Contrast-enhanced ultrasonography reveals a lower cortical perfusion and a decreased renal flow reserve in hypertensive patients.

BACKGROUND: Microvascular structural alteration and dysfunction is a hallmark of arterial hypertension. So far, the visualization and the quantification of renal microcirculation in humans has been hampered by the lack of non-nephrotoxic and non-invasive radiologic techniques. Contrast-enhanced ultrasonography (CEUS) is an appealing method to investigate renal microcirculation and has not been investigated in this setting. We aimed to compare renal microcirculation in normotensive (NT) and hypertensive (HT) participants using CEUS at rest and during a sympathetic stress test. METHODS: We measured the renal perfusion index (PI, primary outcome), the renal resistive index (RRI), beat-to-beat systemic hemodynamics and plasma catecholamines before and during a 2-min cold pressor test (CPT) in NT and HT participants. Linear mixed model analysis was used to compare the effect of the CPT on the variables of interest. RESULTS: Seventy-three participants (32 HT) with normal kidney function were included. HT participants had a lower baseline PI compared with NT participants [median (interquartile range) 1476 (959-2155) arbitrary units (a.u.) vs 2062 (1438-3318) a.u., P < .001]. The CPT increased blood pressure, heart rate and catecholamines in all participants. The increase in PI observed in NT during the CPT was blunted in HT [+504 (117-920) a.u. vs +1159 (678-2352) a.u in NT, interaction P = .013]. Age, sex and body mass index did not modify these results. CONCLUSIONS: HT patients had a lower basal renal cortical perfusion. During the cold pressor test, HT participants had a smaller increase in the PI, suggesting that renal cortical flow reserve is impaired.

A new, deep learning-based method for the analysis of autopsy kidney samples used to study sex differences in glomerular density and size in a forensic population.

Artificial intelligence (AI) is increasingly used in forensic anthropology and genetics to identify the victim and the cause of death. The large autopsy samples from persons with traumatic causes of death but without comorbidities also offer possibilities to analyze normal histology with AI. We propose a new deep learning-based method to rapidly count glomerular number and measure glomerular density (GD) and volume in post-mortem kidney samples obtained in a forensic population. We assessed whether this new method detects glomerular differences between men and women without known kidney disease. Autopsies performed between 2009 and 2015 were analyzed if subjects were aged ≥ 18 years and had no known kidney disease, diabetes mellitus, or hypertension. A large biopsy was taken from each kidney, stained with hematoxylin and eosin, and scanned. An in-house developed deep learning-based algorithm counted the glomerular density (GD), number, and size. Out of 1165 forensic autopsies, 86 met all inclusion criteria (54 men). Mean (± SD) age was 43.5 ± 14.6; 786 ± 277 glomeruli were analyzed per individual. There was no significant difference in GD between men and women (2.18 ± 0.49 vs. 2.30 ± 0.57 glomeruli/mm2, p = 0.71); glomerular diameter, area, and volume also did not differ. GD correlated inversely with age, kidney weight, and glomerular area. Glomerular area and volume increased significantly with age. In this study, there were no sex differences in glomerular density or size. Considering the size of the kidney samples, the use of the presented deep learning method can help to analyze large renal autopsy biopsies and opens perspectives for the histological study of other organs.

Reference values for plasma and urine trace elements in a Swiss population-based cohort.

OBJECTIVES: Trace elements (TEs) are ubiquitous. TE concentrations vary among individuals and countries, depending on factors such as living area, workplaces and diet. Deficit or excessive TEs concentrations have consequences on the proper functioning of human organism so their biomonitoring is important. The aim of this project was to provide reference values for TEs concentrations in the Swiss population. METHODS: The 1,078 participants to the SKiPOGH cohort included in this study were aged 18-90 years. Their 24-h urine and/or plasma samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to determine 24 TEs concentrations: Ag, Al, As, Be, Bi, Cd, Co, Cr, Cu, Hg, I, Li, Mn, Mo, Ni, Pb, Pd, Pt, Sb, Se, Sn, Tl, V and Zn. Statistical tests were performed to evaluate the influence of covariates (sex, age, BMI, smoking) on these results. Reference intervals for the Swiss adult population were also defined. RESULTS: TEs concentrations were obtained for respectively 994 and 903 persons in plasma and urine matrices. It was possible to define percentiles of interest (P50 and P95) for almost all the TEs. Differences in TEs distribution between men and women were noticed in both matrices; age was also a cofactor. CONCLUSIONS: This first Swiss biomonitoring of a large TEs-panel offers reference values in plasma and in urine for the Swiss population. The results obtained in this study were generally in line with clinical recommendations and comparable to levels reported in other population-based surveys.

