Effect of Blood Cadmium Level on Mortality in Patients Undergoing Maintenance Hemodialysis

Environmental PM2.5 Exposure: An Ignored Factor Associated with Blood Cadmium Level in Hemodialysis Patients

BACKGROUND

The negative impacts of particulate matter with an aerodynamic diameter of 2.5 μm or less (PM2.5) are well known. Patients undergoing maintenance hemodialysis (HD) have significantly higher blood cadmium levels (BCLs) than healthy individuals. As elemental cadmium can be found in the PM2.5 particle fraction, we conducted this study to assess the effect of environmental PM2.5 exposure and other clinical variables on BCLs in maintenance HD patients.

PATIENT AND METHODS

 This cross-sectional study included 754 hD patients who had previously participated in a BCL study. Demographic, hematological, biochemical and dialysis-related data were collected for analysis. For each patient, the mean PM2.5 concentrations in the living environment during the previous 12 and 24 months were recorded and analyzed.

RESULTS

Of all patients, the median BCL of was 0.36 µg/L (range: 0.21, 0.79 µg/L). The mean PM2.5 concentration was 28.45 ± 3.57 μg/m3 during the 12 months and 29.81 ± 3.47 μg/m3 during the 24 months, respectively. From a multivariate linear regression analysis, log BCL was positively associated with the mean PM2.5 concentration during the previous 12 and 24 months. In addition, log BCL was positively associated with the number of days with PM2.5 concentrations above the standard level during the previous 12 and 24 months. Moreover, according to the tertiles of days with a daily mean PM2.5 concentration above the normal limit in the previous 24 months, patients with the highest exposure days exhibited a significantly higher BCL than those in the other two patient groups.

CONCLUSION

Chronic environmental exposure to PM2.5 is significantly associated with BCLs in maintenance HD patients, and exposure to PM2.5-bound cadmium may contribute to the harmful effects on health in this population. Further studies are needed to confirm these observations and to explore the underlying mechanisms.

The general external exposome and the development or progression of chronic kidney disease: A systematic review and meta-analyses

The impact of environmental risk factors on chronic kidney disease (CKD) remains unclear. This systematic review aims to provide an overview of the literature on the association between the general external exposome and CKD development or progression. We searched MEDLINE and EMBASE for case-control or cohort studies, that investigated the association of the general external exposome with a change in eGFR or albuminuria, diagnosis or progression of CKD, or CKD-related mortality. The risk of bias of included studies was assessed using the Newcastle-Ottawa Scale. Summary effect estimates were calculated using random-effects meta-analyses. Most of the 66 included studies focused on air pollution (n = 33), e.g. particulate matter (PM) and nitric oxides (NOx), and heavy metals (n = 21) e.g. lead and cadmium. Few studies investigated chemicals (n = 7) or built environmental factors (n = 5). No articles on other environment factors such as noise, food supply, or urbanization were found. PM2.5 exposure was associated with an increased CKD and end-stage kidney disease incidence, but not with CKD-related mortality. There was mixed evidence regarding the association of NO2 and PM10 on CKD incidence. Exposure to heavy metals might be associated with an increased risk of adverse kidney outcomes, however, evidence was inconsistent. Studies on effects of chemicals or built environment on kidney outcomes were inconclusive. In conclusion, prolonged exposure to PM2.5 is associated with an increased risk of CKD incidence and progression to kidney failure. Current studies predominantly investigate the exposure to air pollution and heavy metals, whereas chemicals and the built environment remains understudied. Substantial heterogeneity and mixed evidence were found across studies. Therefore, long-term high-quality studies are needed to elucidate the impact of exposure to chemicals or other (built) environmental factors and CKD.

