Diversity of kidney care referral pathways in national child health systems of 48 European countries.

Background: Primary, secondary and tertiary healthcare services in Europe create complex networks covering pediatric subspecialties, sociology, economics and politics. Two surveys of the European Society for Paediatric Nephrology (ESPN) in 1998 and 2017 revealed substantial disparities of kidney care among European countries. The purpose of the third ESPN survey is to further identify national differences in the conceptualization and organization of European pediatric kidney health care pathways during and outside normal working hours. Methods: In 2020, a questionnaire was sent to one leading pediatric nephrologist from 48 of 53 European countries as defined by the World Health Organization. In order to exemplify care pathways in pediatric primary care nephrology, urinary tract infection (UTI) was chosen. Steroid sensitive nephrotic syndrome (SSNS) was chosen for pediatric rare disease nephrology and acute kidney injury (AKI) was analyzed for pediatric emergency nephrology. Results: The care pathways for European children and young people with urinary tract infections were variable and differed during standard working hours and also during night-time and weekends. During daytime, UTI care pathways included six different types of care givers. There was a shift from primary care services outside standard working hours to general outpatient polyclinic and hospital services. Children with SNSS were followed up by pediatric nephrologists in hospitals in 69% of countries. Patients presenting with community acquired AKI were admitted during regular working hours to secondary or tertiary care hospitals. During nights and weekends, an immediate shift to University Children's Hospitals was observed where treatment was started by intensive care pediatricians and pediatric nephrologists. Conclusion: Gaps and fragmentation of pediatric health services may lead to the risk of delayed or inadequate referral of European children with kidney disease to pediatric nephrologists. The diversity of patient pathways outside of normal working hours was identified as one of the major weaknesses in the service chain.

Urine soluble TLR4 levels may contribute to predict urinary tract infection in children: the UTILISE Study.

BACKGROUND: One of the most common bacterial infections in childhood is urinary tract infection (UTI). Toll-like receptors (TLRs) contribute to immune response against UTI recognizing specific pathogenic agents. Our aim was to determine whether soluble TLR4 (sTLR4), soluble TLR5 (sTLR5) and interleukin 8 (IL-8) can be used as biomarkers to diagnose UTI. We also aimed to reveal the relationship between urine Heat Shock Protein 70 (uHSP70) and those biomarkers investigated in this study. METHODS: A total of 802 children from 37 centers participated in the study. The participants (n = 282) who did not meet the inclusion criteria were excluded from the study. The remaining 520 children, including 191 patients with UTI, 178 patients with non-UTI infections, 50 children with contaminated urine samples, 26 participants with asymptomatic bacteriuria and 75 healthy controls were included in the study. Urine and serum levels of sTLR4, sTLR5 and IL-8 were measured at presentation in all patients and after antibiotic treatment in patients with UTI. RESULTS: Urine sTLR4 was higher in the UTI group than in the other groups. UTI may be predicted using 1.28 ng/mL as cut-off for urine sTLR4 with 68% sensitivity and 65% specificity (AUC = 0.682). In the UTI group, urine sTLR4 levels were significantly higher in pyelonephritis than in cystitis (p < 0.0001). Post-treatment urine sTLR4 levels in the UTI group were significantly lower than pre-treatment values (p < 0.0001). CONCLUSIONS: Urine sTLR4 may be used as a useful biomarker in predicting UTI and subsequent pyelonephritis in children with UTI. A higher resolution version of the Graphical abstract is available as Supplementary information.

Complement gene mutations in children with C3 glomerulopathy: do they affect the response to mycophenolate mofetil?

