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Rationale & objective High anion gap acidosis frequently develops in patients with advanced chronic kidney disease (CKD) and might be involved in kidney injury. Its impact on kidney outcomes, however, has not been well studied. We sought to examine the association between time-updated anion gap and the risk of kidney failure with replacement therapy (KFRT) among patients with advanced CKD. Study design Retrospective cohort study. Setting & participants 1,168 patients with CKD glomerular filtration rate categories 3b-5 (G3b-G5) who had available data on anion gap. Exposure High time-updated anion gap defined as values ≥ 9.2 (top 25th percentile). Outcome KFRT and death. Analytical approach Marginal structural models were fit to characterize the association between anion gap and study outcomes while accounting for potential time-dependent confounding. Results The mean baseline estimated glomerular filtration rate (eGFR) of the study participants was 28 mL/min/1.73 m2. Over a median follow-up period of 3.1 years, 317 patients progressed to KFRT (7.5 per 100 patient-years), and 146 died (3.5 per 100 patient-years). In the marginal structural models, a high anion gap was associated with a higher rate of KFRT (HR, 3.04 [95% CI, 1.94-4.75]; P Limitations Observational study design and selection bias due clinical indications for measuring anion gap. Conclusions Among patients with advanced CKD, high anion gap was associated with an increased risk of progression to KFRT and death.

Aims The prognostic significance of renal function variability has not been fully elucidated in heart failure (HF). This multicentre, prospective cohort study aimed to evaluate the usefulness of visit‐to‐visit variability in estimated glomerular filtration rate (eGFR) for predicting patients' outcomes in a real‐world HF population. Methods A total of 564 patients who had survived HF hospitalization were randomly assigned with a 2:1 ratio to derivation and validation cohorts, and they were then followed after discharge. Using the data for 6 months after discharge, each patient's visit‐to‐visit eGFR variability (EGV) was estimated. In the derivation cohort, Cox regression analyses were performed to assess the association of EGV with a subsequent composite event (death and HF hospitalization). In the validation cohort, the predictive performance was compared among Cox regression models with EGV, those with B‐type natriuretic peptide (BNP) and those with eGFR. Results In the derivation cohort (376 patients), median age, left ventricular ejection fraction (LVEF), BNP and eGFR at discharge were 72 years, 53.3%, 134.8 pg/mL and 58.7 mL/min/1.73 m2, respectively. During a median follow‐up of 2.2 years, higher EGV was associated with an increased risk of the composite event (adjusted hazard ratio [per standard deviation increase in log‐transformed EGV], 1.5; 95% confidence interval, 1.1–2.0). A similar finding was observed in a stratified analysis by LVEF. In the validation cohort (188 patients), better model fit, discrimination, reclassification and calibration were observed for EGV than for 6‐month averaged BNP or eGFR for predicting the composite event when added to HF risk prediction models. Adding EGV to models with BNP or eGFR improved model discrimination and reclassification. Conclusions EGV predicts HF outcomes regardless of LVEF. Risk prediction models with EGV have good performance in real‐world HF patients. The study findings highlight the clinical importance of observing visit‐to‐visit fluctuations in renal function in this population.

Hemoglobin levels usually decline before dialysis initiation. The influence of overhydration on anemia progression and iron sequestration is poorly documented. Furthermore, clinical implications of anemia at dialysis initiation remain to be elucidated. This multicenter retrospective cohort study enrolled incident dialysis patients. The patients were stratified by tertiles of overhydration rate (OH-R) defined by (BW − DW)/DW*100 (BW: body weight just before dialysis initiation, DW: dry weight). Time courses (6 months before, to 1 month after, dialysis initiation) of hemoglobin, C-reactive protein (CRP), and iron sequestration index (ISI) were examined using mixed effects models. We used Cox models to identify anemia parameters predicting subsequent cardiovascular disease (CVD). Among the 905 enrolled patients, hemoglobin levels gradually decreased before dialysis initiation and rapidly increased thereafter. An inverse V-shaped time course was observed for CRP and ISI with an increase during dialysis initiation. Patients with a higher OH-R showed lower hemoglobin levels along with higher CRP and ISI levels before dialysis initiation. Mean corpuscular hemoglobin concentration (MCHC) was more stable before dialysis initiation than were mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). Low MCHC (