Self-reported caffeine consumption miss-matched consumption measured by plasma levels of caffeine and its metabolites: results from two population-based studies.

IMPORTANCE AND OBJECTIVE: Self-reported caffeine consumption has been widely used in research while it may be subject to bias. We sought to investigate the associations between self-reported caffeine consumption and plasma levels of caffeine and its two main metabolites (paraxanthine and theophylline) in the community. METHODS: Data from two population-based studies (SKIPOGH1 and 2 (N = 1246) and CoLaus|PsyCoLaus (N = 4461)) conducted in Switzerland were used. Self-reported caffeine consumption was assessed using questionnaires. Plasma levels of caffeine and its metabolites were quantified by ultra-high performance liquid chromatography coupled to a tandem quadrupole mass spectrometer. RESULTS: In both studies, mean log plasma levels of caffeine and its two metabolites were over 6.48 (plasma levels = 652 ng/ml) when no caffeine consumption was reported. Subsequently, nonlinear associations between log plasma levels and self-reported caffeine consumption were observed in SKIPOGH, with a change of the slope at 3-5 cups of espresso per day in SKIPOGH1 but not SKIPOGH2. In CoLaus|PsyCoLaus, increased daily consumption of caffeinated beverages was associated with increased log plasma levels with a change of the slope at 3 cups. In both studies, declared caffeine consumption higher than 3-5 cups per day was not associated with higher plasma levels of caffeine and its metabolites. CONCLUSION: Self-reports of no or low caffeine consumption and consumption of more than 3-5 cups of coffee should be interpreted with caution, with possible under- or over-estimation. Quantifying plasma levels of caffeine and its metabolites may contribute to a better estimation of caffeine intake.

The urine-to-plasma urea concentration ratio is associated with eGFR and eGFR decline over time in a population cohort.

BACKGROUND: Evaluation of renal function and of factors associated with its decline are important public health issues. Besides markers of glomerular function [e.g. glomerular filtration rate (GFR)], those of tubular functions are rarely evaluated. Urea, the most abundant urinary solute, is markedly concentrated in urine when compared with plasma. We explored the urine-to-plasma ratio of urea concentrations (U/P urea ratio) as a marker of tubular functions. METHODS: We evaluated the relationship of the U/P urea ratio with eGFR at baseline in 1043 participants (48 ± 17 years) from the Swiss Kidney Project on Genes in Hypertension (SKIPOGH) population-based cohort, using mixed regression. In 898 participants, we assessed the relation between U/P urea ratio and renal function decline between two study waves 3 years apart. We studied U/P ratios for osmolarity, Na, K and uric acid for comparison. RESULTS: In a transversal study at baseline, estimated GFR (eGFR) was positively associated with U/P-urea ratio [ßscaled = 0.08, 95% CI (0.04; 0.13)] but not with the U/P ratio of osmolarity. Considering separately participants with renal function >90 or ≤90 mL/min × 1.73 m2, this association was observed only in those with reduced renal function. In the longitudinal study, eGFR declined at a mean rate of 1.2 mL/min per year. A significant association was observed between baseline U/P urea ratio and eGFR decline [ßscaled = 0.08, 95% CI (0.01; 0.15)]. A lower baseline U/P urea ratio was associated with a greater eGFR decline. CONCLUSION: This study provides evidence that the U/P urea ratio is an early marker of kidney function decline in the general adult population. Urea is easy to measure with well-standardized techniques and at low cost. Thus, the U/P urea ratio could become an easily available tubular marker for evaluating renal function decline.

Empagliflozin Changes Urine Supersaturation by Decreasing pH and Increasing Citrate.

Clinical Trial registry name and registration number: Empagliflozin and Renal Oxygenation in Healthy Volunteers (EMPA-REIN), NCT03093103.

[Intravenous drug use and kidney disease]. / Consommation de drogues par voie itraveineuse et maladies rénales.