Assessing Cross-Sectional Association of Uremic Pruritus with Serum Heavy Metal Levels: A Single-Center Study

(1) Background: Uremic pruritus (UP) is a common and taxing symptom in patients on maintenance hemodialysis (MHD). We have previously shown that blood lead levels (BLLs) and blood aluminum levels (BALs) were separately positively associated with UP in MHD patients. We also found that blood cadmium levels (BCLs) were positively associated with all-cause mortality and cardiovascular-related mortality in MHD patients. We wondered whether there is any correlation between BCLs and UP after adjusting for BLLs and BALs. (2) Methods: Patients enrolled in this study were all from three hemodialysis (HD) centers at Chang Gung Memorial Hospital, Lin-Kou Medical Center, including both the Taipei and Taoyuan branches. Correlations between UP and BLLs, BALs, BCLs, and other clinical data were analyzed. (3) Results: Eight hundred and fifty-three patients were recruited. Univariate logistic regressions showed that diabetes mellitus, hepatitis B virus infection, hepatitis C virus infection, HD duration, hemodiafiltration, dialysis clearance of urea, normalized protein catabolic rate, non-anuria, serum albumin levels, log (intact-parathyroid hormone levels), total serum cholesterol levels, serum low-density lipoprotein levels, log (blood aluminum levels), and log (blood lead levels) were associated with UP. Although log BCLs were not significantly associated with UP (p = 0.136) in univariate analysis, we still included log BCLs in multivariate logistic regression to verify their effect on UP given that our aim in this study was to verify associations between serum heavy metals and UP. Multivariate logistic regressions showed that log BLLs (OR: 27.556, 95% CI: 10.912-69.587, p < 0.001) and log BALs (OR: 5.485, 95% CI: 2.985-10.079, p < 0.001) were positively associated with UP. The other logistic regression, which stratified BLLs and BALs into high and low BLLs and BALs, respectively, showed that high BLLs or high BALs (low BLLs and low BALs as reference) (OR: 3.760, 95% CI: 2.554-5.535, p < 0.001) and high BLLs and high BALs combined (low BLLs and low BALs as reference) (OR: 10.838, 95% CI: 5.381-21.828, p < 0.001) were positively correlated with UP. (4) Conclusions: BLLs and BALs were positively correlated with UP. BCLs were not correlated with UP. Clinicians should pay more attention to the environmental sources of lead and aluminum to prevent UP.

Associations of urinary and blood cadmium concentrations with all-cause mortality in US adults with chronic kidney disease: a prospective cohort study

Epidemiological evidence for the relationship between cadmium exposure and mortality in specific chronic kidney disease (CKD) populations remains scarce. We aimed to explore the relationships between cadmium concentrations in urine and blood and all-cause mortality among CKD patients in the USA. This cohort study was composed of 1825 CKD participants from the National Health and Nutrition Examination Survey (NHANES) (1999-2014) who were followed up to December 31, 2015. All-cause mortality was ascertained by matching the National Death Index (NDI) records. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality in relation to urinary and blood cadmium concentrations by Cox regression models. During an average follow-up period of 82 months, 576 CKD participants died. Compared with the lowest quartiles, HRs (95% CIs) for all-cause mortality associated with the fourth weighted quartiles of urinary and blood cadmium concentrations were 1.75 (1.28 to 2.39) and 1.59 (1.17 to 2.15), respectively. Furthermore, the HRs (95% CIs) for all-cause mortality per ln-transformed IQR increment in cadmium concentrations in urine (1.15 μg/g U_Cr) and blood (0.95 μg/L) were 1.40 (1.21 to 1.63) and 1.22 (1.07 to 1.40), respectively. Linear concentration-response relationships between urinary and blood cadmium concentrations and all-cause mortality were also found. Our findings suggested that increased cadmium concentrations in both urine and blood significantly contributed to enhanced mortality risk in CKD patients, thus highlighting that efforts to reduce cadmium exposure may reduce mortality risk in high-risk populations with CKD.

Do trace elements play a role in coronary artery calcification in hemodialysis patients?

PURPOSE

Abnormalities of trace elements have previously been linked to inflammatory processes in hemodialysis (HD) patients. We aimed to establish the trace element status of maintenance HD patients, to investigate the relationship between coronary artery calcification scores (CACs) and whole blood levels of trace elements.

METHODS

Patients undergoing HD in three times a week for > 6 months and age-and sex-matched controls were included from October 2015 to June 2016. Data were collected from patient files. All subjects' whole blood levels of trace elements were measured by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). CACs for patients were assessed by multi-detector computed tomography.

