Assessment of mineral and bone biomarkers highlights a high frequency of hypercalciuria in asymptomatic healthy teenagers

AIM

Assessment of mineral metabolism is complex in paediatrics.

METHODS

We assessed the evolution of the main mineral and bone biomarkers (total/bone alkaline phosphatase ALP/BAP, β-crosslaps, osteocalcin, sclerostin, C-terminal and intact FGF23) in 100 healthy teenagers (10-18 years, 50 boys).

RESULTS

At a mean age of 13.7 ± 2.2 years, phosphatemia, tubular phosphate reabsorption, ALP and BAP significantly decreased along puberty in both genders, whilst parathyroid hormone (PTH), 25-vitamin D (25D), FGF23, plasma calcium and urinary calcium were not modified. In girls, osteocalcin, β-crosslaps and sclerostin significantly decreased at the end of puberty. Calciuria above the crystallisation threshold (>3.8 mmol/L) and urinary calcium/creatinine ratio >0.7 mmol/mmol were found in 39% and 6% of subjects, respectively. Multivariable analyses showed that renal function and PTH were significant predictors of calciuria and urinary calcium/creatinine, whilst 25D remained a predictor only of urinary calcium/creatinine ratio.

CONCLUSION

Using the most recent assays, this study provides data for mineral/bone biomarkers across puberty and highlights the risk of hyper-calciuria in apparent asymptomatic healthy teenagers, not related to calcium intake but rather to 25D. Future studies are required to dissect the underlying mechanisms increasing calciuria and prevent nephrolithiasis as early as during childhood.

RMND1 mutations in two siblings: Severe renal hypoplasia but different levels of extrarenal abnormality severity: The ethics of decision making

Mutations in the RMND1 gene, causing defects in the mitochondrial respiratory chain, result in a very heterozygous phenotype. Currently there are 36 cases reported in the literature. We report two siblings from a non-consanguineous family who were severely affected by a compound heterozygous RMND1 mutation that had not been described previously and were treated differently for their end-stage renal disease. We summarize all previous published cases and focus on the importance of extrarenal comorbidities in the context of therapeutic decision making (renal replacement therapy) and its ethical relevance.

Haemodiafiltration does not lower protein-bound uraemic toxin levels compared with haemodialysis in a paediatric population

Background

Haemodiafiltration (HDF) is accepted to effectively lower plasma levels of middle molecules in the long term, while data are conflicting with respect to the additive effect of convection on lowering protein-bound uraemic toxins (PBUTs). Here we compared pre-dialysis β2-microglobulin (β2M) and PBUT levels and the percentage of protein binding (%PB) in children on post-dilution HDF versus conventional high- (hf) or low-flux (lf) haemodialysis (HD) over 12 months of treatment.

Methods

In a prospective multicentre, non-randomized parallel-arm intervention study, pre-dialysis levels of six PBUTs and β2M were measured in children (5–20 years) on post-HDF (n = 37), hf-HD (n = 42) and lf-HD (n = 18) at baseline and after 12 months. Analysis of variance was used to compare levels and %PB in post-HDF versus conventional hf-HD and lf-HD cross-sectionally at 12 months and longitudinal from baseline to 12 months.

Results

For none of the PBUTs, no difference was found in either total and free plasma levels or %PB between post-HDF versus the hf-HD and lf-HD groups. Children treated with post-HDF had lower pre-dialysis β2M levels [median 23.2 (21.5; 26.6) mg/dL] after 12 months versus children on hf-HD [P<0.01; 35.2 (29.3; 41.2) mg/dL] and children on lf-HD [P<0.001; 47.2 (34.3; 53.0) mg/dL]. While β2M levels remained steady in the hf-HD and lf-HD group, a decrease in β2M was demonstrated for children on post-HDF (P<0.01).

Conclusions

While post-HDF successfully decreased β2M, no additive effect on PBUT over 12 months of treatment was found. PBUT removal is complex and hampered by several factors. In children, these factors might be different from adults and should be explored in future research.

Growth and nutritional management of children on peritoneal dialysis

Stunting and malnutrition are common in children with chronic kidney disease and increase with the degree of impairment to be maximal in children at the dialysis stage, leading to a risk of excess mortality. Despite many advances in the field of pediatric dialysis, small size in adulthood remains very common in this population. The origin of malnutrition and stunting is complex and multifactorial. In infants on peritoneal dialysis, insufficient nutritional intake is recognized as a major barrier to adequate growth. The diagnostic approach to undernutrition and stunting in peritoneal dialysis requires the use of several elements: an interrogation, a clinical examination, and various complementary examinations. Due to the multifactorial aspect of the nutritional and statural status of the child, several therapeutic axes are to be taken into account, namely a nutritional treatment adapted to the needs of the child, a treatment by growth hormone, and an optimization of dialysis to allow optimal metabolic control.

