Marcin Tkaczyk

Genetic screening in adolescents with steroid-resistant nephrotic syndrome

Genetic screening paradigms for congenital and infantile nephrotic syndrome are well established; however, screening in adolescents has received only minor attention. To help rectify this, we analyzed an unselected adolescent cohort of the international PodoNet registry to develop a rational screening approach based on 227 patients with nonsyndromic steroid-resistant nephrotic syndrome aged 10-20 years. Of these, 21% had a positive family history. Autosomal dominant cases were screened for WT1, TRPC6, ACTN4, and INF2 mutations. All other patients had the NPHS2 gene screened, and WT1 was tested in sporadic cases. In addition, 40 sporadic cases had the entire coding region of INF2 tested. Of the autosomal recessive and the sporadic cases, 13 and 6%, respectively, were found to have podocin-associated nephrotic syndrome, and 56% of them were compound heterozygous for the nonneutral p.R229Q polymorphism. Four percent of the sporadic and 10% of the autosomal dominant cases had a mutation in WT1. Pathogenic INF2 mutations were found in 20% of the dominant but none of the sporadic cases. In a large cohort of adolescents including both familial and sporadic disease, NPHS2 mutations explained about 7% and WT1 4% of cases, whereas INF2 proved relevant only in autosomal dominant familial disease. Thus, screening of the entire coding sequence of NPHS2 and exons 8-9 of WT1 appears to be the most rational and cost-effective screening approach in sporadic juvenile steroid-resistant nephrotic syndrome.

Increased cystatin C concentration in urine of nephrotic children

The aim of this study was to evaluate changes in urine and plasma concentrations of cystatin C in children with a relapse of the idiopathic nephrotic syndrome (INS). The study group comprised 12 children with INS with proteinuria and 12 children in an 8-week remission, both treated with steroids. Twelve healthy children served as controls. Cystatin C was detectable in the urine of children with proteinuria. The study suggests that massive proteinuria may influence renal cystatin C handling.

Markers of Endothelial Dysfunction in Children with Idiopathic Nephrotic Syndrome

Endothelial function impairment may constitute a link between nephrotic syndrome and atherosclerosis. We assessed changes in plasma thrombomodulin, von Willebrand factor and plasminogen activator inhibitor-1 at different stages of idiopathic nephrotic syndrome in children and correlated them with clinical and biochemical parameters. The study group included 132 nephrotic children (aged 2–18 years) divided into four groups, i.e. in acute phase of the disease with proteinuria, during steroid-induced remission, steroid-free remission, and in long-term, steroid-free remission. Forty-one healthy children served as controls. Plasma thrombomodulin, plasminogen activator inhibitor-1 and von Willebrand factor activity were increased in children with early nephrotic relapse. They systematically decreased in later stages of the disease but the increase in von Willebrand factor persisted in drug-free remission. These disturbances were dependent on the degree of proteinuria and serum albumin concentration. The study revealed that nephrotic children show markers of endothelial dysfunction that are dependent on the disease activity. This leads to the hypothesis that children with severe clinical course of nephrotic syndrome may be at high risk of accelerated atherogenesis.

Perception of health-related quality of life in children with chronic kidney disease by the patients and their caregivers: Multicentre national study results

ObjectiveThe aim of the study was to analyse the health-related quality of life (HRQoL) in Polish children with chronic kidney disease (CKD) dependant on the CKD stage, treatment modality and selected social life elements in families of the patients. Furthermore, potential differences between self-report and parent/proxy reports and the factors influencing them were assessed.MethodsA total of 203 CKD children (on haemodialysis (HD), peritoneal dialysis (PD) and conservative treatment (CT)) and their 388 parent/proxies were enrolled into a cross-sectional national study. The demographic and social data were evaluated. We used the Paediatric Quality of Life Inventory 4.0 Generic Core Scales to assess the HRQoL in children.ResultsHealth-related quality of life scores for all CKD groups were significantly lower in all domains compared with population norms, the lowest one being in the HD group. In CT children, HRQoL did not depend on the CKD stage. Both parents assessed the HRQoL of their children differently depending on their involvement in the care. There are differences between the HRQoL scores of the children and their parents.ConclusionThe HRQoL in children with CKD is lower than in healthy children. This is already observed in the early stages of the disease. The disease itself influences the child’s mental state. Children on HD require special support on account of the lowest demonstrated overall HRQoL. Children’s lower rating of the quality of life observed by their parents may render the patients unmotivated and adversely affect their adjustment to life in later years. It may also create conflicts between the parents and the children.

