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

Exploring Associations and Mediating Factors between Multiple Trace Metals with Anemia in US Adults: Insight from NHANES 2017-2020

BACKGROUND

Anemia significantly contributes to the global disease burden, with its incidence potentially influenced by the trace metal content within the body.

OBJECTIVE

This study aims to examine the associations between trace metals and anemia risk, with a particular focus on investigating the potential mediating roles of iron status and inflammation in these associations.

METHODS

Five trace metals (Ni, Co, Mn, Se, and Mo) were examined in 1274 US adults, utilizing data from the National Health and Nutrition Examination Survey (NHANES) 2017-2020. The individual and combined effects of these metals on anemia were assessed using logistic regression, quantile g-computation (QGC), and Bayesian kernel machine regression (BKMR). A sex-stratified analysis was conducted to discern any gender-specific susceptibilities. Additionally, mediation analysis was employed to explore the potential mediating roles of iron status and inflammation in the associations between these metals and anemia.

RESULTS

Increased risks of anemia were positively associated with Co and Ni levels but negatively correlated with Se and Mn levels (all with p < 0.05). The trace metal mixture was negatively associated with anemia, with the highest weights of Co and Se in different directions in both the QGC and BKMR models. In the sex-specific analysis, we observed less pronounced protective effects from trace metals in females. Moreover, the mediating proportion of the iron status and inflammation in these relationships ranged from 10.29% to 58.18%.

CONCLUSION

Our findings suggest that the trace element mixture was associated with decreased anemia risk, among which Se was a protective factor while Co was a risk factor, and females were more susceptible. The effects of these trace metals on anemia may be mediated by the iron status and inflammation.

Association of dietary manganese intake with new-onset chronic kidney disease in participants with diabetes

BACKGROUND

We explored the association of dietary manganese (Mn) with new-onset chronic kidney disease (CKD) in participants with diabetes on different glycemia control status and potential mechanisms.

METHODS

The study included 7248 adults with diabetes from the UK Biobank who had complete dietary data and were free of CKD at baseline. Dietary information was collected by the online 24-h diet recall questionnaires. The primary outcome was new-onset CKD.

RESULTS

565 (7.8 %) participants developed new-onset CKD during a median follow-up of 11.96 years. Overall, there was a significantly inverse relationship of dietary Mn intake with new-onset CKD in individuals with diabetes at glycated hemoglobin (HbA1c) ≥6.5 % (per SD increment, HR [95%CI]: 0.79 [0.68-0.91]), but not in people with diabetes at HbA1c <6.5 % (per SD increment, HR [95%CI]: 1.07 [0.90-1.29]; P for interaction = 0.004). In individuals with diabetes at HbA1c ≥6.5 %, body mass index and waist circumference significantly mediated the association between dietary Mn intake and new-onset CKD, with mediated proportions of 17.5 % and 17.4 %, respectively.

CONCLUSIONS

Higher dietary Mn intake was significantly associated with a lower new-onset CKD risk in participants with diabetes at poor glycemic control status. The inverse association was mainly mediated by obesity. If further confirmed, our findings underscore the importance of maintaining adequate dietary Mn intake for the primary prevention of new-onset CKD in patients with diabetes, especially those with poor glycemic control.

Association between the serum zinc level and nutritional status represented by the geriatric nutritional Rrisk index

BACKGROUND

Although it is widely known that patients with chronic kidney disease (CKD) can develop zinc deficiency, in our previous analysis, the estimated glomerular filtration rate (eGFR) was not independently associated with the serum zinc level. Thus, a post hoc analysis was conducted to investigate the involvement of nutritional status.

METHODS

A total of 655 subjects not on dialysis (402 males; mean age, 57 ± 18 years) who underwent serum zinc level measurements at Jikei University Hospital between April 2018 and March 2019 were selected using the Standardized Structured Medical Information eXchange2 (SS-MIX2) system. In addition, anthropometric data and the Geriatric Nutritional Risk Index (GNRI) representing nutritional status were obtained, and the relationship between the serum zinc level and nutritional status was investigated by multiple regression analysis.