Neutral pH and low-glucose degradation product dialysis fluids induce major early alterations of the peritoneal membrane in children on peritoneal dialysis

The effect of peritoneal dialysates with low-glucose degradation products on peritoneal membrane morphology is largely unknown, with functional relevancy predominantly derived from experimental studies. To investigate this, we performed automated quantitative histomorphometry and molecular analyses on 256 standardized peritoneal and 172 omental specimens from 56 children with normal renal function, 90 children with end-stage kidney disease at time of catheter insertion, and 82 children undergoing peritoneal dialysis using dialysates with low-glucose degradation products. Follow-up biopsies were obtained from 24 children after a median peritoneal dialysis of 13 months. Prior to dialysis, mild parietal peritoneal inflammation, epithelial-mesenchymal transition and vasculopathy were present. After up to six and 12 months of peritoneal dialysis, blood microvessel density was 110 and 93% higher, endothelial surface area per peritoneal volume 137 and 95% greater, and submesothelial thickness 23 and 58% greater, respectively. Subsequent peritoneal changes were less pronounced. Mesothelial cell coverage was lower and vasculopathy advanced, whereas lymphatic vessel density was unchanged. Morphological changes were accompanied by early fibroblast activation, leukocyte and macrophage infiltration, diffuse podoplanin presence, epithelial mesenchymal transdifferentiation, and by increased proangiogenic and profibrotic cytokine abundance. These transformative changes were confirmed by intraindividual comparisons. Peritoneal microvascular density correlated with peritoneal small-molecular transport function by uni- and multivariate analysis. Thus, in children on peritoneal dialysis neutral pH dialysates containing low-glucose degradation products induce early peritoneal inflammation, fibroblast activation, epithelial-mesenchymal transition and marked angiogenesis, which determines the PD membrane transport function.

Quality of life in adolescents with chronic kidney disease who initiate haemodialysis treatment

BACKGROUND

To describe the quality of life of adolescents initiating haemodialysis, to determine the factors associated with quality of life, and to assess coping strategies and their impact on quality of life.

METHODS

All adolescents initiating haemodialysis between September 2013 and July 2015 in French paediatric haemodialysis centres were included. Quality of life data were collected using the "Vécu et Santé Perçue de l'Adolescent et l'Enfant" questionnaire, and coping data were collected using the Kidcope questionnaire. Adolescent's quality of life was compared with age- and sex-matched French control.

RESULTS

Thirty-two adolescents were included. Their mean age was 13.9 ± 2.0 years. The quality of life score was lowest in leisure activities and highest in relationships with medical staff. Compared with the French control, index, energy-vitality, relationships with friends, leisure activities and physical well-being scores were significantly lower in haemodialysis population. In multivariate analyses, active coping was positively associated with quality of life and especially with energy-vitality, relationships with parents and teachers, and school performance. In contrast, avoidant and negative coping were negatively associated with energy-vitality, psychological well-being and body image for avoidant coping, and body image and relationships with medical staff for negative coping.

CONCLUSIONS

The quality of life of haemodialysis adolescents, and mainly the dimensions of leisure activities, physical well-being, relationships with friends and energy-vitality, were significantly altered compared to that of the French population. The impact of coping strategies on quality of life seems to be important. Given the importance of quality of life and coping strategies in adolescents with chronic disease, health care professionals should integrate these aspects into care management.

Vascular Access Choice, Complications, and Outcomes in Children on Maintenance Hemodialysis: Findings From the International Pediatric Hemodialysis Network (IPHN) Registry

RATIONALE & OBJECTIVE

Arteriovenous fistulas (AVFs) have been recommended as the preferred vascular access for pediatric patients on maintenance hemodialysis (HD), but data comparing AVFs with other access types are scant. We studied vascular access choice, placement, complications, and outcomes in children.

STUDY DESIGN

Prospective observational cohort study.

SETTING & PARTICIPANTS

552 children and adolescents from 27 countries on maintenance HD followed up prospectively by the International Pediatric HD Network (IPHN) Registry between 2012 and 2017.