Background: Real-world evidence about mineralocorticoid receptor antagonist (MRA) use has been limited in chronic kidney disease, particularly regarding its association with hard renal outcomes. Methods: In this retrospective cohort study, adult chronic kidney disease outpatients referred to the department of nephrology at an academic hospital between January 2005 and December 2018 were analyzed. The main inclusion criteria were estimated glomerular filtration rate ≥10 and 2 and follow-up ≥90 days. The exposure of interest was MRA use, defined as the administration of spironolactone, eplerenone, or potassium canrenoate. The primary outcome was renal replacement therapy initiation, defined as the initiation of chronic hemodialysis, peritoneal dialysis, or kidney transplantation. A marginal structural model using inverse probability of weighting was applied to account for potential time-varying confounders. Results: Among a total of 3195 patients, the median age and estimated glomerular filtration rate at baseline were 66 years and 38.4 mL/min per 1.73 m 2 , respectively. During follow-up (median, 5.9 years), 770 patients received MRAs, 211 died, and 478 started renal replacement therapy. In an inverse probability of weighting-weighted pooled logistic regression model, MRA use was significantly associated with a 28%-lower rate of renal replacement therapy initiation (hazard ratio, 0.72 [95% CI, 0.53–0.98]). The association between MRA use and renal replacement therapy initiation was dose-dependent ( P for trend 5.5 mEq/L) was somewhat higher in MRA users but not significant (hazard ratio, 1.14 [95% CI, 0.88–1.48]). Conclusions: MRA users showed a better renal prognosis across various chronic kidney disease subgroups in a real-world chronic kidney disease population.

Background Developing strategies for managing coronary artery calcification (CAC) in patients with CKD is an important clinical challenge. Experimental studies have demonstrated that magnesium inhibits vascular calcification, whereas the uremic toxin indoxyl sulfate aggravates it. Methods To assess the efficacy of magnesium oxide (MgO) and/or the oral carbon adsorbent AST-120 for slowing CAC progression in CKD, we conducted a 2-year, open-label, randomized, controlled trial, enrolling patients with stage 3−4 CKD with risk factors for CAC (diabetes mellitus, history of cardiovascular disease, high LDL cholesterol, or smoking). Using a two-by-two factorial design, we randomly assigned patients to an MgO group or a control group, and to an AST-120 group or a control group. The primary outcome was percentage change in CAC score. Results We terminated the study prematurely after an interim analysis with the first 125 enrolled patients (of whom 96 completed the study) showed that the median change in CAC score was significantly smaller for MgO versus control (11.3% versus 39.5%). The proportion of patients with an annualized percentage change in CAC score of ≥15% was also significantly lower for MgO compared with control (23.9% versus 62.0%). However, MgO did not suppress the progression of thoracic aorta calcification. The MgO group’s dropout rate was higher than that of the control group (27% versus 17%), primarily due to diarrhea. The percentage change in CAC score did not differ significantly between the AST-120 and control groups. Conclusions MgO, but not AST-120, appears to be effective in slowing CAC progression. Larger-scale trials are warranted to confirm these findings.

The prognostic value of electrocardiograms (ECGs) has been reported in predialysis patients but not in incident hemodialysis patients with overhydration and electrolyte disturbances, both of which potentially affect ECG results. We performed a retrospective multicenter cohort study involving incident hemodialysis patients and examined whether ECG parameters immediately before hemodialysis initiation can predict subsequent cardiovascular disease (CVD) using Cox proportional hazards models. We explored potential effect modifications by several electrolytes on the predictive power of ECG abnormalities. Among the 618 enrolled patients, 16%, 10%, 46%, and 22% showed a PR interval ≥ 200 ms, QRS interval ≥120 ms, QTc interval ≥ 450/460 ms (male/female), and left ventricular hypertrophy (LVH) by voltage criteria, respectively. Over a median 3-year follow-up, 19% and 16% of the patients developed atherosclerotic and nonatherosclerotic CVD, respectively. The Cox regression model results revealed that the sum of the number of abnormalities in PR, QRS, and QT intervals was a significant risk factor for nonatherosclerotic CVD (hazard ratios (HRs) [95% confidence interval (CI)]: 1.58 [1.24-2.01] per number of abnormalities). The predictive value of LVH for atherosclerotic CVD was attenuated over time. At up to 36 months, although the proportional hazards assumption was met, LVH was significantly associated with atherosclerotic CVD (HR [95% CI]: 1.89 [1.15-3.11]). The adjusted HR was particularly high (HR [95% CI]: 4.02 [1.68-9.60]) among patients who were in the lowest tertile of serum magnesium levels (P for interaction = 0.04). PR, QRS, and QT prolongation additively predicted nonatherosclerotic CVD, while LVH predicted atherosclerotic CVD in the short term.