RESULTS

The serum albumin level and the GNRI were lower in the zinc-deficiency group, and both were positively associated with the serum zinc level (rho = 0.44, P < 0.01 and rho = 0.44, P < 0.01, respectively). On multiple regression analysis, the GNRI (t = 3.09, P < 0.01) and serum albumin level (t = 4.75, P < 0.01) were independently associated with the serum zinc level. Although a higher eGFR was associated with a higher serum zinc level, this association disappeared on multivariate analysis.

CONCLUSION

In this post hoc analysis, the GNRI, as well as the serum albumin level, were correlated with the serum zinc level, indicating that nutritional status is an important determinant of the zinc level. Further investigations are needed to clarify the effects of nutritional status and kidney function on zinc deficiency.

Synergistic impact of co-exposures to whole blood metals on chronic kidney disease in general US adults: a cross‑sectional study of the National Health and Nutrition Examination Survey 2011-2020

The impact of exposure to metals on chronic kidney disease (CKD) has only been investigated in two-way or single metal interactions in previous studies. We investigated the associations between five single metals in blood and their mixed exposure and CKD by using the machine learning approach. Relevant data were extracted from the National Health and Nutrition Examination Survey (NHANES 2011-2020), and the level of five metals in blood detected by inductively coupled plasma mass spectrometry was considered as exposures, namely, cadmium (Cd), lead (Pb), total mercury (Hg), manganese (Mn), and selenium (Se). The correlations between individual metal and metal mixtures and CKD were then evaluated by survey-multivariable logistic regression (SMLR), generalized weighted quantile sum (WQS), and Bayesian kernel machine regression (BKMR). Altogether, our study included 12,412 participants representing 572.6 million non-institutionalized US adults. Several single metals with the high quartile of exposure showed a positive association with the CKD ratio including Cd [(AOR = 1.873, 95% CI: 1.537, 2.284), Q4], Pb [(AOR = 1.559, 95% CI: 1.295, 1.880), Q4], and total Hg [(AOR = 1.169, 95% CI: 1.018, 1.343), Q2], while Mn [(AOR = 0.796, 95% CI: 0.684, 0.927), Q2] and Se [(AOR = 0.805, 95% CI: 0.664, 0.976), Q4] were negatively associated with the CKD ratio. In light of the positive fit of the WQS regression model, a significantly positive correlation was found between mixed metals and CKD (AOR = 1.373, 95% CI: 1.224, 1.539) after full covariate adjustment, and a similar finding was also detected in the BKMR model. Our study revealed that each single metal including Cd, Pb, and total Hg might have a positive association with CKD while this association was negative for both Mn and Se. The five metals might have a positive joint effect on CKD.

Association of exposure to multiple serum metals with the risk of chronic kidney disease in the elderly: a population-based case-control study

In the world, chronic kidney disease (CKD) has been recognized as one of the critical public health problems, and the prevalence is higher in the elderly people. However, there are few studies on the association between exposure to multiple serum metal levels and CKD. A case-control study, we established, for elderly people in Anhui Province, China, to explore the effects of different metals and analyze the effect of mixed exposure on CKD. In this study, 287 cases of CKD and 287 controls were selected in the elderly health physical examination project in Tongling City, Anhui Province. Questionnaire survey, physical examination, and blood collection were conducted. Graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma optical emission spectrometry (ICP-OES) were used to measure the concentration of serum metals. After selecting by least absolute shrinkage and selection operator (LASSO), 5 metals were brought into the multi-metal model. After adjusting all potential covariates additionally, the concentrations of lead (Pb), cadmium (Cd), cobalt (Co), and manganese (Mn) were significantly associated with CKD risk, whereas Pb, Se, and Cd had significant non-linearity with CKD. Besides, patients with highest quartiles of cobalt (Co), lead (Pb), and manganese (Mn) were 1.64, 1.39, and 0.64 times more possible to have CKD, respectively, as compared with the lowest levels. In the Bayesian kernel machine regression (BKMR) model, cadmium (Cd) had a combined effect with lead (Pb) possibly. This study suggested that the CKD risk was associated with exposure of multiple metals in elderly people. The underlying mechanisms of serum metals and CKD need more experimental and prospective studies to elucidate.