Intravenous drug use (IVDU) is a major public health issue, associated with high mortality rates. The risk of overdose, cardiovascular and infectious complications are well known, but IVDU can also lead to different types of kidney disease. Patients can develop acute or chronic kidney injury due to direct nephrotoxicity of the drugs, or present with different types of glomerulonephritis, interstitial nephritis, and bacterial or viral infection-related nephropathy. Diagnosis can be difficult but is essential to prevent irreversible kidney damage. The number of persons with IVDU that develop end-stage kidney disease is increasing and poses challenges for dialysis and transplantation centers. This article summarizes the renal manifestations that clinicians may encounter in persons with IVDU, especially of heroin and cocaine.

La consommation de drogues par voie intraveineuse (CDVI) constitue un problème majeur de santé publique. Les risques d'overdose, de complications cardiovasculaires et infectieuses sont bien connus, mais la CDVI peut aussi mener à différentes atteintes rénales. Les patients peuvent développer une insuffisance rénale aiguë ou chronique due à la toxicité directe des drogues, mais aussi une glomérulonéphrite, une néphrite interstitielle ou une néphropathie secondaire à une infection virale ou bactérienne. Le nombre de personnes avec CDVI développant une insuffisance rénale terminale est à la hausse et représente un défi pour les centres de dialyse et de transplantation. Cet article passe en revue les manifestations rénales que les cliniciens peuvent rencontrer lors de la prise en charge de patients avec CDVI, notamment d'héroïne et de cocaïne.

[Estimating renal function in older patients : which is the best formula?] / Estimation de la fonction rénale chez la personne âgée : quelle formule utiliser ?

An accurate assessment of renal function is crucial for the diagnosis and follow up of kidney diseases. However, there is currently no clear consensus on the optimal method on how to measure renal function in older individuals (>65 years of age). The Cockcroft-Gault formula, the MDRD equation, and the CKD-EPI equation are among the most used equations. However, they have several limitations when applied to the older population. Other formulas specifically developed for the older, such as the Berlin Initiative Study (BIS) and the Full Age Spectrum (FAS) equation, demonstrated conflicting results and require more external validation. This article provides an overview of the currently available methods to assess renal function in the older persons and summarizes their shortcomings.

Une évaluation correcte de la fonction rénale est essentielle pour diagnostiquer et prendre des décisions cliniques importantes. Cependant, il n'y a pas de consensus clair sur la meilleure méthode pour mesurer la fonction rénale chez les personnes âgées. Les équations les plus couramment utilisées sont la formule de Cockcroft-Gault et les équations MDRD et CKD-EPI, mais elles présentent des limitations dans cette population. D'autres formules spécifiquement développées pour les aînés, telles que l'étude de l'initiative de Berlin (BIS) et l'équation du spectre complet de l'âge (FAS), ont montré des résultats contradictoires et nécessitent des études de validation externe. En conclusion, les médecins doivent être conscients des différentes options disponibles et des limitations de chaque méthode pour prendre des décisions cliniques éclairées.

Metformin versus SGLT-2 inhibitors: how low can we go?

The progression of chronic kidney disease is difficult to stop once established. Metformin and sodium-glucose cotransporter 2 inhibitors show promise, but clinical trials with a head-to-head comparison in patients with more advanced (stage 3b-4) chronic kidney disease are largely lacking, partly for safety reasons. In this issue, Corremans et al. compare the effects of metformin and canagliflozin in rats with adenine-induced moderate (stage 2-4) chronic kidney disease. Metformin halted progression, whereas canagliflozin did not. This commentary puts the results in a wider clinical context.

Changes of lipoprotein(a) levels with endogenous steroid hormones.

