Histologic and Clinical Factors Associated with Kidney Outcomes in IgA Vasculitis Nephritis.

BACKGROUND: Nephritis is a common manifestation of IgA vasculitis and is morphologically indistinguishable from IgA nephropathy. While MEST-C scores are predictive of kidney outcomes in IgA nephropathy, their value in IgA vasculitis nephritis has not been investigated in large multiethnic cohorts. METHODS: Biopsies from 262 children and 99 adults with IgA vasculitis nephritis ( N =361) from 23 centers in North America, Europe, and Asia were independently scored by three pathologists. MEST-C scores were assessed for correlation with eGFR/proteinuria at biopsy. Because most patients ( N =309, 86%) received immunosuppression, risk factors for outcomes were evaluated in this group using latent class mixed models to identify classes of eGFR trajectories over a median follow-up of 2.7 years (interquartile range, 1.2-5.1). Clinical and histologic parameters associated with each class were determined using logistic regression. RESULTS: M, E, T, and C scores were correlated with either eGFR or proteinuria at biopsy. Two classes were identified by latent class mixed model, one with initial improvement in eGFR followed by a late decline (class 1, N =91) and another with stable eGFR (class 2, N =218). Class 1 was associated with a higher risk of an established kidney outcome (time to ≥30% decline in eGFR or kidney failure; hazard ratio, 5.84; 95% confidence interval, 2.37 to 14.4). Among MEST-C scores, only E1 was associated with class 1 by multivariable analysis. Other factors associated with class 1 were age 18 years and younger, male sex, lower eGFR at biopsy, and extrarenal noncutaneous disease. Fibrous crescents without active changes were associated with class 2. CONCLUSIONS: Kidney outcome in patients with biopsied IgA vasculitis nephritis treated with immunosuppression was determined by clinical risk factors and endocapillary hypercellularity (E1) and fibrous crescents, which are features that are not part of the International Study of Diseases of Children classification.

Prevalence and potential relevance of hyperuricemia in pediatric kidney transplant recipients-a CERTAIN registry analysis.

BACKGROUND: Asymptomatic hyperuricemia is frequently observed in pediatric kidney transplant recipients; symptomatic hyperuricemia, however, is a rare complication. Only few data are available in this patient population. We, therefore, investigated the prevalence of hyperuricemia and its association with kidney transplant function and blood pressure in a multicenter cohort of pediatric kidney transplant recipients. METHODS: This is a retrospective, observational multicenter registry study. All pediatric kidney transplant recipients in the CERTAIN database with at least one documented serum uric acid level and a follow-up of 5 years posttransplant were eligible. We identified 151 patients with 395 measurements of serum uric acid. We calculated the prevalence of hyperuricemia, analyzed potential risk factors and clinical consequences such as elevated blood pressure and reduced estimated glomerular filtration rate (eGFR). Statistical analysis was performed using IBM SPSS Statistics 26. RESULTS: One hundred and ten of 395 (27.8%) serum uric acid levels were above 416 µmol/L (7.0 mg/dL), defined as the upper limit of normal. Univariate analysis showed a significant (p = .026) inverse association of serum uric acid with eGFR overtime. There was no significant association of serum uric acid concentrations with body mass index (z-score), blood pressure (z-score), or sex. No episodes of gout were documented. CONCLUSION: This study shows that hyperuricemia is present in a considerable number of patients sometime after pediatric kidney transplantation and is associated with lower eGFR. Whether hyperuricemia contributes to faster decline of graft function or to the overall cardiovascular risk of these patients remains to be elucidated.

Influenza-associated hemolytic uremic syndrome: The pathogenic role of the virus.

A 3-year-old girl came to our attention for fever and upper respiratory tract infection associated with thrombocytopenia, non-immune hemolytic anemia, and acute kidney injury (AKI). Complete blood count and renal function slowly normalized, with no need for dialysis. She was always normotensive with valid diuresis; her neurological status also rapidly improved. Nasal swab turned out positive for influenza A H1N1; stool test was negative for Shiga toxin-producing Escherichia coli (STEC). The patient was treated with oseltamivir for 5 days with a favorable outcome. Association between hemolytic uremic syndrome (HUS) and H1N1 influenza is poorly reported in literature [1, 2, 3, 4]. The pathogenic role of the virus in causing HUS is still controversial and debated [1, 2, 3, 4]. In our patient, complement activity markers (serum C3 and C5b-9) alteration suggested a transient, virus-mediated complement activation.