PREDICTOR

Type of vascular access: AVF, central venous catheter (CVC), or arteriovenous graft.

OUTCOME

Infectious and noninfectious vascular access complication rates, dialysis performance, biochemical and hematologic parameters, and clinical outcomes.

ANALYTICAL APPROACH

Univariate and multivariable linear mixed models, generalized linear mixed models, and proportional hazards models; cumulative incidence functions.

RESULTS

During 314 cumulative patient-years, 628 CVCs, 225 AVFs, and 17 arteriovenous grafts were placed. One-third of the children with an AVF required a temporary CVC until fistula maturation. Vascular access choice was associated with age and expectations for early transplantation. There was a 3-fold higher living related transplantation rate and lower median time to transplantation of 14 (IQR, 6-23) versus 20 (IQR, 14-36) months with CVCs compared with AVFs. Higher blood flow rates and Kt/V_urea were achieved with AVFs than with CVCs. Infectious complications were reported only with CVCs (1.3/1,000 catheter-days) and required vascular access replacement in 47%. CVC dysfunction rates were 2.5/1,000 catheter-days compared to 1.2/1,000 fistula-days. CVCs required 82% more revisions and almost 3-fold more vascular access replacements to a different site than AVFs (P<0.001).

LIMITATIONS

Clinical rather than population-based data.

CONCLUSIONS

CVCs are the predominant vascular access choice in children receiving HD within the IPHN. Age-related anatomical limitations and expected early living related transplantation were associated with CVC use. CVCs were associated with poorer dialysis efficacy, higher complication rates, and more frequent need for vascular access replacement. Such findings call for a re-evaluation of pediatric CVC use and practices.

Efficacy and safety of recombinant growth hormone treatment in children with growth retardation related to long-term glucocorticosteroid therapy

OBJECTIVE

To evaluate safety and efficacy of recombinant human growth hormone treatment in children on long-term glucocorticoid therapy.

METHODS

A 5-year prospective open-label study included children on glucocorticoid therapy with either standard deviation score (SDS)<-2 for height for chronological age (CA) if naïve to growth hormone treatment, or annual growth rate≥0 SDS for CA if currently receiving growth hormone.

RESULTS

Ninety-eight patients began treatment, 63 discontinued; 59 were analyzed for safety and 58 for efficacy. There was male predominance (78.0%). Median age was 13.0 years. Median height screening was 136.0cm (range, 95.1-159.7cm). Mean SDS for height for CA in the efficacy analysis set was -2.91±1.19 (range, -7.49 to -0.96). Mean growth hormone dose was 0.4, 0.4, 0.4 and 0.3mg/kg/week at month 0, M12, M24, and M36, respectively. Primary analysis of change in SDS for height for CA from baseline to M36 showed a significant increase of 0.80±1.03. Twenty patients in the safety analysis set had≥1 treatment-emergent adverse event (TEAE) related to study treatment. Two patients experienced serious treatment-related TEAEs: 1 case of poor compliance, and 1 of mild hyperglycemia, both already observed under growth hormone treatment.

CONCLUSION

This study suggests that growth hormone treatment could be effective in increasing height in children on long-term glucocorticoid treatment with a safety profile comparable to that in approved rhGH treatment indications.

CLINICAL TRIAL REGISTRATION

NCT00163189.

Global Variation of Nutritional Status in Children Undergoing Chronic Peritoneal Dialysis: A Longitudinal Study of the International Pediatric Peritoneal Dialysis Network

While children approaching end-stage kidney disease (ESKD) are considered at risk of uremic anorexia and underweight they are also exposed to the global obesity epidemic. We sought to investigate the variation of nutritional status in children undergoing chronic peritoneal dialysis (CPD) around the globe. The distribution and course of body mass index (BMI) standard deviation score over time was examined prospectively in 1001 children and adolescents from 35 countries starting CPD who were followed in the International Pediatric PD Network (IPPN) Registry. The overall prevalence of underweight, and overweight/obesity at start of CPD was 8.9% and 19.7%, respectively. Underweight was most prevalent in South and Southeast Asia (20%), Central Europe (16.7%) and Turkey (15.2%), whereas overweight and obesity were most common in the Middle East (40%) and the US (33%). BMI SDS at PD initiation was associated positively with current eGFR and gastrostomy feeding prior to PD start. Over the course of PD BMI SDS tended to increase on CPD in underweight and normal weight children, whereas it decreased in initially overweight patients. In infancy, mortality risk was amplified by obesity, whereas in older children mortality was markedly increased in association with underweight. Both underweight and overweight are prevalent in pediatric ESKD, with the prevalence varying across the globe. Late dialysis start is associated with underweight, while enteral feeding can lead to obesity. Nutritional abnormalities tend to attenuate with time on dialysis. Mortality risk appears increased with obesity in infants and with underweight in older children.