BACKGROUND: Lipoprotein(a) [Lp(a)] is an LDL-like molecule that is likely causal for cardiovascular events and Lp(a) variability has been shown to be mostly of genetic origin. Exogenous hormones (hormone replacement therapy) seem to influence Lp(a) levels, but the impact of endogenous hormone levels on Lp(a) is still unknown. The aim of the study was to assess the effect of endogenous steroid hormone metabolites on Lp(a). METHODS: Lipoprotein(a) levels were measured in 1,021 participants from the Swiss Kidney Project on Genes in Hypertension, a family-based, multicentre, population-based prospective cohort study. Endogenous levels of 28 steroid hormone precursors were measured in 24-h urine collections from 883 individuals. Of the participants with Lp(a) data, 1,011 participants had also genotypes available. RESULTS: The participants had an average age of 51 years and 53% were female. Median Lp(a) levels were 62 mg/L, and the 90th percentile was 616 mg/L. The prevalence of a Lp(a) elevation ≥700 mg/L was 3.2%. Forty-three per cent of Lp(a) variability was explained respectively by: age (2%, p < .001), LDL-C (1%, p = .001), and two SNPs (39%, p value<2⋅10-16 ). Of the 28 endogenous steroid hormones assessed, androstenetriol, androsterone, 16α-OH-DHEA and estriol were nominatively associated with serum Lp(a) levels in univariable analyses and explained 0.4%-1% of Lp(a) variability, but none of them reached significance in multivariable models. CONCLUSIONS: In this contemporary population-based study, the prevalence of a Lp(a) elevation ≥700 mg/L was 3.2%. The effect of endogenous steroid hormone levels of Lp(a) variability was small at best, suggesting a negligible impact on the wide range of Lp(a) variability.

Cortical perfusion as assessed with contrast-enhanced ultrasound is lower in patients with chronic kidney disease than in healthy subjects but increases under low salt conditions.

BACKGROUND: Disturbances in renal microcirculation play an important role in the pathophysiology of chronic kidney disease (CKD), but the lack of easy accessible techniques hampers our understanding of the regulation of the renal microcirculation in humans. We assessed whether contrast-enhanced ultrasound (CEUS) can identify differences in cortical perfusion and alterations induced by different dietary salt intakes in CKD patients and controls. METHODS: Participants underwent CEUS twice: once after 5 days of high-salt (HS) intake, and again after 5 days of low salt (LS) diet. Sonovue® (0.015 mL/kg/min) was perfused as contrast agent and four consecutive destruction-reperfusion sequences were analysed per visit. The primary outcome measure was the (change in) mean perfusion index (PI) of the renal cortex. RESULTS: Forty healthy volunteers (mean age ± standard deviation 50 ± 8 years) and 18 CKD Stages 2-4 patients [aged 55 ± 11 years, estimated glomerular filtration rate (eGFR) 54 ± 28 mL/min/1.73 m2] were included and underwent CEUS without side effects. Under HS conditions, cortical PI was significantly lower in CKD patients [1618 ± 1352 versus 3176 ± 2278 arbitrary units (a.u) in controls, P = 0.034]. Under LS, renal PI increased in CKD patients (with +1098 to 2716 ± 1540 a.u., P = 0.048), whereas PI remained stable in controls. In the continuous analysis, PI correlated with eGFR (Spearman's r = 0.54, P = 0.005) but not with age, sex, blood pressure or aldosterone levels. CONCLUSIONS: CEUS identified important reductions in cortical micro-perfusion in patients with moderate CKD. Lowering salt intake increased perfusion in CKD patients, but not in controls, underlining the benefits of an LS diet in CKD patients. Whether a low PI is an early sign of kidney damage and predicts renal function decline needs further study.

Contrast-Enhanced Ultrasound and Protein Shakes Are No Alternatives for Inulin Clearance and Meat to Assess Renal Functional Reserve in Humans.

INTRODUCTION: The measurement of renal functional reserve (RFR) can unmask glomerular hyperfiltration in residual nephrons, but its determination is time-consuming. In this study, we assessed whether contrast-enhanced ultrasound (CEUS) is a valuable alternative to the gold standard inulin clearance and whether L-arginine or protein shakes lead to similar changes in glomerular filtration rate (GFR) as animal proteins in men and women. METHODS: Changes in GFR and renal microperfusion were studied in 25 healthy subjects (8 men, 17 women) by simultaneously performing inulin clearance and CEUS (perfusion index, PI) before and 1 and 2 h after different protein loads (L-arginine, protein shake or meat). The Doppler parameters - renal resistive index (RRI) and pulsatility index (PuI) - were also measured. RESULTS: None of the oral protein loads induced significant changes in CEUS-assessed PI. Only meat increased inulin clearance (from 111.2 ± 16.0 to 149.8 ± 27.2 mL/min, p < 0.05) and mobilized RFR, while L-arginine decreased GFR (106.7 ± 45.3 to 86.3 ± 42.6 mL/min, p < 0.05). Protein shakes had a neutral effect. There were no correlations between changes in inulin clearance and PI. At Doppler, RRI and PuI increased after meat intake (from 0.647 ± 0.029 to 0.694 ± 0.050 a.u., p < 0.05 and from 1.130 ± 0.087 to 1.318 ± 0.163 a.u., p < 0.05, respectively), but their changes also did not correlate with changes in inulin clearance. Results were similar in both sexes. CONCLUSIONS: CEUS is not a valuable alternative for inulin clearance to measure RFR. Meat ingestion leads to modest changes in renal Doppler parameters and to glomerular hyperfiltration in both women and men, while protein shakes and L-arginine do not.

