[The glomerulus in all its states]. / Le glomérule dans tous ses états.

Glomerulonephritis are the result of an inflammatory hit to the glomerulus. They are rare and heterogeneous renal diseases. Each glomerular compartment can be affected. The clinical manifestations present with hematuria, proteinuria and/or impaired renal function, either isolated or combined. Two main clinico-biological syndromes are described: nephrotic syndrome and nephritic syndrome. The latter can present in a more severe form i.e. rapidly progressive glomerulonephritis with the worst prognosis. These different clinical pictures are related to specific glomerular lesions. Thus, podocytic damage is mainly responsible for nephrotic syndromes, mesangial damage is responsible for proteinuria and hematuria and, finally, endothelial damage is responsible for nephritic syndrome and rapidly progressive glomerulonephritis. Therapeutic approaches include non-specific measures, combining both life-style and pharmacological interventions with the aim to reduce risk factors, and specific measures with the use of different immunosuppressive agents.

: Les glomérulonéphrites sont des atteintes inflammatoires du glomérule. Il s'agit de pathologies rénales rares et hétérogènes. Tous les compartiments glomérulaires peuvent être touchés. Les répercussions cliniques sont diverses. Elles se manifestent par une hématurie, une protéinurie et/ou une altération de la fonction rénale, présente chacune de manière isolée ou combinée. Deux principaux syndromes clinico-biologiques sont décrits : le syndrome néphrotique et le syndrome néphritique. Au sein de cette dernière entité, on distingue une forme plus sévère, les glomérulonéphrites rapidement progressives grevées du plus mauvais pronostic. Ces différents tableaux cliniques sont en lien avec des lésions glomérulaires spécifiques. Ainsi, les atteintes podocytaires sont principalement responsables des syndromes néphrotiques, les atteintes mésangiales sont responsables de protéinurie et d'hématurie et les atteintes endothéliales sont responsables de syndromes néphritiques et de glomérulonéphrites rapidement progressives. Les approches thérapeutiques comprennent des mesures non spécifiques, hygiéno-diététiques et pharmacologiques, visant à réduire les différents facteurs de risque, et des mesures spécifiques avec l'utilisation de divers médicaments immunosuppresseurs.

[Diagnosis and management of renal allograft rejection]. / Diagnostic et prise en charge thérapeutique du rejet en transplantation rénale.

Renal allograft rejection involves many mechanisms of innate and adaptive immunity, responsible for parenchymal inflammatory lesions that negatively impact the long-term outcomes of the renal allograft. The heterogeneous presentations of rejections in terms of clinical, biological and histological aspects make them difficult to manage in daily clinical practice. Indeed, current therapeutic strategies are disappointing in term of long-term outcomes, including graft survival. In this article, we will discuss the main effector mechanisms of rejection and their histological classification, as well as the existing treatments and those currently under evaluation.

: Le rejet du greffon rénal fait intervenir de nombreux mécanismes de l'immunité innée et adaptative, responsables de lésions inflammatoires parenchymateuses impactant négativement le devenir au long cours du greffon rénal. La grande hétérogénéité dans la présentation clinique, biologique et histologique des rejets de greffe en fait des entités difficiles à prendre en charge en pratique clinique quotidienne. En effet, les stratégies thérapeutiques actuelles montrent des résultats assez décevants pour le traitement des rejets, ce qui a comme conséquence une diminution significative de la survie des greffons. Nous aborderons dans cet article les principaux mécanismes effecteurs des rejets, leur classification histologique ainsi que les traitements existants et en cours de validation.

[18F]FDG PET/CT imaging disproves renal allograft acute rejection in kidney transplant recipients with acute kidney dysfunction: a validation cohort.

PURPOSE: [18F]FDG PET/CT may predict the absence of acute allograft rejection (AR) in kidney transplant recipients (KTRs) with acute kidney injury (AKI). Still, the proposed threshold of 1.6 of the mean of mean standardized uptake values (mSUVmean) in the renal parenchyma needs validation. METHODS: We prospectively performed 86 [18F]FDG PET/CT in 79 adult KTRs who underwent per-cause transplant biopsy for suspected AR. Biopsy-proven polyoma BK nephropathies (n = 7) were excluded. PET/CT was performed 192 ± 18 min after administration of 254.4 ± 30.4 MBq of [18F]FDG. The SUVmean was measured in both upper and lower poles of the renal allograft. One-way analysis of variance (ANOVA) and Tukey's studentized range test were sequentially performed. The receiver operating characteristic (ROC) curve was drawn to discriminate "AR" from non-pathological ("normal" + "borderline") conditions. RESULTS: The median age of the cohort was 55 [43; 63] years, with M/F gender ratio of 47/39. The mean eGFR was 31.9 ± 14.6 ml/min/1.73m2. Biopsies were categorized in 4 groups: "normal" (n = 54), "borderline" (n = 9), "AR" (n = 14), or "others" (n = 2). The median [min; max] mSUVmean reached 1.72 [1.02; 2.07], 1.97 [1.55; 2.11], 2.13 [1.65, 3.12], and 1.84 [1.57; 2.12] in "normal," "borderline," "AR," and "others" groups, respectively. ANOVA demonstrated a significant difference of mSUVmean among groups (F = 13.25, p < 0.0001). The ROC area under the curve was 0.86. Test sensitivity and specificity corresponding to the threshold value of 1.6 were 100% and 30%, respectively. CONCLUSION: [18F]FDG PET/CT may help noninvasively prevent inessential transplant biopsies in KTR with AKI.