BACKGROUND: C3 glomerulopathy (C3G) is a complement-mediated disease. Although genetic studies are not required for diagnosis, they are valuable for treatment planning and prognosis prediction. The aim of this study is to investigate the clinical phenotypes, kidney survival, and response to mycophenolate mofetil (MMF) treatment in pediatric C3G patients with and without mutations in complement-related genes. METHODS: Sixty pediatric C3G patients were included, divided into two groups based on complement-related gene mutations. Demographic and clinical-pathological findings, treatment modalities, and outcome data were compared, and Kaplan-Meier analysis was performed for kidney survival. RESULTS: Out of the 60 patients, 17 had mutations. The most common mutation was in the CFH gene (47%). The mean age at diagnosis was higher in the group with mutation (12.9 ± 3.6 vs. 11.2 ± 4.1 years, p = 0.039). While the patients without mutation most frequently presented with nephritic syndrome (44.2%), the mutation group was most likely to have asymptomatic urinary abnormalities (47.1%, p = 0.043). Serum parameters and histopathological characteristics were similar, but hypoalbuminemia was more common in patients without mutation. During 45-month follow-up,10 patients progressed to chronic kidney disease stage 5 (CKD5), with 4 having genetic mutation. The time to develop CKD5 was longer in the mutation group but not significant. MMF treatment had no effect on progression in either group. CONCLUSIONS: This study is the largest pediatric C3G study examining the relationship between genotype and phenotype. We showed that the mutation group often presented with asymptomatic urinary abnormalities, was diagnosed relatively late but was not different from the without mutation group in terms of MMF treatment response and kidney survival.

Clinical Predictors of Steroid Resistance in Childhood Nephrotic Syndrome.

We aimed to evaluate the clinical parameters, histopathological findings of nephrotic syndrome (NS) patients, and independent factors predicting steroid resistance in a single tertiary center. One hundred and sixty-two children (57 girls and 105 boys) with NS who were followed between 1998 and 2018 were analyzed in this retrospective cohort. The median (interquartile range; range) age and follow-up time were 4.9 (5.7; 0.1-16.8) and 5.5 (5.4; 0.1-20.3) years. A total of 82.7% of the patients were steroid-sensitive nephrotic syndrome (SSNS) and 17.3% were steroid-resistant nephrotic syndrome (SRNS). The median age at first presentation was lower in the SSNS group (P = .002). The most common histopathological findings were focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD). Hypertension and macroscopic and microscopic hematuria were higher in the SRNS group (P < .001). The age and microscopic hematuria were independent risk factors for steroid resistance (P = .019 and P = .002, respectively). Complement 3 (C3) was evaluated in 148 patients and found low in 7 patients who were subsequently diagnosed as membranoproliferative glomerulonephritis. There is still no better clinical predictor for steroid response than late age of onset and microscopic hematuria. Hypertension may also give a hint for potential steroid resistance.

Catastrophic antiphospholipid syndrome accompanied by complement regulatory gene mutation.

BACKGROUND: Antiphospholipid syndrome (APS), particularly the catastrophic antiphospholipid syndrome (CAPS), is one of the rare causes of thrombotic microangiopathy (TMA). CAPS is the most severe form of APS, especially when accompanied by complement dysregulation, causes progressive microvascular thrombosis and failure in multiple organs. In this report, a case of CAPS with TMA accompanied by a genetic defect in the complement system is presented. CASE: A 13-year-old girl was admitted to the hospital with oliguric acute kidney injury, nephrotic range proteinuria, Coombs positive hemolysis, refractory thrombocytopenia, a low serum complement C3 level and anti-nuclear antibody (ANA) positivity. The kidney biopsy was consistent with TMA. She was first diagnosed with primary APS with clinical and pathological findings and double antibody positivity. As initial treatments, plasmapheresis (PE) was performed and eculizumab was also administered following pulsesteroid and intravenous immunoglobulin treatments. Her renal functions recovered and she was followed up with mycophenolate mofetil, hydroxychloroquine, low dose prednisolone and low molecular weight heparin treatments. The patient presented with severe chest pain, vomiting and acute deterioration of renal functions a few months after the diagnosis of TMA. A CAPS attack was considered due to radiological findings consistent with multiple organ thrombosis and intravenous cyclophosphamide (CYC) was given subsequent to PE. After pulse CYC and PE treatments, her renal functions recovered, she is still being followed for stage-3 chronic kidney disease. Complement factor H-related protein I gene deletion was detected in the genetic study. CONCLUSIONS: The clinical course of complement mediated CAPS tends to be worse. Complement system dysregulation should be investigated in all CAPS patients, and eculizumab treatment should be kept in mind if detected.

Association between serum biomarkers and oral health status in children with chronic kidney disease: A cross-sectional study.

