kt/V values in the subjects with residual renal function, were 2.86 +/- 0.70, 1.99 +/- 0.40 and 0.87 +/- 0.43, respectively. Peritoneal weekly Kt/V in the anuric patients was 2.36 +/- 0.85; total weekly Kt/V in the total group was 2.65 +/- 0.78. Weekly SRIs in non-anuric versus anuric patients were: urea 2.56 +/- 0.58 versus 2.09 +/- 0.74; creatinine 2.66 +/- 0.73 versus 1.46 +/- 0.56; inulin 2.36 +/- 0.92 versus 1.64 +/- 1.60; beta2m 1.26 +/- 1.10 versus 1.20 +/- 1.90; cystatin C 1.72 +/- 0.83 versus 1.58 +/- 1.62. CONCLUSIONS: Solutes removed during PD tend to decrease following an increase in molecular weight of the substance. Since anuric patients are at higher risk of middle molecule and small protein accumulation, more attention should be paid to the removal of middle molecules. Further studies should be undertaken to evaluate whether removing them has a clinical impact and to determine their threshold levels.