Effects of Hemodiafiltration versus Conventional Hemodialysis in Children with ESKD: The HDF, Heart and Height Study

BACKGROUND

Hypertension and cardiovascular disease are common in children undergoing dialysis. Studies suggest that hemodiafiltration (HDF) may reduce cardiovascular mortality in adults, but data for children are scarce.

METHODS

The HDF, Heart and Height study is a nonrandomized observational study comparing outcomes on conventional hemodialysis (HD) versus postdilution online HDF in children. Primary outcome measures were annualized changes in carotid intima-media thickness (cIMT) SD score and height SD score.

RESULTS

We enrolled 190 children from 28 centers; 78 on HD and 55 on HDF completed 1-year follow-up. The groups were comparable for age, dialysis vintage, access type, dialysis frequency, blood flow, and residual renal function. At 1 year, cIMT SD score increased significantly in children on HD but remained static in the HDF cohort. On propensity score analysis, HD was associated with a +0.47 higher annualized cIMT SD score compared with HDF. Height SD score increased in HDF but remained static in HD. Mean arterial pressure SD score increased with HD only. Factors associated with higher cIMT and mean arterial pressure SD-scores were HD group, higher ultrafiltration rate, and higher β2-microglobulin. The HDF cohort had lower β2-microglobulin, parathyroid hormone, and high-sensitivity C-reactive protein at 1 year; fewer headaches, dizziness, or cramps; and shorter postdialysis recovery time.

CONCLUSIONS

HDF is associated with a lack of progression in vascular measures versus progression with HD, as well as an increase in height not seen in the HD cohort. Patient-related outcomes improved among children on HDF correlating with improved BP control and clearances. Confirmation through randomized trials is required.

Effect of haemodiafiltration vs conventional haemodialysis on growth and cardiovascular outcomes in children - the HDF, heart and height (3H) study

BACKGROUND

Cardiovascular disease is prevalent in children on dialysis and accounts for almost 30% of all deaths. Randomised trials in adults suggest that haemodiafiltration (HDF) with high convection volumes is associated with reduced cardiovascular mortality compared to high-flux haemodialysis (HD); however paediatric data are scarce. We designed the haemodiafiltration, heart and height (3H) study to test the hypothesis that children on HDF have an improved cardiovascular risk profile, growth and nutritional status and quality of life, compared to those on conventional HD. We performed a non-randomised parallel-arm intervention study within the International Paediatric Haemodialysis Network Registry comparing children on HDF and conventional HD to determine annualised change in cardiovascular end-points and growth. Here we present the 3H study design and baseline characteristics of the study population.

METHODS

190 children were screened and 177 (106 on HD and 71 on HDF) recruited from 28 centres in 10 countries. There was no difference in age, underlying diagnosis, comorbidities, previous dialysis therapy, dialysis vintage, residual renal function, type of vascular access or blood flow between HD and HDF groups. High flux dialysers were used in 63% of HD patients and ultra-pure water was available in 52%. HDF patients achieved a median convection volume of 13.3 L/m²; this was associated with the blood flow rate only ((p = 0.0004, r = 0.42) and independent of access type (p = 0.38).

DISCUSSION

This is the largest study on dialysis outcomes in children that involves deep phenotyping across a wide range of cardiovascular, anthropometric, nutritional and health-related quality of life measures, to test the hypothesis that HDF leads to improved cardiovascular and growth outcomes compared to conventional HD.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02063776 . The trial was prospectively registered on the 14 Feb 2014.

Risk Factors for Early Dialysis Dependency in Autosomal Recessive Polycystic Kidney Disease

OBJECTIVE

To identify prenatal, perinatal, and postnatal risk factors for dialysis within the first year of life in children with autosomal recessive polycystic kidney disease (ARPKD) as a basis for parental counseling after prenatal and perinatal diagnosis.

STUDY DESIGN

A dataset comprising 385 patients from the ARegPKD international registry study was analyzed for potential risk markers for dialysis during the first year of life.