Anxiety in Children and Adolescents with Chronic Kidney Disease - Multicenter National Study Results

Background/Aims: Chronic medical illness is a significant risk factor for the development of psychiatric disorders. The aims of the study were: to investigate the level of anxiety in children with chronic kidney disease (CKD) and to identify factors associated with the presence of that emotional problem. Methods: CKD children on hemodialysis (HD, n=22), peritoneal dialysis (PD, n=20,) and on conservative treatment (CT, n=95) were enrolled in the study. We used State-Trait Anxiety Inventory (STAI) for adolescents and STAI-C for children. Socio-demographic and physical factors were assessed. Results: There was a significantly higher level of anxiety-state among HD children (8-12 years) compared with other groups of participants of the same age and Polish population norms. The level of anxiety among adolescents (13-18 years), both anxiety-state and anxiety-trait, was significantly higher in the HD group compared with other groups, which did not differ among themselves. In the HD adolescents, there was a correlation between the anxiety-state and the duration of the disease as well as with the number of hospitalizations. PD adolescents in the mainstream education had higher levels of anxiety-state and anxiety-trait compared with home schooled patients. Conclusions: Even though children and adolescents with CKD are at risk of developing a variety of emotional disorders, the level of anxiety among the researched group, with the exception of HD patients, was not significantly different than the level of anxiety among healthy subjects. Adolescents on HD who present a high level of anxiety should undergo long-term psychological treatment.

Retrospective cohort study of familial hypomagnesaemia with hypercalciuria and nephrocalcinosis due to CLDN16 mutations

BACKGROUND Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare autosomal recessive tubular disorder exhibiting a high risk for progressive chronic kidney disease (CKD). METHODS This is a retrospective multicentre study of 25 paediatric cases with FHHNC in Poland. Median age at diagnosis was 4 years and median follow-up time was 4.8 years. RESULTS All cases of FHHNC carried recessive mutations in CLDN16. The founder mutation in CLDN16, Leu151Phe, was the most frequent cause of FHHNC in Polish patients, with 13 (52%) cases being homozygous and 5 (20%) carrying Leu151Phe allele in compound heterozygosity. All cases showed nephrocalcinosis, increased urinary fractional excretion of magnesium and hypercalciuria. Other disease features included hypomagnesaemia (76%), hyperparathyroidism (76%), hyperuricaemia (56%) and hypocitraturia (60%). Treatment with thiazides effectively reduced hypercalciuria in most cases. During follow-up, renal function declined in 60% of patients; 12% of patients reached CKD stage 3 or 4 and one patient developed end-stage renal failure. CONCLUSIONS We report one of the largest cohorts of FHHNC cases caused by CLDN16 mutations. A missense variant of CLDN16, Leu151Phe, is the most common mutation responsible for FHHNC in Poland. Additionally, we found that normomagnesaemia does not exclude FHHNC and the calculation of fractional excretion of Mg can be diagnostic in the setting of normomagnesaemia. We also demonstrate the efficacy of a treatment with thiazides in terms of hypercalciuria in the majority of patients.

Ectopic mediastinal parathyroid carcinoma as a cause of dialysis-dependent renal failure

Carcinoma of the parathyroid gland is infrequent in patients with secondary hyperparathyroidism. Typical clinical symptoms are related to the presence of a neck mass and hypercalcemia. We describe a case of a 55‐year‐old man in whom primary parathyroid carcinoma led most likely to the development of end‐stage dialysis‐dependent renal failure, and the diagnosis of the cancer was delayed due to ectopic localization of the tumor, and dramatic complications in the clinical course of the disease, including acute pancreatitis and peritionitis. However, 6 months after successful surgery and subsequent radiotherapy, the patient is well and free from recurrences but remains chronically dialysis‐dependent.

Acute kidney injury in a single pediatric intensive care unit in Poland: a retrospective study.