[Kidney injury in COVID-19]. / Atteintes rénales de la COVID-19.

The SARS-CoV-2 virus causes a respiratory distress syndrome, the main symptom of COVID-19 (for "COronaVIrus Disease 2019"). This infectious disease has been causing a major health and socio-economic pandemic since December 2019. The pulmonary alveolus is regarded as the main target of SARS-CoV-2. However, this coronavirus is capable of directly or indirectly affecting other organs, including the kidneys. Here, we summarize the presumed pathophysiology of COVID-19 renal disease. The incidence of acute kidney injury ranges from 0,5 to 22 % of all patients infected with SARS-CoV-2. The need for renal replacement therapy is reported in 5-9 % of patients in intensive care. Histological analysis of renal biopsies mainly shows acute tubular necrosis of varying severity, as well as the congestion of glomerular and peri-tubular capillaries. Endothelitis has been described in few cases. Evidence for a factual inflammation of the glomerulus remains controversial. The medium/long term consequences of COVID-19 nephropathy are unknown and will deserve a tight follow-up.

Le virus SARS-CoV-2 provoque un syndrome de détresse respiratoire aiguë, le symptôme principal de l'infection COVID-19 (pour «COronaVIrus Disease 2019¼). Cette maladie infectieuse provoque une pandémie de gravité sanitaire et socio-économique majeure depuis décembre 2019. La cible principale du SARS-CoV-2 serait l'alvéole pulmonaire. Néanmoins, ce coronavirus est capable d'affecter directement ou indirectement d'autres organes, y compris les reins. Nous résumons ici la physiopathologie présumée de l'atteinte rénale de la COVID-19. L'incidence de l'insuffisance rénale aiguë varie entre 0,5 à 22 % de tous les patients infectés par le SARS-CoV-2. La nécessité d'une épuration extra-rénale est rapportée chez 5-9 % des patients pris en charge aux soins intensifs. L'analyse histologique de biopsies rénales montre, principalement, une nécrose tubulaire aiguë de sévérité variable, ainsi qu'une congestion des capillaires glomérulaires et péri-tubulaires. Une endothélite a parfois été décrite. L'atteinte inflammatoire du glomérule reste débattue. Les conséquences à moyen/long termes de la néphropathie COVID-19 sont inconnues et mériteront un suivi étroit.

[Malabsorption of thyroid hormones ... or simply poor patient compliance?]. / Malabsorption des hormones thyroïdiennes ... ou simple manque de compliance?

We report the case of a patient presenting with L-thyroxine pseudomalabsorbtion, a figure in which patients are in a state of biological, and, frequently, clinical hypothyroidism secondary to a lack of adherence to substitutive thyroid treatment. We then review the different causes of true thyroid hormones malabsorption and the different approaches to these situations. We also suggest diagnostic and therapeutic attitudes for clinicians facing suspicious cases of hormone malabsorption.

[Medication of the month. Febuxostat (Adenuric)]. / Le médicament du mois. Fébuxostat (Adenuric).

Gout is a rheumatologic disease due to the deposition of urate (the catabolite of purines) crystals within joints. Prevalence of the disease is high. Potential articular and nephrological complications are numerous. Therefore, a chronic, preventive and effective therapy is required in specific patients. Dietary changes are frequently insufficient and urate-lowering therapy is thus necessary, like uricosuric or xanthine oxydase inhibitors. The objective of these therapies is to lower serum urate levels below 6 mg/dL. The xanthine oxydase inhibitor allopurinol is still the most used in the context of gout prevention. However, allopurinol tolerance and efficacy are far from optimal. Now, a new therapy is available in Belgium, the febuxostat. Febuxostat is a new xanthine oxidase inhibitor.Tolerance and therapeutic effect seem better compared to allopurinol. In this article, we review pharmacological data about this new treatment. We also review the most important clinical trials underlining strengths and limitations of febuxostat.

[A rare cause of acute renal failure, acute tubulo-interstitial nephritis]. / La néphropathie tubulo-interstitielle aiguë: une cause rare d'insuffisance rénale aiguë.

We report the case of an acute renal failure due to an acute interstitial nephropathy (ATIN) induced by non steroidal anti-inflammatory drugs (NSAID). Even though this pathology is a rare cause of acute renal failure, it still requires special attention in view of the fact that it induces a high risk of acute morbidity but it also can evolve into chronic renal failure. Its differential diagnosis with other causes of acute renal failure becomes essential because of the different therapeutic care. In this article, we are going to briefly sum up the reasoning to adopt in order to diagnose an acute renal failure.