RESULTS

Thirty-six out of 385 children (9.4%) commenced dialysis in the first year of life. According to multivariable Cox regression analysis, the presence of oligohydramnios or anhydramnios, prenatal kidney enlargement, a low Apgar score, and the need for postnatal breathing support were independently associated with an increased hazard ratio for requiring dialysis within the first year of life. The increased risk associated with Apgar score and perinatal assisted breathing was time-dependent and vanished after 5 and 8 months of life, respectively. The predicted probabilities for early dialysis varied from 1.5% (95% CI, 0.5%-4.1%) for patients with ARPKD with no prenatal sonographic abnormalities to 32.3% (95% CI, 22.2%-44.5%) in cases of documented oligohydramnios or anhydramnios, renal cysts, and enlarged kidneys.

CONCLUSIONS

This study, which identified risk factors associated with onset of dialysis in ARPKD in the first year of life, may be helpful in prenatal parental counseling in cases of suspected ARPKD.

Pharmacogenetics of post-transplant diabetes mellitus in children with renal transplantation treated with tacrolimus

BACKGROUND

Post-transplant diabetes mellitus (PTDM) is a major complication of immunosuppressive therapy, with many risk factors reported in adults with renal transplantation. The objective of this study was to investigate potential non-genetic and genetic risk factors of PTDM in children with renal transplantation treated with tacrolimus.

METHODS

A national database was screened for patients developing PTDM within 4 years following tacrolimus introduction. PTDM was defined as glucose disorder requiring anti-diabetic treatment. PTDM patients were matched to "non-PTDM" control transplanted children according to age, gender, and duration of post-transplant follow-up. Patients were genotyped for six selected genetic variants in POR*28 (rs1057868), PPARa (rs4253728), CYP3A5 (rs776746), VDR (rs2228570 and rs731236), and ABCB1 (rs1045642) genes, implicated in glucose homeostasis and tacrolimus disposition.

RESULTS

Among the 98 children with renal transplantation enrolled in this multicentre study, 18 developed PTDM. None of the clinical and biological parameters was significant between PTDM and control patients. Homozygous carriers of POR*28 or wild-type ABCB1 (rs1045642) gene variants were more frequent in PTDM than in control patients with differences close to significance (p = 0.114 and p = 0.066 respectively). A genetic score based on these variants demonstrated that POR*28/*28 and ABCB1 CC or CT genotype carriers were at a significantly higher risk of developing PTDM after renal transplantation.

CONCLUSION

Identification of PTDM risk factors should allow clinicians to allocate the best immunosuppressant for each patient with renal transplantation, and improve care for patients who are at a higher risk.

[PKHD1 mutations in autosomal recessive polycystic kidney disease (ARPKD): Genotype-phenotype correlations from a series of 308 cases to improve prenatal counselling]

OBJECTIVES

ARPKD is a recessive rare disease due to PKHD1 mutation. The main objective of the study was to characterize the phenotypic variability according to the different types of PKHD1 mutations.

METHODS

This study was performed in 308 ARPKD patients with a genetic diagnosis from our genetic center. Related physicians provided minimal clinical and biological data.

RESULTS

Patients were divided into three genotypic groups: the first group (G1; n=65) consisted of patients with two truncating mutations, the second group (G2; n=117) of patients with one truncating and one non-truncating mutation, and the third group (G3; n=126) of patients with two non-truncating mutations. In the entire cohort, the outcomes consisted of 31% of pregnancy termination, 18% of neonatal deaths and 51% of patient survival after the neonatal period. The proportion of severe ARPKD (pregnancy termination or neonatal death) was significantly greater in G1: 94% versus 47% in G2 and 27% in G3 (P<0.001).

CONCLUSION

The presence of two truncating mutations in PKHD1 is associated with the most severe perinatal phenotype. However, the phenotypic variability observed in the other genotypic groups requires caution for prenatal counseling.

Renal transplantation in children under 3 years of age: Experience from a single-center study

RTx remains challenging in children under 3 years of age. This single-center study reviewed the medical records of children <3 years transplanted since 1987 (N = 32, Group 1). They were matched for donor type and RTx period with children aged 3-13 years (N = 32, Group 2) and 13-18 years (N = 32, Group 3). There were no between-group significant differences regarding distributions of gender, primary renal disease, proportion of dialysis before RTx, and growth (SDS). Compared to Groups 2 and 3, Group 1 had more peritoneal dialyses (P < .001), more EBV mismatches (P = .04), and longer warm ischemia times (P < .001). The risk of graft loss was not significantly different among age groups (hazard ratio, 2.4 in Group 2 and 2.0 in Group 3 vs Group 1; P = .2). Death occurred in four patients (3 in Group 1 and 1 in Group 2) and graft loss occurred in 28 patients, mainly due to chronic allograft nephropathy. In recipients <3 years of age, the outcomes of RTx are close to those obtained in older pediatric age groups. Thus, young patients may be transplanted in experienced multidisciplinary teams without additional risks provided that particular attention is paid to donor selection and prevention/early diagnosis of comorbidities and complications.