Results of the PROPINE randomized controlled study suggest tapering of prednisone treatment for relapses of steroid sensitive nephrotic syndrome is not necessary in children.

Corticosteroid-related toxicity in children with steroid-sensitive nephrotic syndrome is primarily related to the cumulative dose of prednisone. To optimize treatment of relapses, we conducted the PROPINE study, a multicentric, open-label, randomized, superiority trial. Seventy-eight relapsing children aged 3-17 years who had not received steroid-sparing medications during the previous 12 months were randomized to receive, from day five after remission, either 18 doses of 40 mg/m2 of prednisone on alternate days (short arm), or the same cumulative dose tapered over double the time (long arm). Patients were monitored with an ad-hoc smartphone application, allowing daily reporting. The primary outcome was the six-month relapse rate at which time, 23/40 and 16/38 patients had relapsed in the long and short arms, respectively (no significant difference). Additionally, 40/78 patients were also enrolled in a secondary crossover study and were allocated to the opposite arm. Altogether, at six months, the relapse rate was 32/40 and 28/40 in the long and short arms, respectively (no significant difference). A post-hoc analysis excluding 30 patients treated with low-dose prednisone maintenance therapy failed to show significant differences between the two arms. No differences in adverse events, blood pressure and weight gain were observed. Thus, our data do not support the prescription of prolonged tapering schedules for relapses of steroid-sensitive nephrotic syndrome in children.

Summary of Expert Opinion on the Management of Children With Chronic Kidney Disease and Growth Failure With Human Growth Hormone.

Background: The management of children and adolescents with chronic kidney disease (CKD) and growth failure candidate for recombinant human growth hormone therapy (rhGH) is based on an appraisal of the literature established on a 2006 consensus statement and 2019 Clinical practice recommendations. The performance of these guidelines has never been tested. Aims: The objective of this study was to establish the level of adherence to international guidelines based on the 2006 consensus and the 2019 criteria that lead to the initiation of growth hormone treatment by both pediatric endocrinologists and pediatric nephrologists. Methods: A multidisciplinary team of pediatric endocrinologists and pediatric nephrologists, members of the Italian Society of Pediatric Endocrinology or of the Italian Society of Pediatric Nephrology, discussed and reviewed the main issues related to the management of pediatric patients with CKD who need treatment with rhGH. Experts developed 11 questions focusing on risk assessment and decision makings in October 2019 and a survey was sent to forty pediatric endocrinologists (n = 20) and nephrologists (n = 20) covering the whole national territory. The results were then analyzed and discussed in light of current clinical practice guidelines and recent recommendations. Results: Responses were received from 32 of the 40 invited specialists, 17 of whom were pediatric endocrinologists (42.5%) and 15 pediatric nephrologists (37.5%). Although all the centers that participated in the survey agreed to follow the clinical and biochemical diagnostic work-up and the criteria for the treatment of patients with CKD, among the Italian centers there was a wide variety of decision-making processes. Conclusions: Despite current guidelines for the management of children with CKD and growth failure, its use varies widely between centers and rhGH is prescribed in a relatively small number of patients and rarely after kidney transplantation. Several raised issues are not taken into account by international guidelines and a multidisciplinary approach with mutual collaboration between specialists will improve patient care based on their unmet needs.

Continuous kidney replacement therapy in critically ill neonates and infants: a retrospective analysis of clinical results with a dedicated device.

