Steroid-sparing therapies are often used to prolong disease remission while minimizing steroid toxicity in childhood steroid-sensitive nephrotic syndrome (SSNS). This study aims to describe practice variation in the use of steroid-sparing medications for childhood SSNS in Canada. Children (1–18 years) with nephrotic syndrome (NS) from eleven pediatric nephrology centers in Canada were enrolled in the Canadian Childhood Nephrotic Syndrome (CHILDNEPH) prospective cohort from 2013–2019. Data, including time to first relapse for children treated with cyclophosphamide, tacrolimus, mycophenolate mofetil, cyclosporine and rituximab were analyzed using summary statistics. Participants who received steroid-sparing therapies prior to enrolment were excluded. Of the 371 children enrolled, 321 (86.5

Abstract Background In this longitudinal cohort study, we aimed to determine the association between average daily corticosteroid dose and time to first relapse among children with first presentation of nephrotic syndrome. Method We enrolled children (1–18 years) with nephrotic syndrome at the time of first presentation of nephrotic syndrome across 11 Canadian centers in the CHILDNEPH study between 2013–2019. Exposure was within-person average daily corticosteroid dose. Primary outcome was time to first relapse after entry into the study. Cox proportional hazards regression models were created to estimate the risk of relapse after adjusting for potential confounders. Results Among 328 children (129 females) with median age 4.3 (IQR 3.6) years, the unadjusted median time to first relapse in the study was 128 (42–707) days. The relationship between average daily corticosteroid dose and time to relapse was modified by age (HR: 0.87, 95% CI 0.82–0.93) with younger children having a higher risk of relapse compared to older children for the same corticosteroid dose. Relationships between time to first relapse, average corticosteroid dose, and age remained unchanged when including those children who entered the study at first or second relapse or those who relapsed while tapering the prednisone during the episode at entry in the study. Conclusion Younger children, despite receiving same average daily corticosteroid dose, experience faster time to relapse compared to older children. Further study is warranted to examine the optimal dosing of corticosteroids by age of the child.

Nephromegaly in childhood can result from a wide variety of causes, yet iron-deficiency anemia has not been previously described. We report a child with severe iron-deficiency anemia associated with transient bilateral nephromegaly. We hypothesize that increased renal production of erythropoietin as well as greater cardiac output with subsequent glomerular hyperfiltration secondary to critical anemia explained the observed nephromegaly. The normalization of kidney size following resolution of anemia supports this hypothesis. Our case report suggests an additional etiology of bilateral nephromegaly in the pediatric population and thus merits attention among physicians.

IgA nephropathy (IgAN) and Henoch-Schönlein purpura are common glomerular disorders in children sharing the same histopathologic pattern of IgA deposits within the mesangium, even if their physiopathology may be different. Repeated exposure to pathogens induces the production of abnormal IgA1. The immune complex deposition in the renal mesangium in IgAN or potentially in small vessels in Henoch-Schönlein purpura induces complement activation via the alternative and lectin pathways. Recent studies suggest that levels of membrane attack complex (MAC) in the urine might be a useful indicator of renal injury. Because of the emerging availability of therapies that selectively block complement activation, the aim of the present study is to investigate whether MAC immunostaining might be a useful marker of IgA-mediated renal injury. We conducted immunohistochemistry analysis of the MAC on renal biopsies from 67 pediatric patients with IgAN and Henoch-Schönlein purpura. We classified their renal biopsies according to the Oxford classification, retrieved symptoms, biological parameters, treatment, and follow-up. We found MAC expression was significantly related to impaired renal function and patients whose clinical course required therapy. MAC deposits tend to be more abundant in patients with decreased glomerular filtration rate (p = 0.02), patients with proteinuria > 0.750 g/day/1.73 m2, and with nephrotic syndrome. No correlation with histological alterations was observed. We conclude that MAC deposition could be a useful additional indicator of renal injury in patients with IgAN and Henoch-Schönlein purpura, independent of other indicators.