Lower corrected calcium (cCa) levels are associated with a better prognosis among incident dialysis patients. However, cCa frequently overestimates ionized calcium (iCa) levels. The prognostic importance of the true calcium status defined by iCa remains to be revealed. We conducted a retrospective cohort study of incident hemodialysis patients. We collected data of iCa levels immediately before the first dialysis. We divided patients into three categories: apparent hypocalcemia (low iCa

We present a case of Dent disease caused by a novel intronic mutation, 1348-1G>A, of the chloride voltage-gated channel 5 (CLCN5) gene. Cultured proximal tubule cells obtained from the patient showed impaired acidification of the endosome and/or lysosome, indicating that the 1348-1G>A mutation was indeed the cause of Dent disease. Although the prevalence of osteomalacia in Dent disease is low in Japan, several factors-including poor medication adherence-caused severe osteomalacia in the current case. Oral supplementation with calcium and native/active vitamin D therapy, with careful attention to medication adherence, led to the improvement of the patient's bone status.

Several experimental studies have shown that fibroblast growth factor 23 (FGF23) induces left ventricular hypertrophy (LVH). However, the opposite directional relationship, namely a potential effect of LVH on FGF23, remains uncertain. Here we evaluated the effects of LVH on FGF23 using cardiomyocyte-specific calcineurin A transgenic mice. At six weeks, these mice showed severe LVH, with elevated levels of serum intact FGF23. FGF23 levels were elevated in cardiomyocytes, but not osteocytes, of the transgenic animals. Moreover, transverse aortic constriction also upregulated myocardial FGF23 expression in wild type mice. The promoter region of the FGF23 gene contains two putative nuclear factors of activated T cells (NFAT)-binding sites, with NFAT1 activating the promoter in a proximal NFAT-binding site dependent manner. Neither serum, urinary, or fractional excretion values of calcium and phosphate nor serum levels of 1,25(OH)2 vitamin D were different between wild type and transgenic mice. Moreover, the renal expression of FGF receptors and α-Klotho was comparable. However, plasma levels of antidiuretic hormone were significantly increased in the transgenic mice, and aquaporin-2 immunohistochemical staining was mainly positive in the apical membrane of the collecting duct, compared to a primarily cytoplasmic staining in wild type mice. Real-time PCR analyses of kidney CYP27B1 and CYP24A1 expression in wild type mice showed that exogenous antidiuretic hormone blocked FGF23's actions on these vitamin D activating or inactivating enzymes. Finally, the renal resistance of transgenic mice to FGF23 was partly overcome by tolvaptan. Thus, LVH in transgenic mice is associated with an increase in myocardial and serum intact FGF23, with the kidneys being protected against FGF23 excess by elevated antidiuretic hormone levels.

Background and objectives Circulating levels of anions that bind to magnesium and calcium are often altered in patients with CKD. However, it is unknown how these alterations affect the ionized fraction of magnesium and calcium. Design, setting, participants, & measurements This cross-sectional study involved patients on maintenance hemodialysis and patients not on dialysis who visited the outpatient department of nephrology. We collected whole-blood samples to measure ionized magnesium and calcium concentrations. Adjusted anion gap was calculated as an integrative index of unmeasured anions. Results A total of 118 patients on hemodialysis and 112 patients not on dialysis were included. Although the prevalence of hypermagnesemia defined by total magnesium was much higher in patients on hemodialysis than in patients not on dialysis (69% versus 12%; P Conclusions Anions that accumulate in patients on hemodialysis contribute to the lower ionized fraction of magnesium and calcium. Equations that incorporate the anion gap provide better predictions of ionized magnesium and calcium in patients on hemodialysis.