OBJECTIVES: The aim of this study was to investigate the association between serum biomarkers and oral health parameters in children with chronic kidney disease (CKD). MATERIALS AND METHODS: Serum hemoglobin, blood urea nitrogen, serum creatinine, calcium, parathormone, magnesium, and phosphorus levels were measured in 62 children with CKD aged between 4 and 17 years. Intraoral examinations of the patients were performed by two different pediatric dentists. Dental caries was assessed using the decayed-missing-filled-teeth (DMFT/dmft) indexes, and oral hygiene was assessed using the debris (DI), calculus (CI), and simplified oral hygiene (OHI-S) indexes. Spearman's rho coefficient and generalized linear modeling were used to examine the association between serum biomarkers and oral health parameters. RESULTS: The results of the study showed that there were negative and statistically significant correlations between serum hemoglobin and creatinine levels and dmft scores in pediatric patients with CKD (p = 0.021 and p = 0.019, respectively). Furthermore, blood urea nitrogen levels and DI and OHI-S scores (p = 0.047 and p = 0.050, respectively); serum creatinine levels and DI, CI, and OHI-S scores (p = 0.005, p = 0.047, p = 0.043, respectively); and parathormone levels and CI and OHI-S scores (p = 0.001 and p = 0.017, respectively) were found to be positively and statistically significantly related. CONCLUSIONS: There are associations between various serum biomarker levels and dental caries and oral hygiene parameters in pediatric patients with CKD. CLINICAL RELEVANCE: The impact of changes in serum biomarkers on oral and dental health is important for dentists' and medical professionals' approaches to patients' oral and systemic health.

Urinary DKK3 as a biomarker for short-term kidney function decline in children with chronic kidney disease: an observational cohort study.

BACKGROUND: Childhood-onset chronic kidney disease is a progressive condition that can have a major effect on life expectancy and quality. We evaluated the usefulness of the kidney tubular cell stress marker urinary Dickkopf-related protein 3 (DKK3) in determining the short-term risk of chronic kidney disease progression in children and identifying those who will benefit from specific nephroprotective interventions. METHODS: In this observational cohort study, we assessed the association between urinary DKK3 and the combined kidney endpoint (ie, the composite of 50% reduction of the estimated glomerular filtration rate [eGFR] or progression to end-stage kidney disease) or the risk of kidney replacement therapy (ie, dialysis or transplantation), and the interaction of the combined kidney endpoint with intensified blood pressure reduction in the randomised controlled ESCAPE trial. Moreover, urinary DKK3 and eGFR were quantified in children aged 3-18 years with chronic kidney disease and urine samples available enrolled in the prospective multicentre ESCAPE (NCT00221845; derivation cohort) and 4C (NCT01046448; validation cohort) studies at baseline and at 6-monthly follow-up visits. Analyses were adjusted for age, sex, hypertension, systolic blood pressure SD score (SDS), BMI SDS, albuminuria, and eGFR. FINDINGS: 659 children were included in the analysis (231 from ESCAPE and 428 from 4C), with 1173 half-year blocks in ESCAPE and 2762 in 4C. In both cohorts, urinary DKK3 above the median (ie, >1689 pg/mg creatinine) was associated with significantly greater 6-month eGFR decline than with urinary DKK3 at or below the median (-5·6% [95% CI -8·6 to -2·7] vs 1·0% [-1·9 to 3·9], p<0·0001, in ESCAPE; -6·2% [-7·3 to -5·0] vs -1·5% [-2·9 to -0·1], p<0·0001, in 4C), independently of diagnosis, eGFR, and albuminuria. In ESCAPE, the beneficial effect of intensified blood pressure control was limited to children with urinary DKK3 higher than 1689 pg/mg creatinine, in terms of the combined kidney endpoint (HR 0·27 [95% CI 0·14 to 0·55], p=0·0003, number needed to treat 4·0 [95% CI 3·7 to 4·4] vs 250·0 [66·9 to ∞]) and the need for kidney replacement therapy (HR 0·33 [0·13 to 0·85], p=0·021, number needed to treat 6·7 [6·1 to 7·2] vs 31·0 [27·4 to 35·9]). In 4C, inhibition of the renin-angiotensin-aldosterone system resulted in significantly lower urinary DKK3 concentrations (least-squares mean 12 235 pg/mg creatinine [95% CI 10 036 to 14 433] in patients not on angiotensin-converting enzyme inhibitors or angiotensin 2 receptor blockers vs 6861 pg/mg creatinine [5616 to 8106] in those taking angiotensin-converting enzyme inhibitors or angiotensin 2 receptor blockers, p<0·0001). INTERPRETATION: Urinary DKK3 indicates short-term risk of declining kidney function in children with chronic kidney disease and might allow a personalised medicine approach by identifying those who benefit from pharmacological nephroprotection, such as intensified blood pressure lowering. FUNDING: None.