BACKGROUND: Providing extracorporeal renal support to neonates and infants involves a number of technical and clinical issues, possibly discouraging early utilization. This report aims to describe a multicenter experience of continuous kidney replacement therapy (CKRT) delivery to small infants using a device specifically designed for this age group. METHODS: A retrospective cohort analysis of all patients treated with the Carpediem™ machine (Bellco-Medtronic, Mirandola, Italy) in 6 centers between June 2013 and December 2016. RESULTS: Twenty-six neonates and small infants received 165 CKRT sessions in convective modality. Median age at neonatal intensive care unit admission 1 day (IQR 1-11), median body weight 2.9 kg (IQR 2.2-3.6). Median circuit duration 14 h (IQR 10-22), with delivered/prescribed time ratio of 84%. CKRT was conducted using 4 Fr (27%), 5 Fr (35%), 6.5 Fr (11%), and 7 Fr (3%) vascular access, and with umbilical and peripheral accesses (11% each) allowing overall median blood flow of 4.5 ml/kg/min (IQR 3.4-6) and median effluent flow rate 35 ml/kg/h (IQR 28-42). Circuits were primed with normal saline in 58% of treatments, colloids in 31%, and packed red blood cells in 11%. No serious adverse events directly related to machine application were reported by any center. Twenty-five (96%) patients survived their CKRT course and 13 patients (50%) survived to ICU discharge. CONCLUSIONS: CKRT in neonates was easy to initiate and conduct when performed with small central vascular accesses coupled with this device. A dedicated technology for infant CKRT delivery enables patients to be safely treated avoiding technical complications. Graphical abstract.

Genetic Analyses in Dent Disease and Characterization of CLCN5 Mutations in Kidney Biopsies.

Dent disease (DD), an X-linked renal tubulopathy, is mainly caused by loss-of-function mutations in CLCN5 (DD1) and OCRL genes. CLCN5 encodes the ClC-5 antiporter that in proximal tubules (PT) participates in the receptor-mediated endocytosis of low molecular weight proteins. Few studies have analyzed the PT expression of ClC-5 and of megalin and cubilin receptors in DD1 kidney biopsies. About 25% of DD cases lack mutations in either CLCN5 or OCRL genes (DD3), and no other disease genes have been discovered so far. Sanger sequencing was used for CLCN5 gene analysis in 158 unrelated males clinically suspected of having DD. The tubular expression of ClC-5, megalin, and cubilin was assessed by immunolabeling in 10 DD1 kidney biopsies. Whole exome sequencing (WES) was performed in eight DD3 patients. Twenty-three novel CLCN5 mutations were identified. ClC-5, megalin, and cubilin were significantly lower in DD1 than in control biopsies. The tubular expression of ClC-5 when detected was irrespective of the type of mutation. In four DD3 patients, WES revealed 12 potentially pathogenic variants in three novel genes (SLC17A1, SLC9A3, and PDZK1), and in three genes known to be associated with monogenic forms of renal proximal tubulopathies (SLC3A, LRP2, and CUBN). The supposed third Dent disease-causing gene was not discovered.

Acute Kidney Injury in Critically Ill Children: A Retrospective Analysis of Risk Factors.

INTRODUCTION: Children admitted to paediatric intensive care unit (PICU) are at risk of acute kidney injury (AKI). However, few paediatric studies have focused on the identification of factors potentially associated with the development of this condition. The aim of our study was to assess the incidence rate of AKI, identify risk factors, and evaluate clinical outcome in a large sample of critically ill children. METHODS: This retrospective observational study was conducted including patients admitted to our PICU from January 2014 to December 2016. AKI was defined according to Kidney Disease: Improving Global Outcome criteria. RESULTS: A total of 222 PICU patients out of 811 (27%) had AKI (stage I 39%, stage II 24%, stage III 37%). The most common PICU admission diagnoses in AKI cases were heart disease (38.6%), respiratory failure (16.8%) and postsurgical non-cardiac patients (11%). Hypoxic-ischaemic was the most frequent cause of AKI. Significant risk factors for AKI following multivariate analysis were age >2 months (OR 2.43; 95% CI 1.03-7.87; p = 0.05), serum creatinine at admission >44 µmol/L (OR 2.23; 95% CI 1.26-3.94; p = 0.006), presence of comorbidities (OR 1.84; 95% CI 1.03-3.30; p = 0.04), use of inotropes (OR 2.56; 95% CI 1.23-5.35; p= 0.012) and diuretics (OR 2.78; 95% CI 1.49-5.19; p = 0.001), exposure to nephrotoxic drugs (OR 1.66; 95% CI 1.01-2.91; p= 0.04), multiple organ dysfunction syndrome (OR 2.68; 95% CI 1.43-5.01; p = 0.002), and coagulopathy (OR 1.89; 95% CI 1.05-3.38, p = 0.03). AKI was associated with a significant longer PICU stay (median LOS of 8 days, interquartile range [IQR] 3-16, versus 4 days, IQR 2-8, in non-AKI patients; p < 0.001). The mortality rate resulted tenfold higher in AKI than non-AKI patients (12.6 vs. 1.2%; p < 0.001). CONCLUSIONS: The incidence of AKI in critically ill children is high, with an associated increased length of stay and risk of mortality. In the PICU setting, risk factors of AKI are multiple and mainly associated with illness severity.