Phosphate/calcium homeostasis is crucial for health maintenance. Lithocholic acid, a bile acid produced by intestinal bacteria, is an agonist of vitamin D receptor. However, its effects on phosphate/calcium homeostasis remain unclear. Here, we demonstrated that lithocholic acid increases intestinal phosphate/calcium absorption in an enterocyte vitamin D receptor-dependent manner. Lithocholic acid was found to increase serum phosphate/calcium levels and thus to exacerbate vascular calcification in animals with chronic kidney disease. Lithocholic acid did not affect levels of intestinal sodium-dependent phosphate transport protein 2b, Pi transporter-1, -2, or transient receptor potential vanilloid subfamily member 6. Everted gut sac analyses demonstrated that lithocholic acid increased phosphate/calcium absorption in a transcellular pathway-independent manner. Lithocholic acid suppressed intestinal mucosal claudin 3 and occludin in wild-type mice, but not in vitamin D receptor knockout mice. Everted gut sacs of claudin 3 knockout mice showed an increased permeability for phosphate, but not calcium. In patients with chronic kidney disease, serum 1,25(OH)2 vitamin D levels are decreased, probably as an intrinsic adjustment to reduce phosphate/calcium burden. In contrast, serum and fecal lithocholic acid levels and fecal levels of bile acid 7α-dehydratase, a rate-limiting enzyme involved in lithocholic acid production, were not downregulated. The effects of lithocholic acid were eliminated by bile acid adsorptive resin in mice. Thus, lithocholic acid and claudin 3 may represent novel therapeutic targets for reducing phosphate burden.

A 71-year-old woman with polymyositis presenting with left thigh pain and an intermittent fever was admitted to Osaka Rosai Hospital. We initially diagnosed that her pain and fever were caused by a soft tissue infection because her polymyositis was controlled. She did not respond to various antibiotic therapies. Chest computed tomography demonstrated miliary tuberculosis (TB). Ziehl-Neelsen staining of liver biopsy specimens revealed epithelioid cell granuloma and acid-fast bacilli. Therefore, we finally diagnosed the lesion as TB fasciitis that improved with anti-TB drug therapy. The atypical presentation of TB fasciitis demonstrates the clinical importance of eliminating TB infections in immunocompromised hosts.

Background Serum chloride (Cl) levels confer better prognostic value than serum sodium (Na) levels among patients with heart failure. Little is known about the relationship between serum Cl levels and clinical outcomes among patients with chronic kidney disease (CKD). Methods This was a retrospective cohort study enrolling patients with Stages G3–G5 CKD who visited the nephrology outpatient department of Osaka University Hospital from April 2005 to December 2014. The main exposure was time-varying serum Cl levels categorized as quartiles. The study outcome was a composite of all-cause death and cardiovascular events. Results A total of 2661 patients with CKD were included in the analysis. During a median follow-up of 4.0 years, 284 deaths and 416 cardiovascular events occurred. Compared with patients in the third Cl quartile, those in the first Cl quartile showed a significantly higher risk of the outcome after adjustment for demographics and clinical factors including time-varying serum Na, serum albumin and bicarbonate levels, and use of diuretics and sodium bicarbonate [hazard ratio (HR) 2.13; 95% confidence interval (CI) 1.20–3.81; P = 0.01] and, additionally, anion gap (HR 2.13; 95% CI 1.26–3.57; P = 0.004). Adding serum Cl levels, but not serum Na levels, to the multivariable model significantly improved net reclassification index (0.335; P Conclusions Lower serum Cl levels are an independent predictor of death and cardiovascular events. The incremental prognostic value of Cl was superior to that of Na in patients with CKD.

BackgroundHypomagnesemia (Hypo-Mg) predicts mortality and chronic kidney disease (CKD) progression. However, in CKD, its prevalence, kidney-intrinsic risk factors, and the effectiveness of oral magnesium (Mg) therapy on serum Mg levels is uncertain.MethodsIn a cross-sectional study enrolling pre-dialysis outpatients with CKD, the prevalence of electrolyte abnormalities (Mg, sodium, potassium, calcium and phosphorus) was compared. In an open-label randomized controlled trial (RCT), we randomly assigned CKD patients to either the magnesium oxide (MgO) or control arm. The outcome was serum Mg levels at 1 year.ResultsIn 5126 patients, Hypo-Mg was the most common electrolyte abnormality (14.7%) with similar prevalence across stages of CKD. Positive proteinuria was a risk factor of Hypo-Mg (odds ratio 2.2; 95% confidence interval 1.2–4.0). However, stratifying the analyses by diabetes mellitus (DM), it was not significant in DM (Pinteraction = 0.04). We enrolled 114 patients in the RCT. Baseline analyses showed that higher proteinuria was associated with higher fractional excretion of Mg. This relationship between proteinuria and renal Mg wasting was mediated by urinary tubular markers in mediation analyses. In the MgO arm, higher proteinuria or tubular markers predicted a significantly lower 1-year increase in serum Mg. In patients with a urinary protein-to-creatinine ratio (uPCR) ConclusionsProteinuria leads to renal Mg wasting through tubular injuries, which explains the high prevalence of Hypo-Mg in CKD.