Skeletal impairment in Pierson syndrome: Is there a role for lamininβ2 in bone physiology?

INTRODUCTION

Pierson syndrome is caused by a mutation of LAMB2, encoding for laminin β2. Clinical phenotype is variable but usually associates congenital nephrotic syndrome (CNS) and ocular abnormalities. Neuromuscular impairment has also been described.

METHODS

We report on a 15-year old girl, suffering from Pierson Syndrome, who developed severe bone deformations during puberty. This patient initially displayed CNS and microcoria, leading to the clinical diagnosis of Pierson syndrome. Genetic analysis revealed a truncating mutation and a splice site mutation of LAMB2. The patient received a renal transplantation (R-Tx) at the age of 3. After R-Tx, renal evolution was simple, the patient receiving low-dose corticosteroids, tacrolimus and mycophenolate mofetil. At the age of 12, bone deformations progressively appeared. At the time of bone impairment, renal function was subnormal (glomerular filtration rate using iohexol clearance 50mL/min per 1.73m²), and parameters of calcium/phosphate metabolism were normal (calcium 2.45mmol/L, phosphorus 1.30mmol/L, PTH 81ng/L, ALP 334U/L, 25OH-D 73nmol/L). Radiographs showed major deformations such as scoliosis, genu varum and diffuse epiphyseal abnormalities. A high resolution scanner (HR-pQCT) was performed, demonstrating a bone of "normal low" quantity and quality; major radial and cubital deformations were observed. Stainings of laminin β2 were performed on bone and renal samples from the patient and healthy controls: as expected, laminin β2 was expressed in the control kidney but not in the patient's renal tissue, and a similar pattern was observed in bone.

CONCLUSION

This is the first case of skeletal impairment ever described in Pierson syndrome. Integrin α3β1, receptor for laminin β2, are found in podocytes and osteoblasts, and the observation of both the presence of laminin β2 staining in healthy bone and its absence in the patient's bone raises the question of a potential role of laminin β2 in bone physiology.

Bicarbonate buffered peritoneal dialysis fluid upregulates angiopoietin-1 and promotes vessel maturation

Background

Ultrafiltration decline is a progressive issue for patients on chronic peritoneal dialysis (PD) and can be caused by peritoneal angiogenesis induced by PD fluids. A recent pediatric trial suggests better preservation of ultrafiltration with bicarbonate versus lactate buffered fluid; underlying molecular mechanisms are unknown.

Methods

Angiogenic cytokine profile, tube formation capacity and Receptor Tyrosine Kinase translocation were assessed in primary human umbilical vein endothelial cells following incubation with bicarbonate (BPDF) and lactate buffered (LPDF), pH neutral PD fluid with low glucose degradation product content and lactate buffered, acidic PD fluid with high glucose degradation product content (CPDF). Peritoneal biopsies from age-, PD-vintage- and dialytic glucose exposure matched, peritonitis-free children on chronic PD underwent automated histomorphometry and immunohistochemistry.

Results

In endothelial cells angiopoietin-1 mRNA and protein abundance increased 200% upon incubation with BPDF, but decreased by 70% with LPDF as compared to medium control; angiopoietin-2 remained unchanged. Angiopoietin-1/Angiopoietin-2 protein ratio was 15 and 3-fold increased with BPDF compared to LPDF and medium. Time-lapse microscopy with automated network analysis demonstrated less endothelial cell tube formation with BPDF compared to LPDF and CPDF incubation. Receptor Tyrosine Kinase translocated to the cell membrane in BPDF but not in LPDF or CPDF incubated endothelial cells. In children dialyzed with BPDF peritoneal vessels were larger and angiopoietin-1 abundance in CD31 positive endothelium higher compared to children treated with LPDF.