RESULTS

The 35 patients (male, 60%) with a mean age of 45.7 ± 10.4 years and 35 controls were included. HD patients showed significantly lower levels of selenium and uranium and higher cadmium (Cd), cobalt, lithium, manganese, nickel, lead, platinum, tin, strontium, and thallium levels compared to controls. Coronary artery calcification (CAC) was present in 21 patients (60%), and median CACs were 14.2 (IQR 0-149). Patients with CACs > median were significantly older, had a higher prevalence of hypertension and lower ALP levels than patients with CACs ≤ median. No significant differences in whole blood levels of trace elements were found between patients with CACs > median and patients with CACs ≤ median. A near significance was noted in median whole blood levels of Cd between these groups (P = 0.096). According to multivariate analysis, age was the only independent determinant for CAC development.

CONCLUSION

Age is independently associated with coronary vascular calcification. High Cd levels might play a role in CAC development in HD patients.

An omics approach to study trace metals in sera of hemodialysis patients treated with erythropoiesis stimulating agents

Hemodialysis (HD) represents a life-sustaining treatment for patients with end stage renal disease. However, it is associated with several complications, including anemia. Erythropoiesis stimulating agents (ESA) are often administered to HD patients with renal anemia, but a relevant proportion of them fail to respond to the therapy. Since trace metals are involved in several biological processes and their blood levels can be altered by hemodialysis, we study the possible association between serum trace metal concentrations and ratios with the administration and response to ESA. For this study, data and sample information of 110 HD patients were downloaded from the UC San-Diego Metabolomics Workbench public repository (PR000565). The blood serum levels (and ratios) of antimony, cadmium, copper, manganese, molybdenum, nickel, selenium, tin and zinc were studied applying an omics statistical approach. The Random Forest model was able to discriminate HD dependent patients treated and not treated with ESA, with an accuracy of 71.7% (95% CI 71.5-71.9%). Logistic regression analysis identifies alterations of Mn, Mo, Cd, Sn, and several of their ratios as characteristic of patients treated with ESA. Moreover, patients with scarce response to ESA showed to be characterized by reduced Mn to Ni and Mn to Sb ratios. In conclusion, our results show that trace metals, in particular manganese, play a role in the mechanisms underlying human response to ESA, and if further confirmed, the re-equilibration of their physiological levels could contribute to a better management of HD patients hopefully reducing their morbidity and mortality.

The effect of refined nursing intervention on patients undergoing maintenance hemodialysis in the hemodialysis center during the COVID-19 epidemic

Background

The outbreak of novel coronavirus pneumonia has exerted considerable psychological pressure on patients undergoing hemodialysis, resulting in unhealthy psychological emotions. Therefore, it is of great significance to carry out strict management and refined nursing intervention for patients undergoing maintenance hemodialysis during the prevention and control of novel coronavirus. This study aims to analyze and discuss the effect of clinical refined nursing intervention on patients undergoing maintenance hemodialysis during the coronavirus disease 2019 (COVID-19) epidemic.

Methods

This was a prospective cohort study. In this study, we used the Symptom Checklist-90 (SCL-90) or the Chinese adult SCL-90 norm to conduct nursing interventions for patients undergoing maintenance hemodialysis to investigate the effect of clinical refined nursing intervention on patients undergoing maintenance hemodialysis during the COVID-19 epidemic.

Results

The scores for all the factors of SCL-90 of patients undergoing maintenance hemodialysis were higher than those of the Chinese SCL-90, and patients with a single factor score ≥ 2 had a higher level of depression and anxiety, with extremely significant difference (p < 0.01). The depression and anxiety of the patients were reduced after the intervention, and there was a statistical difference. Among the 172 patients, the results of both nucleic acid tests were negative.

Conclusion

During the COVID-19 epidemic, providing patients undergoing maintenance hemodialysis with refined nursing intervention can regulate negative emotions, reduce related complications, improve their quality of life, and improve the nurse–patient relationship.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12912-021-00584-5.