PhenoExplorer: An Interactive Web-based Platform for Exploring (Epi)Genome-Wide Associations Using a Swiss Population-based Study.

The recent advent of high-throughput sequencing technologies has allowed exploring the contribution of thousands of genomic, epigenomic, transcriptomic, or proteomic variants to complex phenotypic traits. Here, we sought to conduct large-scale (Epi)Genome-Wide Association Studies (GWAS/EWAS) to investigate the associations between genomic (Single Nucleotide Polymorphism; SNP) and epigenomic (Cytosine-Phospho-Guanine; CpG) markers, with multiple phenotypic traits in a population-based context. We used data from SKIPOGH, a family- and population-based cohort conducted in the cities of Lausanne, Geneva, and Bern (N=1100). We used 7,577,572 SNPs, 420,444 CpGs, and 825 phenotypes, including anthropometric, clinical, blood, urine, metabolite, and metal measures. GWAS analyses assessed the associations between SNPs and metabolites and metals (N=279), using regression models adjusted for age, sex, recruitment center, and familial structure, whereas EWAS analyses explored the relations between CpGs and 825 phenotypes, additionally adjusting for the seasonality of blood sampling and technical nuisance. Following the implementation of GWAS and EWAS analyses, we developed a web-based platform, PhenoExplorer, aimed at providing an open access to the obtained results. Of the 279 phenotypes included in GWAS, 103 displayed significant associations with 2804 SNPs (2091 unique SNPs) at Bonferroni threshold, whereas 109 of the 825 phenotypes included in EWAS analyses were associated with 4893 CpGs (2578 unique CpGs). All of the obtained GWAS and EWAS results were eventually made available using the in-house built web-based PhenoExplorer platform, with the purpose of providing an open-access to the tested associations. In conclusion, we provide a comprehensive outline of GWAS and EWAS associations performed in a Swiss population-based study. Further, we set up a web-based PhenoExplorer platform with the purpose of contributing to the overall understanding of the role of molecular variants in regulating complex phenotypes.

[New insights in the pathophysiology and treatment of renal anemia]. / Nouveautés dans la pathophysiologie et le traitement de l'anémie rénale.

Renal anemia is a frequently encountered complication in patients suffering from advanced chronic kidney disease. This is mainly due to the decreased secretion of erythropoietin by the diseased kidneys. The current treatment of renal anemia is based on iron substitution and administration of recombinant erythropoietin. The discovery of HIF (Hypoxia-Inducible Factor) has led to the development of a new class of molecules that block the activity of prolyl-4-hydroxylases and stabilize HIF (Hypoxia-Inducible Factor), a transcription factor that plays an essential role in numerous cellular pathways, including those linked to erythropoiesis and iron metabolism. In this article, we discuss the current understanding of the pathophysiological mechanisms underlying renal anemia and the potential role of the new HIF-stabilizers in its treatment.

L'anémie rénale est un problème courant chez les patients souffrant d'insuffisance rénale chronique avancée. Elle est due essentiellement à la diminution de la sécrétion d'érythropoïétine par les reins malades. Le traitement actuel de l'anémie rénale repose sur la substitution martiale et l'administration d'érythropoïétine recombinante. Récemment, une nouvelle classe de molécules a été développée, dont l'effet repose sur l'inactivation des prolyl-4-hydroxylases, qui dégradent normalement l'HIF (Hypoxia- Inducible Factor), un facteur de transcription important dans l'expression des gènes liés à l'érythropoïèse et au métabolisme du fer. Dans cet article, nous ferons le point sur les connaissances actuelles de la pathophysiologie de l'anémie rénale et le rôle potentiel des inhibiteurs des prolyl-4-hydroxylases dans son traitement.

Dialysis initiation improves calcification propensity.