Urinary HSP70 improves diagnostic accuracy for urinary tract infection in children: UTILISE study.

BACKGROUND: The accuracy of conventional urinalysis in diagnosing urinary tract infection (UTI) in children is limited, leading to unnecessary antibiotic exposure in a large fraction of patients. Urinary heat shock protein 70 (uHSP70) is a novel marker of acute urinary tract inflammation. We explored the added value of uHSP70 in discriminating UTI from other infections and conditions confused with UTI. METHODS: A total of 802 children from 37 pediatric centers in seven countries participated in the study. Patients diagnosed with UTI (n = 191), non-UTI infections (n = 178), contaminated urine samples (n = 50), asymptomatic bacteriuria (n = 26), and healthy controls (n = 75) were enrolled. Urine and serum levels of HSP70 were measured at presentation in all patients and after resolution of the infection in patients with confirmed UTI. RESULTS: Urinary (u)HSP70 was selectively elevated in children with UTI as compared to all other conditions (p < 0.0001). uHSP70 predicted UTI with 89% sensitivity and 82% specificity (AUC = 0.934). Among the 265 patients with suspected UTI, the uHSP70 > 48 ng/mL criterion identified the 172 children with subsequently confirmed UTI with 90% sensitivity and 82% specificity (AUC = 0.862), exceeding the individual diagnostic accuracy of leukocyturia, nitrite, and leukocyte esterase positivity. uHSP70 had completely normalized by the end of antibiotic therapy in the UTI patients. Serum HSP70 was not predictive. CONCLUSIONS: Urine HSP70 is a novel non-invasive marker of UTI that improves the diagnostic accuracy of conventional urinalysis. We estimate that rapid urine HSP70 screening could spare empiric antibiotic administration in up to 80% of children with suspected UTI. A higher resolution version of the Graphical abstract is available as Supplementary information.

Assessment of the oral health status of children with chronic kidney disease.

BACKGROUND: There are various oral symptoms related to the disease and its management in individuals with chronic kidney disease (CKD). The aim of the study was to investigate the oral health status of children with different stages of CKD, kidney transplant recipients (KTR), and healthy children. METHODS: A total of seventy-one children diagnosed with CKD and fifty-two healthy children were included in the study. Each patient was examined for dental caries by the decayed-missing-filled-teeth (DMFT/dmft) index and the International Caries Detection and Assessment System (ICDAS-II), developmental defects of enamel (DDE) by the DDE index, and oral hygiene by the debris (DI), calculus (CI), and simplified oral hygiene (OHI-S) indices. RESULTS: The median number of DMFT/dmft was 1.00 (interquartile range (IQR):1.00-4.00) in children with stage 1-3 CKD, 0.00 (IQR: 0.00-2.50) in stage 4-5 children, 0.00 (IQR: 1.00-3.00) in KTR, and 8.00 (IQR: 1.00-13.00) in healthy children. According to ICDAS-II categories, the percentage of children with severe caries was 53.8% in healthy children, while it was 44.4% in KTR, 25.9% in stage 1-3, and 11.4% in stage 4-5 children. While the percentage of children with DDE was 88.8% in KTR, 80% in stage 4-5, and 66.7% in stage 1-3 children, this rate was 44.2% in healthy children. The highest mean OHI-S score was observed in stage 4-5 children (2.10 ± 1.08), followed by KTR (1.46 ± 1.19), stage 1-3 (1.27 ± 0.61), and healthy children (0.45 ± 0.44), respectively. CONCLUSIONS: Compared to healthy children, children with CKD had more debris accumulation, calculus formation, and more DDE but a lower severity of dental caries. A higher resolution version of the Graphical abstract is available as Supplementary information.