Hypertension Canada's 2020 guidelines for the prevention, diagnosis, risk assessment, and treatment of hypertension in adults and children provide comprehensive, evidence-based guidance for health care professionals and patients. Hypertension Canada develops the guidelines using rigourous methodology, carefully mitigating the risk of bias in our process. All draft recommendations undergo critical review by expert methodologists without conflict to ensure quality. Our guideline panel is diverse, including multiple health professional groups (nurses, pharmacy, academics, and physicians), and worked in concert with experts in primary care and implementation to ensure optimal usability. The 2020 guidelines include new guidance on the management of resistant hypertension and the management of hypertension in women planning pregnancy.

Hypertension Canada provides annually updated, evidence-based guidelines for the diagnosis, assessment, prevention, and treatment of hypertension in adults and children. This year, the adult and pediatric guidelines are combined in one document. The new 2018 pregnancy-specific hypertension guidelines are published separately. For 2018, 5 new guidelines are introduced, and 1 existing guideline on the blood pressure thresholds and targets in the setting of thrombolysis for acute ischemic stroke is revised. The use of validated wrist devices for the estimation of blood pressure in individuals with large arm circumference is now included. Guidance is provided for the follow-up measurements of blood pressure, with the use of standardized methods and electronic (oscillometric) upper arm devices in individuals with hypertension, and either ambulatory blood pressure monitoring or home blood pressure monitoring in individuals with white coat effect. We specify that all individuals with hypertension should have an assessment of global cardiovascular risk to promote health behaviours that lower blood pressure. Finally, an angiotensin receptor-neprilysin inhibitor combination should be used in place of either an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in individuals with heart failure (with ejection fraction < 40%) who are symptomatic despite appropriate doses of guidelinedirected heart failure therapies. The specific evidence and rationale underlying each of these guidelines are discussed.

Background: We report on the proceedings of a national workshop held in Canada with the aims to identify priorities for research in childhood nephrotic syndrome and to develop a national strategy to address these priorities. Methods: A diverse group of participants attended the meeting, including patients, family members, researchers, and health care providers. We used small group discussions to explore priorities as perceived by patients and families and by health care providers and researchers. Results: Research evaluating glucocorticoid minimization or glucocorticoid-sparing regimens was a consistent theme in the patient and family discussion group. Families also indicated the need for precise prognostic information at diagnosis, more information to help them choose the best available therapy, and more resources for disease management. Health care providers emphasized the importance of better disease characterization including genotyping and phenotyping patients, better understanding the pathogenesis, and the need of providing targeted therapy and precise prognostic information. Conclusions: These priorities will inform the development and future directions of the Canadian Childhood Nephrotic Syndrome (CHILDNEPH) project, a national research initiative to improve care and outcomes of patients with childhood onset nephrotic syndrome.

Background/Aims: Glucose-galactose malabsorption (GGM) is a rare and potentially fatal disorder. The autosomal recessive mutation of the SGLT1 gene interferes with the active glucose transport in the gut resulting in osmotic diarrhea and failure to thrive (FTT). Two nonrelated infants with GGM are presented as well as a novel mutation in SGLT1. Case Presentation: The first case consulted for FTT and presented with hypercalcemia and hypercalciuria. His mother had self-medicated with high doses of vitamin D. The second case consulted for macroscopic hematuria, and presented with dehydration and secondary acute kidney injury. In both cases, the profuse diarrhea, initially mistaken for polyuria, promptly resolved after the introduction of glucose-galactose-free milk. Investigations showed bilateral nephrocalcinosis and high levels of 1,25(OH)2D3 in both patients. We hypothesize that the upregulation of epithelial calcium channels (TRPV6) and 1,25(OH)2D3 are possible factors involved in the pathophysiology of nephrocalcinosis sometimes seen in GGM. Furthermore, a novel intronic SGLT1 mutation (c.207+2dup) is described. Conclusion: These 2 cases demonstrate that a malabsorption disorder such as GGM can present with nephrocalcinosis and/or hypercalcemia, with increased 1,25(OH)2D3 levels in infants. Prompt recognition of GGM is sometimes difficult but crucial.