Post-transplant recurrence of steroid resistant nephrotic syndrome in children: the Italian experience.

BACKGROUND: Steroid resistant nephrotic syndrome (SRNS) is a frequent cause of end stage renal disease in children and post-transplant disease recurrence is a major cause of graft loss. METHODS: We identified all children with SRNS who underwent renal transplantation in Italy, between 2005 and 2017. Data were retrospectively collected for the presence of a causative gene mutation, sex, histology, duration of pre-transplant dialysis, age at onset and transplant, HLA matching, recurrence, therapy for recurrence, and graft survival. RESULTS: 101 patients underwent a first and 22 a second renal transplant. After a median follow-up of 58.5 months, the disease recurred on the first renal transplant in 53.3% of patients with a non-genetic and none with a genetic SRNS. Age at transplant > 9 years and the presence of at least one HLA-AB match were independent risk factors for recurrence. Duration of dialysis was longer in children with relapse, but did not reach statistical significance. Overall, 24% of patients lost the first graft, with recurrence representing the commonest cause. Among 22 patients who underwent a second transplant, 5 suffered of SRNS recurrence. SRNS relapsed in 5/9 (55%) patients with disease recurrence in their first transplant and 2 of them lost the second graft. CONCLUSIONS: Absence of a causative mutation represents the major risk factor for post-transplant recurrence in children with SRNS, while transplant can be curative in genetic SRNS. A prolonged time spent on dialysis before transplantation has no protective effect on the risk of relapse and should not be encouraged. Retransplantation represents a second chance after graft loss for recurrence.

Sex and age as determinants for high blood pressure in pediatric renal transplant recipients: a longitudinal analysis of the CERTAIN Registry.

BACKGROUND: High prevalence of arterial hypertension is known in pediatric renal transplant patients, but how blood pressure (BP) distribution and control differ between age groups and whether sex and age interact and potentially impact BP after transplantation have not been investigated. METHODS: This retrospective analysis included 336 pediatric renal transplant recipients (62% males) from the Cooperative European Pediatric Renal Transplant Initiative Registry (CERTAIN) with complete BP measurement at discharge and 1, 2 and 3 years post-transplant. RESULTS: At discharge and 3 years post-transplant, arterial hypertension was highly prevalent (84% and 77%); antihypertensive drugs were used in 73% and 68% of the patients. 27% suffered from uncontrolled and 9% from untreated hypertension at 3 years post-transplant. Children transplanted at age < 5 years showed sustained high systolic BP z-score and received consistently less antihypertensive treatment over time. Younger age, shorter time since transplantation, male sex, higher body mass index (BMI), high cyclosporine A (CSA) trough levels, and a primary renal disease other than congenital anomalies of the kidney and urinary tract (CAKUT) were significantly associated with higher systolic BP z-score. Sex-stratified analysis revealed a significant association between high CSA and higher systolic BP in older girls that likely had started puberty already. An association between BP and estimated glomerular filtration rate was not detected. CONCLUSIONS: BP control during the first 3 years was poor in this large European cohort. The description of age- and sex-specific risk profiles identified certain recipient groups that may benefit from more frequent BP monitoring (i.e. young children) or different choices of immunosuppression (i.e. older girls).

Reverse Phenotyping after Whole-Exome Sequencing in Steroid-Resistant Nephrotic Syndrome.

