Abstract
Distal renal tubular acidosis (dRTA) is characterized by an impaired ability of the distal tubule to excrete acid, leading to metabolic acidosis. Associated complications include bone ...disease, growth failure, urolithiasis and hypokalaemia. Due to its rarity, there is limited evidence to guide diagnosis and management; however, available data strongly suggest that metabolic control of the acidosis by alkali supplementation can halt or revert almost all complications. Despite this, cohort studies show that adequate metabolic control is present in only about half of patients, highlighting problems with treatment provision or adherence. With these clinical practice points the authors, part of the working groups tubulopathies in the European Rare Kidney Disease Reference network and inherited kidney diseases of the European Society for Paediatric Nephrology, aim to provide guidance for the management of patients with dRTA to facilitate adequate treatment and establish an initial best practice standard against which treatment of patients can be audited.
Background
The need for dialysis after kidney allograft failure (DAGF) is among the top five reasons for dialysis initiation, making this an important topic in clinical nephrology. However, data are ...scarce on dialysis choice after transplantation and clinical outcomes for DAGF in children.
Methods
Patients receiving chronic dialysis < 18 years were recorded from January 1991 to January 2019 by the Italian Registry of Pediatric Chronic Dialysis (IRPCD). We investigated factors influencing choice of dialysis modality, patient outcome in terms of mortality, switching dialysis modality, and kidney transplantation.
Results
Among 118 patients receiving DAGF, 41 (35%) were treated with peritoneal dialysis (PD), and 77 (65%) with haemodialysis (HD). Significant predictors for treatment with PD were younger age at dialysis start (OR 0.85 per year increase 95%CI 0.72–1.00) and PD use before kidney transplantation (OR 8.20 95%CI 1.82–37.01). Patients entering DAGF in more recent eras (OR 0.87 per year increase 95%CI 0.80–0.94) and with more than one dialysis modality before kidney transplantation (OR 0.56 for being treated with PD 0.12–2.59) were more likely to be initiated on HD. As compared to patients on HD, those treated with PD exhibited increased but non-significant mortality risk (HR 2.15 95%CI 0.54–8.6; p = 0.28) and higher prevalence of dialysis-related complications during DAGF (p = 0.002)
Conclusions
Patients entering DAGF in more recent years are more likely to be initiated on HD. In this specific population of children, use of PD seems associated with a more complicated course.
Graphical abstract
A higher resolution version of the Graphical abstract is available as Supplementary information
To study the predictive value of biopsy lesions in IgA nephropathy in a range of patient ages we retrospectively analyzed the cohort that was used to derive a new classification system for IgA ...nephropathy. A total of 206 adults and 59 children with proteinuria over 0.5 g/24 h/1.73 m2 and an eGFR of stage-3 or better were followed for a median of 69 months. At the time of biopsy, compared with adults children had a more frequent history of macroscopic hematuria, lower adjusted blood pressure, and higher eGFR but similar proteinuria. Although their outcome was similar to that of adults, children had received more immunosuppressants and achieved a lower follow-up proteinuria. Renal biopsies were scored for variables identified by an iterative process as reproducible and independent of other lesions. Compared with adults, children had significantly more mesangial and endocapillary hypercellularity, and less segmental glomerulosclerosis and tubulointerstitial damage, the four variables previously identified to predict outcome independent of clinical assessment. Despite these differences, our study found that the cross-sectional correlation between pathology and proteinuria was similar in adults and children. The predictive value of each specific lesion on the rate of decline of renal function or renal survival in IgA nephropathy was not different between children and adults.
We assessed the activation of the oxidative stress pathway in patients with IgA nephropathy (IgAN), while evaluating the classic marker of the disease (galactose-deficient serum IgA1).
Sera from 292 ...patients and 69 healthy controls from Italy and the United States were assayed for advanced oxidation protein products (AOPPs), free sulfhydryl groups on albumin (SH-Alb), and IgA1 with galactose-deficient hinge-region O-glycans (Gd-IgA1). Gd-IgA1 was detected by binding to Helix aspersa agglutinin (HAA) and expressed as total Gd-IgA1 or as degree of galactose deficiency relative to a standard Gd-IgA1 myeloma protein (%HAA).