Conclusion

Bicarbonate buffered PD fluid promotes vessel maturation via upregulation of angiopoietin-1 in vitro and in children on dialysis. Our findings suggest a molecular mechanism for the observed superior preservation of ultrafiltration capacity with bicarbonate buffered PD fluid with low glucose degradation product content.

Long-Term Outcome of Steroid-Resistant Nephrotic Syndrome in Children

We investigated the value of genetic, histopathologic, and early treatment response information in prognosing long-term renal outcome in children with primary steroid-resistant nephrotic syndrome. From the PodoNet Registry, we obtained longitudinal clinical information for 1354 patients (disease onset at >3 months and <20 years of age): 612 had documented responsiveness to intensified immunosuppression (IIS), 1155 had kidney biopsy results, and 212 had an established genetic diagnosis. We assessed risk factors for ESRD using multivariate Cox regression models. Complete and partial remission of proteinuria within 12 months of disease onset occurred in 24.5% and 16.5% of children, respectively, with the highest remission rates achieved with calcineurin inhibitor-based protocols. Ten-year ESRD-free survival rates were 43%, 94%, and 72% in children with IIS resistance, complete remission, and partial remission, respectively; 27% in children with a genetic diagnosis; and 79% and 52% in children with histopathologic findings of minimal change glomerulopathy and FSGS, respectively. Five-year ESRD-free survival rate was 21% for diffuse mesangial sclerosis. IIS responsiveness, presence of a genetic diagnosis, and FSGS or diffuse mesangial sclerosis on initial biopsy as well as age, serum albumin concentration, and CKD stage at onset affected ESRD risk. Our findings suggest that responsiveness to initial IIS and detection of a hereditary podocytopathy are prognostic indicators of favorable and poor long-term outcome, respectively, in children with steroid-resistant nephrotic syndrome. Children with multidrug-resistant sporadic disease show better renal survival than those with genetic disease. Furthermore, histopathologic findings may retain prognostic relevance when a genetic diagnosis is established.

Anti-C1q autoantibodies as markers of renal involvement in childhood-onset systemic lupus erythematosus

BACKGROUND

Childhood-onset systemic lupus erythematosus (cSLE) is rare, and considered more severe than its adult-onset counterpart. Lupus nephritis (LN) occurs more frequently in children, accounting for higher long-term morbidity and mortality compared with adults. Thus, reliable biological markers are needed to predict disease course. This study aimed to investigate the capacity of anti-C1q autoantibodies (Abs) to predict renal flare and global disease activity in cSLE patients, and association with disease activity and kidney involvement.

METHODS

Twenty-eight patients with cSLE including 19 patients (68%) with a history of LN were included retrospectively. Anti-C1q Abs were analysed by ELISA at renal flare-up or in the quiescent phase of disease and compared with Farr dsDNA assay.

RESULTS

Thirty-one flares occurred during follow-up: anti-C1q Abs were positive in 26 (84%), strongly associated with active disease status (p < 0.0001), and correlated with global disease activity score (p < 0.0001) and anti-dsDNA Abs presence (p < 0.0001). The specificity of anti-C1q Abs was higher than anti-dsDNA (73% vs 19%) in discriminating LN patients, whereas the receiver operating characteristic curves were not statistically different (0.83 ± 0.06 vs 0.78 ± 0.08 respectively), similar to C3 dosage. The presence of anti-C1q Abs at diagnosis was not predictive for global or renal flare. Introduction of a modified SLEDAI score excluding dsDNA Abs, demonstrated a stronger correlation of anti-C1q Abs titres with SLEDAI score in comparison with the Farr test.

CONCLUSION

Anti-C1q Abs seem very specific to flares, including LN in children, and their role in daily practice compared with the Farr dsDNA assay needs to be defined.

Effect of center practices on the choice of the first dialysis modality for children and young adults

BACKGROUND

Peritoneal dialysis (PD) remains the modality of choice in children, but there is no clear evidence to support a better outcome in children treated with PD. We aimed to assess factors that have an impact on the choice of dialysis modality in children and young adults in France and sought to determine the roles of medical factors and center practices.

METHODS

We included all patients aged <20 years at the start of renal replacement therapy (RRT), recorded in the French RRT Registry between 2002 and 2013. Hierarchical logistic regression models were used to study the association between the patient/center characteristics and the probability of receiving PD as the first dialysis modality.