BACKGROUND AND OBJECTIVES: Nephrotic syndrome is a typical presentation of genetic podocytopathies but occasionally other genetic nephropathies can present as clinically indistinguishable phenocopies. We hypothesized that extended genetic testing followed by reverse phenotyping would increase the diagnostic rate for these patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: All patients diagnosed with nephrotic syndrome and referred to our center between 2000 and 2018 were assessed in this retrospective study. When indicated, whole-exome sequencing and in silico filtering of 298 genes related to CKD were combined with subsequent reverse phenotyping in patients and families. Pathogenic variants were defined according to current guidelines of the American College of Medical Genetics. RESULTS: A total of 111 patients (64 steroid-resistant and 47 steroid-sensitive) were included in the study. Not a single pathogenic variant was detected in the steroid-sensitive group. Overall, 30% (19 out of 64) of steroid-resistant patients had pathogenic variants in podocytopathy genes, whereas a substantial number of variants were identified in other genes, not commonly associated with isolated nephrotic syndrome. Reverse phenotyping, on the basis of a personalized diagnostic workflow, permitted to identify previously unrecognized clinical signs of an unexpected underlying genetic nephropathy in a further 28% (18 out of 64) of patients. These patients showed similar multidrug resistance, but different long-term outcome, when compared with genetic podocytopathies. CONCLUSIONS: Reverse phenotyping increased the diagnostic accuracy in patients referred with the diagnosis of steroid-resistant nephrotic syndrome.

Acute dialysis in children: results of a European survey.

The number of children with acute kidney injury (AKI) requiring dialysis is increasing. To date, systematic analysis has been largely limited to critically ill children treated with continuous renal replacement therapy (CRRT). We conducted a survey among 35 European Pediatric Nephrology Centers to investigate dialysis practices in European children with AKI. Altogether, the centers perform dialysis in more than 900 pediatric patients with AKI per year. PD and CRRT are the most frequently used dialysis modalities, accounting for 39.4% and 38.2% of treatments, followed by intermittent HD (22.4%). In units treating more than 25 cases per year and in those with cardiothoracic surgery programs, PD is the most commonly chosen dialysis modality. Also, nearly one quarter of centers, in countries with a gross domestic product below $35,000/year, do not utilize CRRT at all. Dialysis nurses are exclusively in charge of CRRT management in 45% of the cases and pediatric intensive care nurses in 25%, while shared management is practiced in 30%. In conclusion, this survey indicates that the choice of treatment modalities for dialysis in children with AKI in Europe is affected by the underlying ethiology of the disease, organization/set-up of centers and socioeconomic conditions. PD is utilized as often as CRRT, and also intermittent HD is a commonly applied treatment option. A prospective European AKI registry is planned to provide further insights on the epidemiology, management and outcomes of dialysis in pediatric AKI.

An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome.

RATIONALE & OBJECTIVE: Although primary atypical hemolytic uremic syndrome (aHUS) is associated with abnormalities in complement genes and antibodies to complement factor H, the role of complement in secondary aHUS remains debatable. We evaluated the usefulness of an ex vivo test to: (1) detect complement activation within the endothelium in primary and secondary aHUS, (2) differentiate active disease from remission, (3) monitor the effectiveness of eculizumab therapy, and (4) identify relapses during eculizumab dosage tapering and after discontinuation of treatment. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: 121 patients with primary aHUS and 28 with secondary aHUS. Serum samples were collected during acute episodes, following remission, and during eculizumab treatment and were assessed using a serum-induced ex vivo C5b-9 endothelial deposition test. RESULTS: Serum-induced C5b-9 deposition on cultured microvascular endothelium was quantified by calculating the endothelial area covered by C5b-9 staining; values were expressed as percentage of C5b-9 deposits induced by a serum pool from healthy controls. Testing with adenosine diphosphate-activated endothelium demonstrated elevated C5b-9 deposits for all untreated patients with aHUS independent of disease activity, while testing with unstimulated endothelium demonstrated deposits only in active disease. Similar findings were observed in secondary aHUS. Serum-induced C5b-9 deposits on activated and unstimulated endothelium normalized during eculizumab treatment. 96% (22/23) of patients receiving eculizumab at extended 3- or 4-week dosing intervals demonstrated normal C5b-9 deposits on activated endothelium, despite most patients having CH50Eq (serum complement activity) > 20 UEq/mL, indicating that adequate complement control was achieved even with incomplete blockade of circulating C5. During eculizumab dosage tapering or after treatment discontinuation, all patients experiencing relapses versus only 6% (1/17) of those in stable remission had elevated C5b-9 deposits on unstimulated endothelium. LIMITATIONS: The C5b-9 endothelial deposition test can be performed in only specialized laboratories. Findings on eculizumab dosage tapering need to be confirmed with longitudinal monitoring of C5b-9 deposition. CONCLUSIONS: The C5b-9 endothelial deposition assay may represent an advance in our ability to monitor aHUS activity and individualize therapy.