MicroRNA-101 inhibits cadmium-induced angiogenesis by targeting cyclooxygenase-2 in primary human umbilical vein endothelial cells

Exposure to toxic metal contaminants, such as cadmium compounds (Cd²⁺), has been shown to induce adverse effects on various organs and tissues. In particular, blood vessels are severely impacted by Cd²⁺ exposure, which may lead to cardiovascular diseases (CVDs). According to previous studies, CVDs are associated with increased cyclooxygenase 2 (COX-2) levels. However, the mechanisms by which CdCl₂-induced COX-2 overexpression leads to cardiovascular dysfunction remain unclear. Herein, we show that the relative gene expressions of VEGF and PTGS2 (COX-2 encoding gene) are positively correlated in CVDs patients. Moreover, we demonstrate that the in vitro administration of CdCl₂ induces cytotoxicity and endoplasmic reticulum (ER) stress in primary human umbilical vein endothelial cells (HUVECs). The induction of ER stress and the overexpression of COX-2 in CdCl₂-treated cells alters the protein level of vascular endothelial growth factor (VEGF), resulting in abnormal angiogenesis and increased cytotoxicity. At the pre-transcription level, the inhibition of ER stress by siGRP78 (a key mediator of ER stress) can restore normal angiogenesis in the CdCl₂-exposed cells. Meanwhile, at the transcription level, the adverse effects of CdCl₂ exposure may be reversed via genetic modification with siRNA (siPTGS2) or by using phytochemical inhibitors (parthenolide, PN) of COX-2. Finally, at the post-transcription level, COX-2 expression may be restricted by the binding of microRNA-101 (miR-101) to the 3'-UTR of PTGS2 mRNA. The use of mimic miR-101 (mi101) to induce the expression of miR-101 eventually leads to reduced COX-2 protein levels, relieved ER stress, and less abnormal angiogenesis and cytotoxicity of CdCl₂-exposed primary HUVECs. Overall, our results suggest that CdCl₂-induced abnormal angiogenesis is mediated by miR-101/COX-2/VEGF-axis-dependent ER stress, and that cardiovascular dysfunction may be controlled by manipulating COX-2 at the pre-transcription, transcription, and post-transcription levels.

Association between trace element concentrations and anemia in patients with chronic kidney disease: a cross-sectional population-based study

Anemia is common in chronic kidney disease (CKD) and may be affected by trace element concentrations. While the concentrations of trace elements are known to be altered in CKD, the relationship between trace element and hemoglobin concentrations has not been systematically investigated in a large cohort. This study aims to examine associations between trace element concentrations and anemia in patients with CKD. Data from the National Health and Nutrition Examination Survey collected from 2011 to 2014 were used for this analysis. The participants who were more than 20 years old were included. A total of 3057 participants were included; the final cohort was divided into two groups based on CKD status. The concentrations of hemoglobin, iron, zinc, and manganese were significantly lower in participants with than without CKD (all p<0.05). Multivariate analyses showed that in patients without CKD, hemoglobin concentrations correlated positively with iron, zinc, and cadmium (β=0.005, 0.009, and 0.33, respectively), but correlated negatively with copper levels (β=-0.002). In patients with CKD, hemoglobin concentrations correlated positively with cadmium and selenium, but negatively with copper levels (β=0.57, 0.007, and -0.008, respectively). The serum iron concentration was found to correlate positively with zinc, cadmium, and selenium, but negatively with copper and manganese concentrations in the total study population (all p<0.05). The associations between serum concentrations of trace elements and hemoglobin differ between patients with and without CKD. Further investigations are warranted to determine whether patients with CKD have distinct trace element requirements.