BACKGROUND: Cardiovascular morbidity and mortality is high in patients starting dialysis and could be related to modifications of calcification inducers and inhibitors by dialysis, promoting cardiovascular events. The impact of dialysis initiation on serum calcification propensity evolution and arterial stiffness is unknown. We therefore prospectively determined the evolution of the one-half maximal transition time (T50) value and its main determinants as well as pulse wave velocity over the first 3 months of dialysis initiation. METHODS: We analysed the evolution of T50, fetuin-A and mineral metabolism parameters before dialysis initiation (M0) and monthly until Month 3 (M3) in incident patients starting haemodialysis (HD) or peritoneal dialysis (PD) in two tertiary Swiss university hospitals. Arterial stiffness was assessed by pulse tonometry at M0 and M3 and biological parameters were compared between M0 and M3 and before/after HD. Linear mixed models were used to assess parameter evolution over time, taking into account repeated measures and other influencing variables. RESULTS: Forty-six patients on HD and 12 on PD were followed. Among them, 45 were male (78%) with a median age of 67 years (25th-75th quartile range 54-77). T50 significantly increased between M0 and M3 from 183 (120-266) to 246 min (175-330) (P < 0.001). Fetuin-A, calcium and magnesium also increased while phosphate decreased. Factors associated with T50 changes over time were fetuin-A, phosphate and magnesium (P < 0.001). Fetuin-A changes were associated with inflammation-related factors (albumin, C-reactive protein) but not calcium and phosphate levels. Arterial stiffness was not significantly modified over 3 months. PD and HD initiation showed similar trends. CONCLUSIONS: Dialysis initiation significantly improves calcification propensity and fetuin-A levels. These modifications do not explain the high mortality related to dialysis initiation. The clinical relevance of using T50 values to initiate dialysis awaits further studies.

Renal handling of zinc in chronic kidney disease patients and the role of circulating zinc levels in renal function decline.

BACKGROUND: Zinc deficiency is commonly encountered in chronic kidney disease (CKD). The aims of this study were to assess whether zinc deficiency was related to increased renal excretion of zinc and to the progression of CKD. METHODS: Plasma and 24-h urinary zinc levels, urinary electrolytes and uromodulin were measured in 108 CKD patients and 81 individuals without CKD. Serum creatinine values were collected for 3 years to calculate the yearly change in estimated glomerular filtration rate (eGFR). Multivariable regression analysis was performed to assess the association between baseline zinc levels and yearly change in eGFR. RESULTS: CKD patients had lower circulating zinc levels and higher 24-h urinary zinc excretion than non-CKD participants (612.4 ± 425.9 versus 479.2 ± 293.0 µg/day; P = 0.02). Fractional excretion (FE) of zinc was higher and it significantly increased at more advanced CKD stages. Zinc FE was correlated negatively with 24-h urinary uromodulin excretion (r=-0.29; P < 0.01). Lower baseline plasma zinc levels were associated with a faster yearly decline of renal function in age, gender, diabetes and hypertension adjusted models, but this relationship was no longer significant when baseline eGFR or proteinuria were included. CONCLUSIONS: Zinc levels are lower in CKD, and not compensated by reduced renal zinc excretion. The inverse association between urinary zinc excretion and uromodulin possibly points to an impaired tubular activity, which could partly account for zinc imbalance in CKD. These data suggest that zinc status is associated with renal function decline, but further studies elucidating the underlying mechanisms and the potential role of zinc supplements in CKD are needed.

Renal BOLD MRI in patients with chronic kidney disease: comparison of the semi-automated twelve layer concentric objects (TLCO) and manual ROI methods.

OBJECTIVE: Blood oxygenation level dependent (BOLD) MRI technique is used to evaluate changes in intra-renal oxygenation in chronic kidney disease (CKD). The purpose of this study was to evaluate if the novel twelve layer concentric objects (TLCO) method has advantages over the manually defined regions of interest (ROI) analysis. METHODS AND MATERIALS: Existing renal BOLD MRI data acquired before and after furosemide on a 3 T scanner from 41 CKD patients and 13 age matched healthy controls were analyzed using TLCO method and compared with previously reported ROI analysis. RESULTS: Regional R2* measurements were strongly correlated between the two methods, while ΔR2* was moderately correlated. Medullary R2* by ROI analysis showed higher values compared to R2*_Inner by TLCO, probably due to the contributions from the cortex to R2*_Inner. R2*_Slope and Δ(R2*_Slope), unique parameters based on the TLCO method provided the most significant differences between stage 3a CKD patients and controls and were correlated with eGFR. DISCUSSION: There was a high degree of agreement between the two methods in terms of regional R2* measurements and both methods did not show differences between moderate CKD patients and controls. However, R2*_Slope and Δ(R2*_Slope) showed the largest sensitivity in distinguishing CKD from controls.