Treatment and long-term outcome in primary distal renal tubular acidosis.

BACKGROUND: Primary distal renal tubular acidosis (dRTA) is a rare disorder, and we aimed to gather data on treatment and long-term outcome. METHODS: We contacted paediatric and adult nephrologists through European professional organizations. Responding clinicians entered demographic, biochemical, genetic and clinical data in an online form. RESULTS: Adequate data were collected on 340 patients (29 countries, female 52%). Mutation testing had been performed on 206 patients (61%); pathogenic mutations were identified in 170 patients (83%). The median (range) presentation age was 0.5 (0-54) years and age at last follow-up was 11.0 (0-70.0) years. Adult height was slightly below average with a mean (SD score) of -0.57 (±1.16). There was an increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (35%) and adults (82%). Nephrocalcinosis was reported in 88%. Nephrolithiasis was more common with SLC4A1 mutations (42% versus 21%). Thirty-six percent had hearing loss, particularly in ATP6V1B1 (88%). The median (interquartile range) prescribed dose of alkali (mEq/kg/day) was 1.9 (1.2-3.3). Adequate metabolic control (normal plasma bicarbonate and normocalciuria) was achieved in 158 patients (51%), more commonly in countries with higher gross domestic product (67% versus 23%), and was associated with higher height and estimated glomerular filtration rate. CONCLUSION: Long-term follow-up from this large dRTA cohort shows an overall favourable outcome with normal adult height for most and no patient with CKD Stage 5. However, 82% of adult patients have CKD Stages 2-4. Importance of adequate metabolic control was highlighted by better growth and renal function but was achieved in only half of patients.

Haemodiafiltration use in children: data from the Italian Pediatric Dialysis Registry.

BACKGROUND: High volume haemodiafiltration (HDF) is associated with better survival than conventional haemodialysis (HD) in adults, but data concerning its use in children are lacking. The aim of this study was to assess the prevalence of paediatric HDF use and its associated factors in recent years in Italy. METHODS: We retrospectively reviewed the files of patients from the Italian Pediatric Dialysis Registry's database who were registered between January 1, 2004 and December 31, 2016 and treated with extracorporeal dialysis for at least 6 months, looking in particular at modality and its associated factors. RESULTS: One hundred forty-one out of 198 patients were treated exclusively with bicarbonate HD (71.2%), 57 with HDF (28.8%). Patients treated with HDF were younger (median 9.7 vs 13.2 years, p = 0.0008), were less often incident patients (52.6% vs 75.9%, p = 0.0031), had longer duration of the HD cycle (26.9 vs 20.8 months, p = 0.0036) and had a longer time to renal transplantation (32 vs 25 months, p = 0.0029) than those treated with bicarbonate HD only. The percentage of patients treated with HDF increased with dialysis vintage (16.9% at 6 months, 38.1% after more than 2 years of dialysis). The use of HDF was stable over time and was more common in the largest centres. CONCLUSIONS: Over the observation period, HDF use in Italy has been limited to roughly a quarter of patients on extracorporeal dialysis, in particular to those with high dialysis vintage, younger age or a long expected waiting time to renal transplantation.

Epidemiology of and Risk Factors for BK Polyomavirus Replication and Nephropathy in Pediatric Renal Transplant Recipients: An International CERTAIN Registry Study.