Sera from IgAN patients showed higher levels of Gd-IgA1, %HAA, and AOPPs, but lower levels of SH-Alb in comparison to that from healthy controls. Serum levels of AOPPs significantly correlated with serum Gd-IgA1 and %HAA. The relationship between these biomarkers and clinical features at sampling and during follow-up was assessed in 62 patients with long-term follow-up. AOPPs and %HAA correlated with proteinuria at sampling and independently associated with subsequent proteinuria. Levels of AOPPs correlated with rate of decline in renal function after sampling. The combination of a high level of AOPPs and a high level of %HAA associated with decline in estimated GFR.
Serum levels of aberrantly glycosylated IgA1 are elevated and oxidative stress pathways are activated in patients with IgAN; the intensity of the stress correlated with expression and progression of the disease. We speculate that oxidative stress may modulate the nephrotoxicity of aberrantly glycosylated IgA1 in IgAN.
Inherited kidney diseases are among the leading causes of kidney failure in children, resulting in increased mortality, high healthcare costs and need for organ transplantation. Next-generation ...sequencing technologies can help in the diagnosis of rare monogenic conditions, allowing for optimized medical management and therapeutic choices.
Clinical exome sequencing (CES) was performed on a cohort of 191 pediatric patients from a single institution, followed by Sanger sequencing to confirm identified variants and for family segregation studies.
All patients had a clinical diagnosis of kidney disease: the main disease categories were glomerular diseases (32.5%), ciliopathies (20.4%), CAKUT (17.8%), nephrolithiasis (11.5%) and tubular disease (10.5%). 7.3% of patients presented with other conditions. A conclusive genetic test, based on CES and Sanger validation, was obtained in 37.1% of patients. The highest detection rate was obtained for ciliopathies (74.4%), followed by nephrolithiasis (45.5%), tubular diseases (45%), while most glomerular diseases and CAKUT remained undiagnosed.
Results indicate that genetic testing consistently used in the diagnostic workflow of children with chronic kidney disease can (i) confirm clinical diagnosis, (ii) provide early diagnosis in the case of inherited conditions, (iii) find the genetic cause of previously unrecognized diseases and (iv) tailor transplantation programs.
Familial hyperaldosteronism (FH) encompasses 3 types of autosomal dominant hyperaldosteronisms leading to inheritable hypertension. FH type II (FH-II), undistinguishable from sporadic ...hyperaldosteronism, represents the most frequent cause of inheritable hypertension and is believed to only manifest in adults. FH-III is a severe variety of PA resistant to pharmacotherapy and recently demonstrated to be caused by mutations in the gene encoding the potassium channel KCNJ5. In this report, we describe a FH pediatric patient, remarkable both for age at onset and unusual presentation: a two-years old girl with polyuric-polydipsic syndrome and severe hypertension, successfully treated with canrenone and amiloride. The girl had severe hypertension, hypokalemia, hypercalciuria, suppressed renin activity, high aldosterone, and unremarkable adrenal imaging. FH type I was ruled out by glucocorticoid suppression test, PCR test for CYP11B1/CYP11B2 gene, and urinary 18-oxo-cortisol and 18-hydroxy-cortisol excretion, which was in FH-II range. In spite of a clear-cut FH-II phenotype, the girl and her mother were found to harbor a FH-III genotype with KCNJ5 mutation (c.452G>A). Treatment with canrenone was started, resulting in prompt normalization of electrolytes and remission of polyuric-polydypsic syndrome. The addition of amiloride led to a complete normalization of blood pressure. This report expands the phenotypic spectrum of FH-III to a milder end, mimiking FH-II phenotype demonstrating that pharmacotherapy may be effective. This also implies that FH-II/III should be considered in the differential diagnosis of hypertensive children and, perhaps, that the offspring of patients with hyperaldosteronism should be screened for hypertension.
Oxidative stress pathways are activated in diabetes, particularly when dialysis is required (DD). NF-kB is activated in this clinical condition. Since N-Acetyl-cysteine (NAC) is an anti-oxidant, we ...aimed at investigating its effect in modulating NF-kB activation in lymphomonocytes (PBMC) of DD patients.
Twenty-five DD patients were enrolled in a cross-over designed study. Tests were performed at T0 and after one month (T1) of treatment with NAC and three months after NAC withdrawal. We assessed NF-kB activation by EMSA, levels of advanced oxidation protein products (AOPP) by spectral analysis, total antioxidant capacity (TAC) by colorimetry, and apoptosis by FACS.