After the 2016 guidelines for blood pressure measurement, diagnosis, and investigation of pediatric hypertension, we now present evidence-based guidelines for the prevention and treatment of hypertension in children. These guidelines were developed by Hypertension Canada's Guideline Committee pediatric subgroup after thorough evaluation of the available literature. Included are 10 guidelines specifically addressing health behaviour management, indications for drug therapy in children with hypertension, choice of therapy for children with primary hypertension, and goals of therapy for children with hypertension. Although the pediatric literature is inherently limited by small numbers of participants, fewer trials, and a prolonged latency to the development of vascular outcomes, this report reflects the current and highest level of evidence and provides guidance for primary care practitioners on the management of pediatric hypertension. Studies of therapeutic lifestyle modifications in children are available to guide current management and more antihypertensive drugs have been studied in children since the Food and Drug Administration Modernization Act. Consistent with Hypertension Canada's guideline policy, diagnostic and therapeutic algorithm tools will be developed and the guidelines will be reviewed annually and updated according to new evidence.

We present the inaugural evidence-based Canadian recommendations for the measurement of blood pressure in children and the diagnosis and evaluation of pediatric hypertension. Rates of pediatric hypertension are increasing concomitant with increased rates of childhood obesity. With this, there is growing awareness of the need to measure blood pressure in children. Consequently, the present recommendations have been developed to address an important gap and improve the clinical care of children. For 2016, a total of 15 recommendations are presented. These are categorized in a fashion similar to that of the existing adult recommendations. Specifically, we present recommendations on (1) accurate measurement of blood pressure in children, (2) criteria for diagnosis of hypertension in children, (3) assessment of overall cardiovascular risk in hypertensive children, (4) routine laboratory tests for the investigation of children with hypertension, (5) ambulatory blood pressure measurement in children, and (6) the role of echocardiography. We discuss the rationale for the recommendations and present additional supporting material for the clinician, including tables with standardized techniques for blood pressure measurement and determination of normative blood pressure values for children. Hypertension Canada's Canadian Hypertension Education Program Guidelines Task Force will update the recommendations annually and develop future evidence-based recommendations to guide prevention and treatment of pediatric hypertension.

Background: Nephrotic syndrome is a commonly acquired kidney disease in children that causes significant morbidity due to recurrent episodes of heavy proteinuria. The management of childhood nephrotic syndrome is known to be highly variable among physicians and care centres. Objectives: The primary objective of the study is to determine centre-, physician-, and patient-level characteristics associated with steroid exposure and length of steroid treatment. We will also determine the association of dose and duration of steroid treatment and time to first relapse as a secondary aim. An embedded qualitative study utilizing focus groups with health care providers will enrich the quantitative results by providing an understanding of the attitudes, beliefs and local contextual factors driving variation in care. Design: Mixed-methods study; prospective observational cohort (quantitative component), with additional semi-structured focus groups of healthcare professionals (qualitative component). Setting: National study, comprised of all 13 Canadian pediatric nephrology clinics. Patients: 400 patients under 18 years of age to be recruited over 2.5 years. Measurements: Steroid doses for all episodes (first presentation, first and subsequent relapses) tracked over course of the study. Physician and centre-level characteristics catalogued, with reasons for treatment preferences documented during focus groups. Methods: All patients tracked prospectively over the course of the study, with data comprising a prospective registry. One focus group at each site to enrich understanding of variation in care. Limitations: Contamination of treatment protocols between physicians may occur as a result of concurrent focus groups. Conclusions: Quantitative and qualitative results will be integrated at end of study and will collectively inform strategies for the development and implementation of standardized evidence-based protocols across centres.

Preterm neonates are exposed at birth to high oxygen concentrations relative to the intrauterine environment. We have previously shown in a rat model that a hyperoxic insult results in a reduced nephron number in adulthood. Therefore, the aim of this study was to determine the effects of transient neonatal hyperoxia exposure on nephrogenesis. Sprague-Dawley rat pups were raised in 80% O2 or room air from P3 to P10. Pups (n = 12/group, 6 males and 6 females) were sacrificed at P5 (during active nephrogenesis) and at P10 (after the completion of nephrogenesis). Hyperoxia exposure resulted in a significant reduction in both nephrogenic zone width and glomerular diameter at P5, and a significantly increased apoptotic cell count; however, nephron number at P10 was not affected. HIF-1α expression in the developing kidney was significantly reduced following hyperoxia exposure. Systemic administration of the HIF-1α stabilizer dimethyloxalylglycine (DMOG) resulted in enhanced expression of HIF-1α and improved nephrogenesis: kidneys from hyperoxia-exposed pups treated with DMOG exhibited a nephrogenic zone width and glomerular diameter similar to room-air controls. These findings demonstrate that neonatal hyperoxia exposure results in impaired nephrogenesis, which may be at least in part HIF-1α-mediated. Although nephron number was not significantly reduced at the completion of nephrogenesis, early indicators of maldevelopment suggest the potential for accelerated nephron loss in adulthood. Overall, this study supports the premise that prematurely born neonates exposed to high oxygen levels after birth are vulnerable to impaired renal development.