BACKGROUND: BK polyomavirus-associated nephropathy (BKPyVAN) constitutes a serious cause of kidney allograft failure, but large-scale data in pediatric renal transplant recipients and a comprehensive analysis of specific risk factors are lacking. METHODS: We analyzed the data of 313 patients in the Cooperative European Pediatric Renal Transplant Initiative Registry, with an observation period of 3.3 years (range, 1-5). The net state of immunosuppressive therapy was assessed by the modified Vasudev score. RESULTS: Presumptive BKPyVAN (defined as sustained [>3 wk] high-level BK viremia >10 copies/mL) within 5 years posttransplant occurred in 49 (15.8%) of 311 patients, and biopsy-proven BKPyVAN in 14 (4.5%) of 313. BKPyV viremia was observed in 115 (36.7%) of 311 patients, of whom 11 (9.6%) of 115 developed viremia late, that is, after the second year posttransplant. In 6 (12.5%) of 48 patients with high-level viremia and in 3 (21.4%) of 14 with BKPyVAN, this respective event occurred late. According to multivariable analysis, BKPyV viremia and/or BKPyVAN were associated not only with a higher net state of immunosuppression (odds ratio [OR], 1.3; P < 0.01) and with tacrolimus-based versus ciclosporin-based immunosuppression (OR, 3.6; P < 0.01) but also with younger recipient age (OR, 1.1 per y younger; P < 0.001) and obstructive uropathy (OR, 12.4; P < 0.01) as primary renal disease. CONCLUSIONS: Uncontrolled BKPyV replication affects a significant proportion of pediatric renal transplant recipients and is associated with unique features of epidemiology and risk factors, such as young recipient age, obstructive uropathy, and overall intensity of immunosuppressive therapy. BKPyV surveillance should be considered beyond 2 years posttransplant in pediatric patients at higher risk.

Continuous Veno-Venous Hemodialysis Using the Cardio-Renal Pediatric Dialysis Emergency MachineTM: First Clinical Experiences.

We report the first worldwide experience with continuous veno-venous hemodialysis (CVVHD) in children using the last generation Cardio-Renal Pediatric Dialysis Emergency Machine (CARPEDIEM)TM device. Thirteen children received 1,008 h of CVVHD during 95 sessions, using a 0.15 (n = 7) or a 0.25 m2 (n = 6) hemofilter. The median weight was 3 kg (interquartile range [IQR] 2.5-6.2). In 10 patients, CVVHD was conducted using a 5 Fr double-lumen central vascular access, whereas in 3 children, bigger sizes were used (6.5 and 8 Ch). The median prescribed Qb was 17 mL/min (IQR 10-29.5), with a median Qd of 10 mL/min. Circuits were primed with 5% albumin in 12 out of 13 patients, using anticoagulation with heparin in all 13 cases. The median delivered/prescribed time ratio yielded a 100% result (95-100%). The most common cause for "downtime" was clotting that however occurred in only 3% of all treatments. Survivals at continuous renal replacement therapy discontinuation and ICU discharge were 100 and 69% respectively. The CARPEDIEMTM machine allowed successful delivery of diffusive blood purification modality to very small patients, using small catheters, no blood primes, and excellent concordance between delivered and prescribed treatment duration.

Choice of Catheter Size for Infants in Continuous Renal Replacement Therapy: Bigger Is Not Always Better.