Background/Aims: The recent improvements of management of patients in pediatric intensive care units (PICU) are associated with improved outcome. However, this decrease in mortality is associated with an increased number of children with acute kidney injury (AKI), especially in patients with multiorgan failure. Methods: The report presents a retrospective analysis of 25 cases of AKI (assessed based on the pRIFLE criteria) in PICU within 7 years. Results: AKI was diagnosed in 1.24% of all hospitalized children. AKI percentage duration (as compared to the total hospitalization time) in the children who died vs. the survivors was 79.55% vs. 46.19%, respectively (p<0.05). The mortality rate of AKI patients was 40% which was 4.4-times higher as compared to the total mortality rate in PICU. The final cumulative survival ratio (FCSR) of patients meeting the oliguria criterion (which was met in 48% of AKI patients) was 37% vs. 49% in non-oliguric children. Averaged urine output values in the first week of hospitalization in the deceased vs. survivors were 1.49 vs. 2.57 ml/kg/h, respectively (p<0.05). Conclusions: Oliguria should not be considered as a sensitive parameter for AKI diagnosing in children below one year of age. A decreased mean urine output in the first week of PICU hospitalization (less than 1.4 ml/kg/h) should be considered as a poor prognostic factor. In many cases AKI was diagnosed too infrequently and too late.

Anaemia treatment in chronically dialysed children: a multicentre nationwide observational study

Abstract Objective.Erythropoiesis-stimulating agents (ESAs) are applied as a standard therapy in children with anaemia in chronic kidney disease. The aim of this study was to describe the efficacy and details of ESA treatment in a population of dialysed children in Poland. Material and methods. The study had a prospective observational design and was performed in 12 dialysis centres. The study group comprised 117 dialysed children with a mean age at enrolment of 165.33 (97.18–196.45) months. Results.Dialysed children were treated mostly with epoietin beta and darbepoietin. The mean dose of ESA was 99 (68–147) U/kg/week with a significant difference between patients on peritoneal dialysis [83 (54–115)] and haemodialysis [134 (103–186)] (p < 0.0001). The mean haemoglobin of all the time-point tests during 6 months was 10.91 ± 1.18 g/dl. The efficacy of anaemia treatment was unsatisfactory in 52% of subjects. In multivariate analysis, initial haemoglobin level <10 g/l, any infection, younger age at first dialysis, malnutrition and inadequate ESA dosage remained significant predictors of anaemia. Conclusions.The study revealed that anaemia treatment in Polish children is unsatisfactory. Late commencement of the treatment, inadequate dosing, malnutrition and infections could constitute risk factors for therapy failure.

Effect of hypertension and antihypertensive medications on residual renal function in children treated with chronic peritoneal dialysis

PURPOSE To evaluate the effect of hypertension (HTN) and antihypertensive medications (AHM) on residual renal function (RRF) in children on CAPD and APD. MATERIAL/METHODS We retrospectively evaluated underlying kidney disease, systolic and diastolic blood pressure (SBP/DBP), presence and control of HTN (SBP/DBP≥95th percentile), AHM, RRF (daily diuresis, residual glomerular filtration rate [rGFR]), biochemical parameters, BMI Z-score, and dialysis parameters during 12-month follow-up in 87 children (38 CAPD, 49 APD) aged 10.22±4.31 years. The rate of RRF loss was expressed as absolute and relative [%] reduction. RESULTS At baseline, HTN was found in 74.7% patients (CAPD/APD: 84.2%/67.3%, P=0.06), most commonly in HUS and least frequently in CAKUT. The proportion of CAPD/APD patients with poorly controlled HTN was 70.0%/63.3% (P=0.50). Relative daily diuresis loss in children with uncontrolled HTN was higher (P=0.017) compared to children with SBP/DBP <95th percentile. No effect of AHM on the rate of RRF loss was found. In multivariate analysis, absolute daily diuresis loss was related to baseline diuresis (β=-0.30, P<0.001) and proteinuria (β=-0.31, P=0.004); absolute rGFR loss to baseline rGFR (β=-0.73, P<0.001) and glucose load after 12 months (β=-0.36, P=0.02); relative daily diuresis loss to mean BMI Z-score (β=-0.44, P=0.04); and relative rGFR to baseline rGFR (β=-0.37, P<0.001) and SBP percentile (β=-0.21, P=0.045).