Evaluation of the Claria sharesource system from the perspectives of patient/caregiver, physician, and nurse in children undergoing automated peritoneal dialysis.

BACKGROUND: Automated peritoneal dialysis (APD) is increasingly preferred worldwide. By using a software application (Homechoice with Claria sharesource system (CSS)) with a mod-M added to the APD device, details of the home dialysis treatment become visible for PD nurses and physicians, allowing for close supervision. We aimed to evaluate the perceptions of patients/caregivers, PD nurses, and physicians about the advantages and disadvantages of CSS. METHODS: Three different web-based questionnaires for patients/caregivers, nurses, and physicians were sent to 15 pediatric nephrology centers with more than 1 year of experience with CSS. RESULTS: Respective questionnaires were answered by 30 patients/caregivers, 22 pediatric nephrologists, and 15 PD nurses. Most of the nurses and physicians (87% and 73%) reported that CSS improved patient monitoring. A total of 73% of nurses suggested that CCS is not well known by physicians, while half of them reported reviewing CSS data for all patients every morning. Sixty-eight percent of physicians thought that CSS helps save time for both patients/caregivers and healthcare providers by reducing visits. However, only 20% of patients/caregivers reported reduced hospital visits. A total of 90% of patients/caregivers reported that being under constant monitoring made them feel safe, and 83% stated that the patient's sleep quality improved. CONCLUSIONS: A remote monitoring APD system, CSS, can be successfully applied with children for increased adherence to dialysis prescription by giving shared responsibility and may help increase the patient's quality of life. This platform is more commonly used by nurses than physicians. Its potential benefits should be evaluated in further well-designed clinical studies with larger patient groups. A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinical and genetic characterization of children with cubilin variants.

BACKGROUND: Cubilin is one of the receptor proteins responsible for reabsorption of albumin in proximal tubules and is encoded by the CUBN gene. We aimed to evaluate clinical and genetic characterization of six patients with proteinuria who had CUBN mutations. METHODS: Patients' characteristics, serum creatinine, albumin, vitamin B12 levels, urine analysis, spot urine protein/creatinine, microalbumin/creatinine, beta-2 microglobulin/creatinine ratios, estimated glomerular filtration rates (eGFR), treatments, kidney biopsies, and genetic analyses were evaluated. RESULTS: Six patients (2 female, 4 male) with an incidental finding of proteinuria were evaluated. Mean admission age and follow-up time were 7.3 ± 2.9 and 6.5 ± 5.6 years, respectively. Serum albumin, creatinine, and eGFR were normal; urine analysis revealed no hematuria, and C3, C4, ANA, and anti-DNA were negative; kidney ultrasonography was normal for all patients. Urine protein/creatinine was 0.9 ± 0.3 mg/mg, and microalbumin was high in all patients. Serum vitamin B12 was low in two patients and normal in four. Kidney biopsy was performed in four patients, three demonstrated normal light microscopy, and there was one focal segmental glomerulosclerosis (FSGS). Genetic tests revealed four homozygous and two compound heterozygous mutations in the C-terminal part of cubilin. All patients had normal eGFR and still had non-nephrotic range proteinuria at last visit. CONCLUSIONS: CUBN gene mutations should be considered in patients with isolated non-nephrotic range proteinuria and normal kidney function. Diagnosing these patients, who are thought to have a better prognosis, is important in terms of avoiding unnecessary treatment and predicting prognosis. CUBN gene mutations may also present as FSGS which extends the spectrum of renal manifestation of these patients. A higher resolution version of the Graphical abstract is available as Supplementary information.

Collapsing Glomerulopathy in a Patient with a TRPC6 Mutation Presenting as Rapidly Progressive Glomerulonephritis: A Case Report and Review of the Literature.

Collapsing glomerulopathy (CG) is a proliferative disease characterized by segmental or global wrinkling of the glomerular basement membrane and the formation of pseudocrescents, whereas focal segmental glomerulosclerosis (FSGS) is characterized by podocytopenia, and focal and segmental sclerosis of the glomeruli. Mutations in NPHS1, NPHS2, WT1, PLCE1, CD2AP, ACTN4, and TRPC6 have been reported in steroid-resistant FSGS patients. The mutations p.R895C and p.R895L in Exon 13 are the only ones in TRPC6 causing CG reported to date. Here, we present the case of a 17-year-old male patient with a collapsing variant of familial FSGS caused by a mutation in TRPC6 (p.R895C) who presented with rapidly progressive (crescentic) and proliferative glomerulonephritis.