At T0 a statistically significant increased activation of the subunits of NF-kB, p50/p65, was detected in PBMC of DD patients in comparison to controls (both P<.0001). After one month of NAC both p50-p50/p50-p65 dimers were significantly reduced (P<.004 and .006). Three months after drug withdrawal NF-kB increased again to basal levels (P<.002 and P<.001 vs. end of treatment with NAC). AOPP and TAC levels and the percentage of apoptotic PBMC revealed modifications in accordance with NFkB activation. In a multivariate linear regression model using delta AOPP as the dependent variable and delta p50-p50, delta TAC, and delta APO as independent variables, we found that all three dependent parameters all retained an independent correlation with delta AOPP.
Our data indicate in vivo a modulation by NAC of parameters indicating a redox imbalance in DD patients on hemodialysis. The use of NAC might suggest a potential clinical benefit.
The benefits of tonsillectomy in IgA nephropathy (IgAN) are still debated. Tonsillectomy may remove pathogen sources and reduce the mucosal associated lymphoid tissue (MALT), limiting ...degalactosylated IgA1 (deGal-IgA1) production, which is considered to be the initiating pathogenetic event leading to IgA glomerular deposition. In the European network VALIGA, 62/1147 IgAN patients underwent tonsillectomy (TxIgAN). In a cross-sectional study 15 of these patients were tested and compared to 45 non-tonsillectomized IgAN (no-TxIgAN) and healthy controls (HC) regarding levels of deGal-IgA1, and markers of innate immunity and oxidative stress, including toll-like receptors (TLR)2, 3, 4 and 9 mRNAs, proteasome (PS) and immunoproteasome (iPS) mRNAs in peripheral blood mononuclear cells (PBMC), and advanced oxidation protein products (AOPP). Levels of deGal-IgA1 were lower in TxIgAN than in no-TxIgAN (p = 0.015), but higher than in HC (p = 0.003). TLR mRNAs were more expressed in TxIgAN than in HC (TLR4, p = 0.021; TLR9, p = 0.027), and higher in TxIgAN than in no-TxIgAN (p ≤ 0.001 for TLR2, 4, 9). A switch from PS to iPS was detected in PBMC of TxIgAN in comparison to HC and it was higher than in no-TxIgAN large multifunctional peptidase (LMP)2/β1, p = 0.039; LPM7/β5, p < 0.0001. The levels of AOPP were significantly higher in TxIgAN than HC (p < 0.001) and no-TxIgAN (p = 0.033). In conclusion, the activation of innate immunity via TLRs and ubiquitin–proteasome pathways and the pro-oxidative milieu were not affected by tonsillectomy, even though the levels of aberrantly galactosylated IgA1 were lower in patients with IgAN who had tonsillectomy. The residual hyperactivation of innate immunity in tonsillectomized patients may result from extra-tonsillar MALT.
Reliable biomarkers are needed to identify patients with glomerular disease at risk of progression. Transforming growth factor beta 1 (TGF-β1) and monocyte chemotactic protein 1 (MCP-1) play key ...roles in promoting renal tissue injury. Whether their urinary measurement adds value to current predictors of progression is uncertain.
We enrolled patients with diabetic (n=53) and nondiabetic (n=47) proteinuric renal disease and retrospectively studied their rate of renal function decline over a defined period of 2 years. We simultaneously measured urinary protein, MCP-1 and TGF-β1, standardized to urinary creatinine.
The initial estimated glomerular filtration rate, proteinuria and rate of renal function decline (slope) were 36 ml/min per 1.73 m2, 1.1 g/day and -4.0 ± 7.2 ml/ min per 1.73 m2 year. Median urinary TGF-β1 and MCP- 1 levels were 0.3 (range 0.0-28.1) and 18 (range 3-370) ng/mmol of creatinine, respectively. Urinary protein and MCP-1 to creatinine ratios were associated with slope, and this applied to both diabetic and nondiabetic patients separately. Urinary TGF-β1 showed no relation to slope. However, the majority of its measurements were below the suggested reproducibility threshold. Using linear regression, both normalized urinary protein and MCP-1 were independently associated with the slope. Adding urinary MCP-1 to the model statistically raised the adjusted R2 from 0.35 to 0.40, refining patient risk stratification. Using cutoffs for urinary protein and MCP-1 obtained by receiver operating characteristic curves, the risk of progression was confidently determined in 80% of patients.
Urinary MCP-1 is a marker of renal function decline in diabetic and nondiabetic proteinuric renal disease, independent of and additive to proteinuria.
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