The Canadian Hypertension Education Program reviews the hypertension literature annually and provides detailed recommendations regarding hypertension diagnosis, assessment, prevention, and treatment. This report provides the updated evidence-based recommendations for 2015. This year, 4 new recommendations were added and 2 existing recommendations were modified. A revised algorithm for the diagnosis of hypertension is presented. Two major changes are proposed: (1) measurement using validated electronic (oscillometric) upper arm devices is preferred over auscultation for accurate office blood pressure measurement; (2) if the visit 1 mean blood pressure is increased but < 180/110 mm Hg, out-of-office blood pressure measurements using ambulatory blood pressure monitoring (preferably) or home blood pressure monitoring should be performed before visit 2 to rule out white coat hypertension, for which pharmacologic treatment is not recommended. A standardized ambulatory blood pressure monitoring protocol and an update on automated office blood pressure are also presented. Several other recommendations on accurate measurement of blood pressure and criteria for diagnosis of hypertension have been reorganized. Two other new recommendations refer to smoking cessation: (1) tobacco use status should be updated regularly and advice to quit smoking should be provided; and (2) advice in combination with pharmacotherapy for smoking cessation should be offered to all smokers. The following recommendations were modified: (1) renal artery stenosis should be primarily managed medically; and (2) renal artery angioplasty and stenting could be considered for patients with renal artery stenosis and complicated, uncontrolled hypertension. The rationale for these recommendation changes is discussed.

BACKGROUND Charcot-Marie-Tooth neuropathy has been reported to be associated with renal diseases, mostly focal segmental glomerulosclerosis (FSGS). However, the common mechanisms underlying the neuropathy and FSGS remain unknown. Mutations in INF2 were recently identified in patients with autosomal dominant FSGS. INF2 encodes a formin protein that interacts with the Rho-GTPase CDC42 and myelin and lymphocyte protein (MAL) that are implicated in essential steps of myelination and myelin maintenance. We therefore hypothesized that INF2 may be responsible for cases of Charcot-Marie-Tooth neuropathy associated with FSGS.METHODS We performed direct genotyping of INF2 in 16 index patients with Charcot-Marie-Tooth neuropathy and FSGS who did not have a mutation in PMP22 or MPZ, encoding peripheral myelin protein 22 and myelin protein zero, respectively. Histologic and functional studies were also conducted.RESULTS We identified nine new heterozygous mutations in 12 of the 16 index patients (75%), all located in exons 2 and 3, encoding the diaphanous-inhibitory domain of INF2. Patients presented with an intermediate form of Charcot-Marie-Tooth neuropathy as well as a glomerulopathy with FSGS on kidney biopsy. Immunohistochemical analysis revealed strong INF2 expression in Schwann-cell cytoplasm and podocytes. Moreover, we demonstrated that INF2 colocalizes and interacts with MAL in Schwann cells. The INF2 mutants perturbed the INF2-MAL-CDC42 pathway, resulting in cytoskeleton disorganization, enhanced INF2 binding to CDC42 and mislocalization of INF2, MAL, and CDC42.CONCLUSIONS INF2 mutations appear to cause many cases of FSGS-associated Charcot-Marie-Tooth neuropathy, showing that INF2 is involved in a disease affecting both the kidney glomerulus and the peripheral nervous system. These findings provide new insights into the pathophysiological mechanisms linking formin proteins to podocyte and Schwanncell function. (Funded by the Agence Nationale de la Recherche and others.)