Phenotypic and genotypic characteristics of children with Bartter syndrome.

INTRODUCTION: Bartter syndrome (BS) is a group of autosomal-recessive tubular disorders and it is classified into five genetic subtypes. BS can also be classified by phenotype (antenatal, classic). Patients with mutations in the same gene can present different phenotypes. In the present study, target gene sequencing was performed to evaluate the genotype-phenotype relationship. METHODS: Biochemical, clinical and renal ultrasonography results were collected at presentation and the last clinic visit. Genetic analyses were performed. The findings of patients with classical BS (cBS) and antenatal BS (aBS) at presentation and the last visit were compared. RESULTS: Our study included 21 patients (12 female, 57.1%) from 20 families with BS. The median age at diagnosis was 8 months and the median follow-up period was 39 months. The most frequent complaint was growth failure. We have found 18 different types of mutations in four genes, including nine in the CLCNKB gene, seven in the SLCA12A1 gene, one in the KCNJ1 gene and one in the BSND gene. In ten patients, nine different types of CLCNKB gene mutations were detected, five of them were novel. Seven different mutations in the SLC12A1 gene were detected in eight patients, five of them were novel. Compared to patients with aBS and cBS, prematurity was significantly higher in the group with aBS. Nephrocalcinosis was present in only one patient with cBS, all the ten hypercalciuric patients with aBS had nephrocalcinosis at the time of diagnosis and the last visit. The mean height standard deviation score (SDS) of patients with aBS were significantly lower than the cBS group at the time of presentation. The mean weight SDS at the time of presentation was worse in patients with aBS than in patients with cBS. The mean plasma potassium and chloride concentrations were significantly lower in the patients with cBS at the time of diagnosis. CONCLUSIONS: This investigation revealed the mutation characteristics and phenotype-genotype relationship of our patients and provided valuable data for genetic counseling.

Molecular Aspects of Distal Kidney Tubular Acidosis in Children, Its Long-Term Outcome, and Relationship with Hyperammonemia.

OBJECTIVE: We aimed to present the characteristics, genetic analysis results, long-term progno- sis of our patients with distal kidney tubular acidosis, and the relationship between hyperam- monemia and distal kidney tubular acidosis. MATERIALS AND METHODS: Biochemical, clinical, and imaging findings were collected at presen- tation and the last clinic visit, and results of the genetic analysis were recorded. RESULTS: Our study included 9 patients (3 female, 33%). The median age at diagnosis was 3 months, and the median follow-up period was 111 months. Height standard deviation scores were less than -2 in 4 (44%) patients at presentation and in 3 (33%) at the last clinic visit. The median estimated glomerular filtration rate was 98 mL/min/1.73 m2 at presentation and 126 mL/min/1.73 m2 at the last clinic visit. We have found 8 different types of mutations of 2 genes, including 6 in the ATP6V0A4 gene, 2 in the SLCA4A1 gene, and 2 of them were novel. At the time of presentation, nephrocalcinosis and hypercalciuria were present in all our patients, but at the last visit, only 1 patient had hypercalciuria. Sensorineural hearing loss was found in 4 of our patients with a mutation in the ATP6V0A4 gene. Serum ammonia levels were found to be high in 3 patients with mutations in the ATP6V0A4 gene. CONCLUSION: Adequate metabolic control is essential for optimal growth and preserved kidney function in distal kidney tubular acidosis patients. Distal kidney tubular acidosis may be associ- ated with hyperammonemia. We recommend keeping potassium levels at high-normal levels to reduce ammonia levels, especially in the absence of acidosis.

Comparison of infants and children with urolithiasis: a large case series.