Hepatocellular carcinoma in hemodialysis patients

We investigated the rates and predictors of mortality in hepatocellular carcinoma (HCC) patients who were or were not undergoing long-term hemodialysis. The participants in this retrospective observational study were 1298 HCC patients (60.0 ± 12.1 years old, 72% male), of whom 172 were undergoing hemodialysis and 1126 were not. HCC patients on hemodialysis exhibited a higher hepatitis C virus carrier rate (49.4% versus 39.3%, P = 0.012), lower hepatitis B virus carrier rate (37.2% versus 58.3%, P < 0.001) and lower hepatitis B or C virus carrier rate (77.9% versus 89.3%, P < 0.001) than those not on hemodialysis. Serum alkaline phosphatase levels were higher in the hemodialysis than non-hemodialysis group (162.8 ± 141.1 u/l versus 124.6 ± 102.5 u/l, P < 0.001). By the end of the analysis, 32.0% of HCC patients on hemodialysis and 28.0% of those not on hemodialysis had died. Kaplan-Meier analysis confirmed that cumulative survival was poorer in HCC patients on hemodialysis (P = 0.004). In a multivariate Cox regression model, hemodialysis (P < 0.001), older age (P < 0.001) and advanced tumor stages (P < 0.001) were found to be risk factors for mortality. HCC patients on hemodialysis had a 2.036-fold greater chance of death than HCC patients not on hemodialysis. Prospective studies with longer follow-ups and larger samples are warranted.

Urinary cadmium levels predict mortality of patients with acute heart failure

BACKGROUND

Acute heart failure (AHF) is a serious condition that is associated with increased mortality in critically ill patients. Previous studies indicated that environmental exposure to cadmium increases mortality of general populations. However, the relationship of cadmium exposure and mortality is unclear for AHF patients.

MATERIALS AND METHODS

A total of 153 patients with AHF in intensive care units (ICUs) met the inclusion criteria and were followed up for 6 months. Demographic data, AHF etiology, hematological and biochemical data, and hospital mortality were recorded. The scores of two predictive systems (Sequential Organ Failure Assessment [SOFA], Acute Physiology and Chronic Health Evaluation II [APACHE II]) for mortality in critically ill patients were calculated, and urinary cadmium levels were recorded.

RESULTS

At the end of the follow-up period, the mortality rate was 24.8%. The survivors (n=115) had higher urinary cadmium levels on day 1 (D1UCd) of ICU admission than non-survivors (n=38). A multiple linear regression analysis revealed a positive correlation between D1UCd and acute kidney injury, but a negative correlation between D1UCd and the level of serum albumin. A multivariate Cox analysis indicated that D1UCd was an independent predictor of mortality in AHF patients. For each increment of 1 μg of D1UCd, the hazard ratio for ICU mortality was 1.20 (95% confidence interval [CI]: 1.09-1.32, P<0.001). The area under the receiver operating characteristic curve for D1UCd was 0.84 (95% CI: 0.78-0.91), better than the values for the SOFA and APACHE II systems.

CONCLUSION

The D1UCd may serve as a single predictor of hospital mortality for AHF patients in the ICU. Because of the high mortality and smaller sample size, more investigations are required to confirm these observations and elucidate the underlying mechanisms.

Association Between Blood Cadmium Levels and Mortality in Peritoneal Dialysis

The negative impact of environmental exposure of cadmium has been well established in the general population. However, the effect of cadmium exposure in chronic peritoneal dialysis (PD) patients remains uncertain.A total of 306 chronic PD patients were included in this 36-month observational study. Patients were stratified into 3 groups by the tertile of baseline blood cadmium levels (BCLs): high (>0.244 μg/L, n = 101), middle (0.130-0.244 μg/L, n = 102), and low (<0.130 μg/L, n = 103) for cross-sectional analyses. Mortality rates and cause of death were recorded for longitudinal analyses.Patients in the high-BCL group were older, more likely to have diabetes mellitus, had lower levels of serum albumin and lower percentage of lean body mass than patients in the low-BCL group. A multivariate logistic regression analysis revealed that logarithmic transformed BCL was independently associated with a higher risk of low turnover bone disease (odds ratio = 3.8, P = 0.005). At the end of the 36-month follow-up, 66 (21.6%) patients died. Mortality rates increased with higher BCLs (P for trend = 0.005). A Cox multivariate analysis showed that, using the low-BCL group as the reference, the high-BCL group had increased hazard ratios (HR) for all-cause mortality in chronic PD patients after adjusting for related variables (HR = 2.469, 95% confidence interval = 1.078-5.650, P = 0.043).In conclusion, BCL showed significant association with malnutrition and low turnover bone disease in chronic PD patients. Furthermore, BCL is an important determinant of mortality. Our findings suggest that avoiding environmental exposure to cadmium as much as possible is warranted in chronic PD patients.