OBJECTIVES: Renal replacement therapy in infants and small children is the treatment of choice for severe oligoanuric renal dysfunction, with an increasing consensus that early initiation might contribute to preventing acute kidney injury complications. Safer renal replacement therapy devices specifically designed for neonates may contribute to ameliorating outcomes and increasing chances of survival. One of the crucial factors to achieve an effective renal replacement therapy in small infants is adequate vascular access. The interaction of small size central vascular catheters with renal replacement therapy devices has never been investigated. The aim of this study was to characterize both the operating conditions and performance of three different central vascular catheters sizes (4F, 5F, and 7F) connected to two different extracorporeal blood circulation models (adult and pediatric). The rheologic performance of each vascular access size in combination with the adult and pediatric renal replacement therapy models was described. DESIGN: Series of experimental extracorporeal circulation circuit tests were conducted with different setups. A two-roller pump was used to simulate a standard adult dialysis machine, whereas a small three-roller pump served as pediatric renal replacement therapy device. SETTING: A pressure-flow setup aimed to collect pressure and flow values under different test conditions. A second experiment focused on hemolysis estimation induced by the extracorporeal system. Hemolysis exclusively induced by the 4F catheter was also evaluated. Finally, our data were applied to estimate the optimal catheter size theoretically capable of delivering adequate doses basing on anthropometric data (patient weight and cannulation site) in absence of direct ultrasound vessel measurement. SUBJECTS: In vitro tests conducted on simulated extracorporeal circuit models of continuous pediatric and neonatal renal replacement therapy. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: When 4F and 5F catheters are used, maximal blood flows within safe circuit pressures can be set at the values of 13 and 29 mL/min, respectively, when a small pump is used. Differently, when using adult roller pumps, only maximal flows of 10 and 20 mL/min are reached. However, hemolysis is higher when using a three-roller pump compared with the two-roller. The clinical impact of this increased hemolytic burden is likely not relevant. CONCLUSIONS: Small size central vascular catheters display optimal rheologic performances in terms of pressures and flows particularly when the renal replacement therapy device is equipped with pumps proportional to central vascular catheters sizes, and even when relatively high blood flows are set. This is achieved at the risk of a higher hemolysis rate.

Could the interaction between LMX1B and PAX2 influence the severity of renal symptoms?

Nail Patella syndrome (NPS) is a rare autosomal dominant disease characterized by varying degrees of patella, nail, and elbows dysplasia and also ocular and renal congenital abnormalities. The renal involvement, ranging from hematuria and proteinuria to end-stage renal disease, is present in 22-60% of NPS cases. Heterozygous variants in LMX1B are known to be responsible of NPS and it has been hypothesized that the variable expressivity is due to the interaction of LMX1B with other developmental genes. We reported a case of co-presence of LMX1B and PAX2 variants in a child with extrarenal manifestation of NPS and end-stage renal disease but congenital bilateral renal hypodysplasia and vesicoureteral reflux. The LMX1B variant was de novo, whereas the PAX2 variant was inherited from the mother that had bilateral renal hypoplasia although in presence of only a mild chronic kidney disease. The molecular interaction between LMX1B and PAX2 has been already reported in vitro and this finding suggest that the worst renal NPS phenotype of our patient could be due to the defective expression of these two genes during nephrogenesis. In conclusion, our finding suggests that PAX2 may act as modifier gene in Nail Patella phenotype.

Outcome of renal transplantation in small infants: a match-controlled analysis.

BACKGROUND: Infants with a body weight of less than 10 kg are often not considered to be suitable candidates for renal transplantation (RTx). The objective of this study was to evaluate this arbitrary weight threshold for pediatric RTx. METHODS: We conducted a multicenter, retrospective, match-controlled cohort study on infants weighing less than 10 kg at time of engrafting (low-weight group [LWG], n = 38) compared to a matched control group (n = 76) with a body weight of 10-15 kg, using data from the first 2 years post-transplant derived from the CERTAIN Registry. RESULTS: Patient survival was 97 and 100% in the LWG and control groups, respectively (P = 0.33), and death-censored graft survival was 100 and 95% in the LWG and control groups, respectively (P = 0.30). Estimated glomerular filtration rate at 2 years post-transplant was excellent and comparable between the groups (LWG 77.6 ± 34.9 mL/min/1.73 m2; control 74.8 ± 29.1 mL/min/1.73 m2; P = 0.68). The overall incidences of surgery-related complications (LWG 11%, control 23%; P = 0.12) and medical outcome measures (LWG 23%, control 36%, P = 0.17) were not significantly different between the groups. The medical outcome measures included transplant-related viral diseases (LWG 10%, control 21%; P = 0.20), acute rejection episodes (LWG 14%, control 29%; P = 0.092), malignancies (LWG 3%, control 0%; P = 0.33) and arterial hypertension (LWG 73%, control 67%; P = 0.57). CONCLUSIONS: These data suggest that RTx in low-weight children is a feasible option, at least in selected centers with appropriate surgical and medical expertise.