We evaluated the demographic features, etiologic risk factors, treatment strategies, and outcome of the infants and children with urolithiasis (UL). A retrospective multicenter study was conducted including 23 Pediatric Nephrology centers in Turkey. The medical records of 2513 children with UL were reviewed. One thousand, three hundred and four boys and 1209 girls (1.1:1) were reported. The mean age at diagnosis was 39.5 ± 35 months (0.4-231 months), and 1262 patients (50.2%) were in the first year of life (infants). Most of the cases with infantile UL were diagnosed incidentally. Microlithiasis (< 3 mm) was found in 794 patients (31.6%), and 64.5% of the patients with microlithiasis were infants. Stones were located in the pelvis-calyces in 63.2% (n: 1530) of the cases. The most common stone type was calcium oxalate (64.6%). Hypocitraturia was the most common metabolic risk factor (MRF) in children older than 12 months, but in infancy, hypercalciuria was more common. Fifty-five percent of the patients had received at least one medical treatment, mostly potassium citrate. At the end of a year's follow-up, most of the patients with microlithiasis (85%) showed spontaneous remission. The rate of spontaneous stone resolution in infants was higher than in children. Spontaneous remission rate was higher in cases with MRF ( - ) stones than in MRF ( +) stones. However, remission rate with medical treatment was higher in cases with MRF ( +) stones. This study represents the results of a large series of infants and children with UL and showed that there are several differences such as underlying metabolic and anatomic abnormalities, clinical course, and stone remission rates between infants and children with urinary stone disease.

Parathyroid hormone and phosphate homeostasis in patients with Bartter and Gitelman syndrome: an international cross-sectional study.

BACKGROUND: Small cohort studies have reported high parathyroid hormone (PTH) levels in patients with Bartter syndrome and lower serum phosphate levels have anecdotally been reported in patients with Gitelman syndrome. In this cross-sectional study, we assessed PTH and phosphate homeostasis in a large cohort of patients with salt-losing tubulopathies. METHODS: Clinical and laboratory data of 589 patients with Bartter and Gitelman syndrome were provided by members of the European Rare Kidney Diseases Reference Network (ERKNet) and the European Society for Paediatric Nephrology (ESPN). RESULTS: A total of 285 patients with Bartter syndrome and 304 patients with Gitelman syndrome were included for analysis. Patients with Bartter syndrome type I and II had the highest median PTH level (7.5 pmol/L) and 56% had hyperparathyroidism (PTH >7.0 pmol/L). Serum calcium was slightly lower in Bartter syndrome type I and II patients with hyperparathyroidism (2.42 versus 2.49 mmol/L; P = .038) compared to those with normal PTH levels and correlated inversely with PTH (rs -0.253; P = .009). Serum phosphate and urinary phosphate excretion did not correlate with PTH. Overall, 22% of patients had low serum phosphate levels (phosphate-standard deviation score < -2), with the highest prevalence in patients with Bartter syndrome type III (32%). Serum phosphate correlated with tubular maximum reabsorption of phosphate/glomerular filtration rate (TmP/GFR) (rs 0.699; P < .001), suggesting renal phosphate wasting. CONCLUSIONS: Hyperparathyroidism is frequent in patients with Bartter syndrome type I and II. Low serum phosphate is observed in a significant number of patients with Bartter and Gitelman syndrome and appears associated with renal phosphate wasting.

COVID-19 in pediatric patients undergoing chronic dialysis and kidney transplantation.

The study aims to present the incidence of COVID-19 in pediatric patients undergoing renal replacement therapy (RRT) and to compare the severity and outcomes of the disease between the dialysis and kidney transplant (KTx) groups. This multicenter observational study was conducted between 1 April and 31 December 2020 in Istanbul. Members of the Istanbul branch of the Turkish Pediatric Nephrology Association were asked to report all confirmed cases of COVID-19 who were on RRT, as well as the number of prevalent RRT patients under the age of 20. A total of 46 confirmed cases of COVID-19 were reported from 12 centers, of which 17 were dialysis patients, and 29 were KTx recipients. Thus, the incidence rate of COVID-19 was 9.3% among dialysis patients and 9.2% among KTx recipients over a 9-month period in Istanbul. Twelve KTx recipients and three dialysis patients were asymptomatic (p = 0.12). Most of the symptomatic patients in both the dialysis and KTx groups had a mild respiratory illness. Only two patients, one in each group, experienced a severe disease course, and only one hemodialysis patient had a critical illness that required mechanical ventilation. In the entire cohort, one hemodialysis patient with multiple comorbidities died.Conclusion: While most cases are asymptomatic or have a mild disease course, pediatric patients undergoing dialysis and a kidney transplant are at increased risk for COVID-19. What is Known: • In adult population, both dialysis patients and kidney transplant recipients are at increased risk for severe illness of COVID-19 and have higher mortality rate. • Children with kidney transplantation are not at increased risk for COVID-19 and most have mild disease course. • Data on children on dialysis are scarce. What is New: • Pediatric patients undergoing dialysis and kidney transplantation have an increased risk for COVID-19. • Most patients undergoing renal replacement therapy either on dialysis or transplanted develop asymptomatic or mild COVID-19 disease with a favorable outcome.