Higher red cell distribution width (RDW) has been reported to predict mortality among patients with various diseases, including chronic kidney disease (CKD). However, whether RDW is associated with renal outcome remains unclear. We investigated the relationship between RDW and renal outcome in patients with non-dialysis-dependent CKD (NDD-CKD). This prospective, observational study of patients with CKD was conducted at a single nephrology department. First, we performed regression analyses for the decline in estimated glomerular filtration rate (eGFR) during the first 3 months of observation to determine its short-term association with RDW. Next, we categorized baseline RDW into two groups by its median (13.5%) and performed Cox regression analyses to investigate whether higher RDW was an independent predictor of renal outcomes defined as a composite of the initiation of dialysis and doubling of the serum creatinine concentration. Furthermore, we repeated the analyses to confirm whether the transition of the RDW category during the first 3 months would also predict renal outcomes. We enrolled 703 patients. Baseline RDW showed a non-linear association with the eGFR decline during the first 3 months, with a greater negative correlation at the lower end of the RDW distribution. Over a median follow-up of 1.8 years, 178 patients (25.3%) reached the renal endpoint. Multivariable Cox regression analyses showed that patients with higher RDW had a higher risk of developing renal outcomes (adjusted hazard ratio [HR]: 1.47, 95% confidence interval [CI]: 1.05-2.07) than did those with lower RDW. Furthermore, patients with sustained, higher RDW demonstrated a significantly higher risk than did those with consistently lower RDW (adjusted HR: 1.65, 95% CI: 1.02-2.67). In conclusion, higher RDW was independently associated with worse renal outcome in patients with NDD-CKD. RDW could be an additional prognostic marker of the progression of CKD.

Protein carbamylation is a posttranslational modification that can occur non-enzymatically in the presence of high concentrations of urea. Although carbamylation is recognized as a prognostic biomarker, the contribution of protein carbamylation to organ dysfunction remains uncertain. Because vascular calcification is common under carbamylation-prone situations, we investigated the effects of carbamylation on this pathologic condition. Protein carbamylation exacerbated the calcification of human vascular smooth muscle cells (hVSMCs) by suppressing the expression of ectonucleotide pyrophosphate/phosphodiesterase 1 (ENPP1), a key enzyme in the generation of pyrophosphate, which is a potent inhibitor of ectopic calcification. Several mitochondrial proteins were carbamylated, although ENPP1 itself was not identified as a carbamylated protein. Rather, protein carbamylation reduced mitochondrial membrane potential and exaggerated mitochondria-derived oxidative stress, which down-regulated ENPP1. The effects of carbamylation on ectopic calcification were abolished in hVSMCs by ENPP1 knockdown, in mitochondrial-DNA-depleted hVSMCs, and in hVSMCs treated with a mitochondria-targeted superoxide scavenger. We also evaluated the carbamylation effects using ex vivo and in vivo models. The tunica media of a patient with end-stage renal disease was carbamylated. Thus, our findings have uncovered a previously unrecognized aspect of uremia-related vascular pathology.

Background The Agatston score, commonly used to quantify coronary artery calcification (CAC), is determined by the plaque area and density. Despite an excellent predictability of the Agatston score for cardiovascular events, the density of CAC has never been studied in patients with pre-dialysis chronic kidney disease (CKD). This study aimed to analyze the CAC density and its association with serum mineral levels in CKD. Methods We enrolled patients with pre-dialysis CKD who had diabetes mellitus, prior cardiovascular disease history, elevated low-density lipoprotein cholesterol levels, or smoking history. The average CAC density was calculated by dividing the Agatston score by the total area of CAC. Results The mean estimated glomerular filtration rate (eGFR) of 109 enrolled patients was 35.7 mL/min/1.73 m2. The correlation of the Agatston score with density was much weaker than that with the total area (R2 = 0.19, P < 0.001; and R2 = 0.99, P < 0.001, respectively). Multivariate analyses showed that serum magnesium level was inversely associated with the density, but not with the total area, after adjustment for demographics and clinical factors related to malnutrition-inflammation-atherosclerosis syndrome and mineral and bone disorders including fibroblast growth factor 23 (P = 0.006). This inverse association was pronounced among patients with higher serum phosphate levels (P for interaction = 0.02). Conclusion CAC density was inversely associated with serum magnesium levels, particularly in patients with higher serum phosphate levels.