RESULTS

We included 806 patients starting RRT in 177 centers, 23 of which were specialized pediatric centers. Six hundred and one patients (74.6 %) started with hemodialysis (HD), whereas 205 (25.4 %) started with PD. A greater probability of PD was found in younger children, whereas starting the treatment in an emergency setting was associated with a low use of PD. We found a significant variability among centers that accounted for 43 % of the total variability. The probability of PD was higher in adult centers and was proportional to the rate of PD in the center.

CONCLUSIONS

Center practices are a major factor in the choice of dialysis modality. This raises concerns about patient and family choices and to what extent doctors may influence the final decision. Further pediatric studies focusing on children's and parents' wishes are needed to provide care as close as possible to patients' and families' expectations.

Cardiovascular Phenotypes in Children with CKD: The 4C Study

BACKGROUND AND OBJECTIVES

Cardiovascular disease is the most important comorbidity affecting long-term survival in children with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Cardiovascular Comorbidity in Children with CKD Study is a multicenter, prospective, observational study in children ages 6-17 years old with initial GFR of 10-60 ml/min per 1.73 m2. The cardiovascular status is monitored annually, and subclinical cardiovascular disease is assessed by noninvasive measurements of surrogate markers, including the left ventricular mass index, carotid intima-media thickness, and central pulse wave velocity. We here report baseline data at study entry and an explorative analysis of variables associated with surrogate markers.

RESULTS

A total of 737 patients were screened from October of 2009 to August of 2011 in 55 centers in 12 European countries, and baseline data were analyzed in 688 patients. Sixty-four percent had congenital anomalies of the kidney and urinary tract; 26.1% of children had uncontrolled hypertension (24-hour ambulatory BP monitoring; n=545), and the prevalence increased from 24.4% in CKD stage 3 to 47.4% in CKD stage 5. The prevalence of left ventricular hypertrophy was higher with each CKD stage, from 10.6% in CKD stage 3a to 48% in CKD stage 5. Carotid intima-media thickness was elevated in 41.6%, with only 10.8% of patients displaying measurements below the 50th percentile. Pulse wave velocity was increased in 20.1%. The office systolic BP SD score was the single independent factor significantly associated with all surrogate markers of cardiovascular disease. The intermediate end point score (derived from the number of surrogate marker measurements >95th percentile) was independently associated with a diagnosis of congenital anomalies of the kidney and urinary tract, time since diagnosis of CKD, body mass index, office systolic BP, serum phosphorus, and the hemoglobin level.

CONCLUSIONS

The baseline data of this large pediatric cohort show that surrogate markers for cardiovascular disease are closely associated with systolic hypertension and stage of CKD.

The Roche Total Mycophenolic Acid® assay: An application protocol for the ABX Pentra 400 analyzer and comparison with LC-MS in children with idiopathic nephrotic syndrome

Background

For TDM of mycophenolate acid (MPA), the Roche Total Mycophenolic Acid® assay based on the inhibition of recombinant inosine monophosphate dehydrogenase (IMPDH) has been shown to be a simple and reliable alternative to chromatographic methods. We have adapted this assay on the ABX Pentra 400 analyzer (HORIBA).

Objective

To investigate the analytical performances of the Roche Total Mycophenolic Acid® assay on the ABX Pentra 400 and to compare it to an LC-MS method using samples from children with nephrotic syndrome treated with mycophenolate mofetil (MMF).

Material and methods

Configuration of the open-channel on the ABX Pentra 400 was based on the Roche MPA assay package insert. Precision was determined as described in the CLSI protocol EP5-A2. Comparison with the LC-MS method was performed using 356 plasma samples from 42 children with nephrotic syndrome (8 h pharmacokinetic profiles).

Results

The enzymatic assay demonstrated high precision. The %CV for Within Run Imprecision ranged from 5.5% at 1.2 mg/L to 1.5% at 14.1 mg/L and Total Imprecision ranged from 9.3% to 2.5%. The method comparison with plasma samples from children yielded overall a good correlation and a good agreement between both methods. The Passing Bablok regression analysis showed the following results: [Roche MPA assay]=1.058 [MPA LC-MS] −0.06; rho=0.996.

Conclusion

The Roche Total Mycophenolic Acid® assay is adaptable to the ABX Pentra 400 analyzer, and demonstrates accurate and precise measurement of MPA in plasma obtained from children with nephrotic syndrome.

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Adaptation of the Roche Total Mycophenolic Acid® assay to the Pentra 400 analyzer.

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Comparison with LC-MS in children with idiopathic nephrotic syndrome.

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Therapeutic drug monitoring of mycophenolate mofetil.