Findings from 4C-T Study demonstrate an increased cardiovascular burden in girls with end stage kidney disease and kidney transplantation.

Mortality in children with kidney failure is higher in girls than boys with cardiovascular complications representing the most common causes of death. Pulse wave velocity (PWV), a measure of vascular stiffness, predicts cardiovascular mortality in adults. Here, PWV in children with kidney failure undergoing kidney replacement therapy was investigated to determine sex differences and potential contributing factors. Two-hundred thirty-five children (80 girls; 34%) undergoing transplantation (150 pre-emptive, 85 with prior dialysis) having at least one PWV measurement pre- and/or post-transplantation from a prospective cohort were analyzed. Longitudinal analyses (median/maximum follow-up time of 6/9 years) were performed for PWV z-scores (PWVz) using linear mixed regression models and further stratified by the categories of time: pre-kidney replacement therapy and post-transplantation. PWVz significantly increased by 0.094 per year and was significantly higher in girls (PWVz +0.295) compared to boys, independent of the underlying kidney disease. During pre-kidney replacement therapy, an average estimated GFR decline of 4 ml/min/1.73 m2 per year was associated with a PWVz increase of 0.16 in girls only. Higher diastolic blood pressure and low density lipoprotein were independently associated with higher PWVz during pre-kidney replacement therapy in both sexes. In girls post-transplantation, an estimated GFR decline of 4ml/min/1.73m2 per year pre-kidney replacement therapy and a longer time (over 12 months) to transplantation were significantly associated with higher PWVz of 0.22 and of 0.57, respectively. PWVz increased further after transplantation and was positively associated with time on dialysis and diastolic blood pressure in both sexes. Thus, our findings demonstrate that girls with advanced chronic kidney disease are more susceptible to develop vascular stiffening compared to boys, this difference persist after transplantation and might contribute to higher mortality rates seen in girls with kidney failure.

COVID-19 in pediatric nephrology centers in Turkey.

BACKGROUND: There is limited data on COVID-19 disease in children with kidney disease. We aimed to investigate the characteristics and prognosis of COVID-19 in pediatric nephrology patients in Turkey. METHODS: This was a national, multicenter, retrospective cohort study based on an online survey evaluating the data between 11th March 2020 and 11th March 2021 as an initial step of a detailed pediatric nephrology COVID-19 registry. RESULTS: Two hundred and three patients (89 girls and 114 boys) were diagnosed with COVID-19. One-third of these patients (36.9%) were between 10-15 years old. Half of the patients were on kidney replacement therapy: kidney transplant (KTx) recipients (n = 56, 27.5%), patients receiving chronic hemodialysis (n = 33, 16.3%) and those on peritoneal dialysis (PD) (n = 18, 8.9%). Fifty-four (26.6%) children were asymptomatic. Eighty-two (40.3%) patients were hospitalized and 23 (28%) needed intensive care unit admission. Fifty-five percent of the patients were not treated, while the remaining was given favipiravir (20.7%), steroid (16.3%), and hydroxychloroquine (11.3%). Acute kidney injury developed in 19.5% of hospitalized patients. Five (2.4%) had MIS-C. Eighty-three percent of the patients were discharged without any apparent sequelae, while 7 (3.4%) died. One hundred and eight health care staff were infected during the study period. DISCUSSION: COVID-19 was most commonly seen in patients who underwent KTx and received HD. The combined immunosuppressive therapy and frequent exposure to the hospital setting may increase these patients' susceptibility. Staff infections before vaccination era were alarming, various precautions should be taken for infection control, particularly optimal vaccination coverage.