Consensus-based technical recommendations for clinical translation of renal BOLD MRI.

Harmonization of acquisition and analysis protocols is an important step in the validation of BOLD MRI as a renal biomarker. This harmonization initiative provides technical recommendations based on a consensus report with the aim to move towards standardized protocols that facilitate clinical translation and comparison of data across sites. We used a recently published systematic review paper, which included a detailed summary of renal BOLD MRI technical parameters and areas of investigation in its supplementary material, as the starting point in developing the survey questionnaires for seeking consensus. Survey data were collected via the Delphi consensus process from 24 researchers on renal BOLD MRI exam preparation, data acquisition, data analysis, and interpretation. Consensus was defined as ≥ 75% unanimity in response. Among 31 survey questions, 14 achieved consensus resolution, 12 showed clear respondent preference (65-74% agreement), and 5 showed equal (50/50%) split in opinion among respondents. Recommendations for subject preparation, data acquisition, processing and reporting are given based on the survey results and review of the literature. These technical recommendations are aimed towards increased inter-site harmonization, a first step towards standardization of renal BOLD MRI protocols across sites. We expect this to be an iterative process updated dynamically based on progress in the field.

Reference values and sex differences in absolute and relative kidney size. A Swiss autopsy study.

BACKGROUND: Men have larger kidneys than women, but it is unclear whether gender remains an independent predictor of kidney size (expressed as weight or length) after correction for body size. We analysed autopsy data to assess whether relative renal length and weight (e.g. corrected for body weight, height or body surface area (BSA)) are also larger in men. Assuming that kidney size is associated with nephron number, opposite findings could partly explain why women are less prone to the development and progression of chronic kidney disease than men. METHODS: All forensic autopsies performed between 2009 and 2015 at the local university hospital of Geneva in individuals of European descent aged ≥18 years without a known history of diabetes and/or kidney disease were examined. Individuals with putrefied or severely injured bodies were excluded. Relative renal weight and length were respectively defined as renal weight divided by body weight or BSA and renal length divided by body height or BSA. RESULTS: A total of 635 autopsies (68.7% men) were included in the analysis. Left kidneys were on average 8 g heavier and 2 mm longer than right kidneys (both: p < 0.05). Absolute renal weight (165 ± 40 vs 122 ± 29 g) and length (12.0 ± 1.3 vs 11.4 ± 1.1 cm) were higher in men. Relative renal weight was also higher in men, but relative renal length was larger in women. In multivariable regression analysis, body height, body weight, the degree of blood congestion or depletion at autopsy and age were determinants of renal weight, whereas arterial hypertension and smoking were not. Percentile curves of renal weight and length according to sex and body height were constructed. CONCLUSION: Absolute and relative renal weights were both smaller in women. This is in line with recent studies stating that nephron numbers are also lower in women. Relative renal length was longer in women, suggesting that female kidneys have a more elongated shape. In comparison with older autopsy studies, renal weight appears to be stable over time.

[COVID-19 from the nephrologist's point of view]. / Vue sur le COVID-19 depuis la néphrologie.

During the actual pandemic of COVID-19, it has become clear that the virus causing this devastating disease, SARS-CoV2, targets not only the lungs but also other organs. In this article, we discuss the known or suspected interactions between the virus and the kidneys, as well as their clinical presentations. We also discuss how the pandemic has altered the activities of nephrologists and the logistics of a Swiss dialysis center.

Au cours de la pandémie de COVID-19, nombre de spécialistes se questionnent sur les interactions du virus avec différents tissus et organes au-delà de l'atteinte pulmonaire. Pour diverses raisons, l'effervescence a aussi gagné le néphrologue. Ce bref article présente les différents aspects de l'interaction virus-rein, l'impact de la pandémie sur les activités néphrologiques et tente de répondre à quelques questions d'actualité.