Nephrol Ther

La néphrocalcinose est définie par des dépôts de phosphate de calcium ou d’oxalate de calcium dans le parenchyme rénal, en particulier dans les cellules épithéliales des tubules rénaux et dans le tissu interstitiel. Il faut la différencier des néphrolithiases où les dépôts calciques se situent dans les cavités excrétrices rénales. La néphrocalcinose chez l’enfant n’est pas si rare, avec une augmentation de son incidence chez les enfants nés prématurément. Souvent de découverte fortuite, ses étiologies sont multiples et peuvent être classées en fonction du type radiologique de néphrocalcinose : médullaire, corticale ou mixte (diffuse). Les causes principales retrouvées chez l’enfant concernent la néphrocalcinose médullaire et comportent les tubulopathies héréditaires, en particulier l’acidose tubulaire distale et la maladie de Dent, les anomalies métaboliques telles que l’hypercalciurie idiopathique et les hyperoxaluries, et les formes iatrogènes secondaires, notamment aux surdosages en vitamine D. Chez le nouveau-né, il s’agit principalement de l’hypercalciurie du prématuré dont l’origine, multifactorielle, est en grande partie iatrogène. L’hyperoxalurie primitive, qui entraîne une néphrocalcinose diffuse d’apparition précoce et conduit à une insuffisance rénale chronique, ne doit pas être méconnue et systématiquement être recherchée. Afin de pouvoir établir un diagnostic spécifique, il est essentiel de prendre en compte l’anamnèse familiale, le contexte clinique ainsi que les données biologiques complètes. Instituer précocement un traitement étiologique adapté permettrait de prévenir ou de retarder l’évolution vers une insuffisance rénale chronique.Nephrocalcinosis is defined by calcium phosphate or calcium oxalate deposits in the kidney parenchyma, particularly in tubular epithelial cells and interstitial tissue. It should be differentiated from urolithiasis where calcium salts deposits are located in the kidney and urinary tract. The epidemiology of nephrocalcinosis in children is unknown but the condition is not so rare, with an increased incidence in preterm infants. Often detected as an incidental finding, nephrocalcinosis may be classified according to the radiological type: medullary, cortical or diffuse. Nephrocalcinosis in children can be caused by a variety of etiology. The most common causes concern medullary nephrocalcinosis and include hereditary tubular disorders, in particular distal renal tubular acidosis and Dent disease, metabolic disorders such as idiopathic hypercalciuria and hyperoxaluria, and iatrogenic causes such as vitamin D intoxication. In the newborn, the main cause is hypercalciuria of the premature baby, whose multifactorial origin is largely iatrogenic. Primary hyperoxaluria which can lead to early onset nephrocalcinosis and usually to chronic kidney disease should always be considered and further investigated. In order to provide a specific diagnosis, it is essential to take into account the family history, the clinical context and complete laboratory data. Early initiation of an appropriate etiological treatment is recommended and may prevent or delay the progression to chronic kidney disease in some cases

Cardiac involvement in pediatric hemolytic uremic syndrome.

International audienceBackgroundCardiac involvement is a known but rare complication of pediatric hemolytic uremic syndrome (HUS). We conducted a nationwide observational, retrospective case–control study describing factors associated with the occurrence of myocarditis among HUS patients.MethodsCases were defined as hospitalized children affected by any form of HUS with co-existent myocarditis in 8 French Pediatric Intensive Care Units (PICU) between January 2007 and December 2018. Control subjects were children, consecutively admitted with any form of HUS without coexistent myocarditis, at a single PICU in Lyon, France, during the same time period.ResultsA total of 20 cases of myocarditis were reported among 8 PICUs, with a mean age of 34.3 ± 31.9 months; 66 controls were identified. There were no differences between the two groups concerning the season and the typical, Shiga toxin-producing Escherichia coli (STEC-HUS), or atypical HUS (aHUS). Maximal leukocyte count was higher in the myocarditis group (29.1 ± 16.3G/L versus 21.0 ± 9.9G/L, p = 0.04). The median time between admission and first cardiac symptoms was of 3 days (range 0–19 days), and 4 patients displayed myocarditis at admission. The fatality rate in the myocarditis group was higher than in the control group (40.0% versus 1.5%, p < 0.001). Thirteen (65%) children from the myocarditis group received platelet transfusion compared to 19 (29%) in the control group (p = 0.03).ConclusionOur study confirms that myocarditis is potentially lethal and identifies higher leukocyte count and platelet transfusion as possible risk factors of myocarditis