Association of Zinc with Anemia

Zinc is an essential trace element, and anemia is the most common blood disorder. The association of zinc with anemia may be divided into three major forms: (1) zinc deficiency contributing to anemia, (2) excess intake of zinc leading to anemia, and (3) anemia leading to abnormal blood-zinc levels in the body. In most cases, zinc deficiency coexists with iron deficiency, especially in pregnant women and preschool-age children. To a lesser extent, zinc deficiency may cooperate with other factors to lead to anemia. It seems that zinc deficiency alone does not result in anemia and that it may need to cooperate with other factors to lead to anemia. Excess intake of zinc is rare. However, excess intake of zinc interferes with the uptake of copper and results in copper deficiency that leads to anemia. Animal model studies indicate that in anemia, zinc is redistributed from plasma and bones to the bone marrow to produce new red blood cells. Inadequate zinc status (zinc deficiency or excess) could have effects on anemia; at the same time, anemia could render abnormal zinc status in the body. In handling anemia, zinc status needs to be observed carefully, and supplementation with zinc may have preventive and curative effects.

Efficacy and Mechanism of Roxadustat plus Oral Iron in the Treatment of Elderly Chronic Kidney Disease with Anemia

Objective

For investigating the efficacy and mechanism of Roxadustat + oral iron in the treatment of elderly chronic kidney disease (CKD) complicated with anemia.

Methods

A total of 100 elderly patients with CKD and anemia admitted to our hospital between April 2020 and December 2021 were enrolled as research subjects, and the patients were assigned to control group (Con group, n = 50) or experimental group (Exp group, n = 50). The patients in the Con group were given oral iron, and those in the Exp group were given Roxadustat capsule based on the Con group. Both groups were given subcutaneous injection of recombinant human erythropoietin. The clinical efficacy, anemia indexes, iron metabolism indexes, inflammatory indexes, and adverse reactions were compared between the two groups.

Results

The Exp group showed a notably higher treatment effective rate than the Con group (P < 0.05). After treatment, the anemia indexes, iron metabolism indexes, and inflammatory indexes in the Exp group were notably better than those in the Con group (P < 0.05). The Exp group showed a notably lower incidence of adverse reactions during treatment than the Con group (P < 0.05).

Conclusion

Roxadustat plus oral iron yields a pronounced clinical efficacy in the therapy of elderly patients with CKD and anemia.

Association between the blood manganese (Mn) and hemoglobin in patients undergoing maintenance hemodialysis

BACKGROUND AND AIMS

Manganese (Mn) and iron metabolism are closely related. Iron metabolism disorders often lead to anemia in patients undergoing maintenance hemodialysis (MHD). Here, we aimed to investigate the relationship between blood Mn and hemoglobin (Hb) in patients undergoing MHD.

METHODS

Patients undergoing MHD in September 2019 were included in a cross-sectional study. Clinical and demographic data and blood samples were collected before hemodialysis sessions, and blood levels of Mn were measured by inductively coupled plasma mass spectrometry. Both multivariable linear and binary logistic regression analyses were performed to study the relationship between the blood Mn and Hb.

RESULTS

A total of 144 patients undergoing MHD were enrolled in the study. The patients had a mean age of 64.33 ± 13.39 years, median vintage of 33.50 (16.25-57.50) months. Among them, 66 were females (45.8%). The median blood Mn level was 13.55 µg/L (IQR:9.92-17.48). Ninety-nine patients were anemic (68.8%). The mean Hb level was 99.83 ± 19.68 g/L. The patient group with high blood Mn had a high proportion of females, and these patients had high levels of RBC, hemoglobin, Hct, UIBC, serum TCHOL, and serum LDL, yet short dialysis vintage, low prevalence of anemia, low levels of serum ferritin, serum iron, and TSAT. Following adjustment for confounding factors, we found that low blood Mn level was independently associated with lower Hb level and anemia in patients undergoing MHD by multivariate linear and multivariate binary logistic regression, respectively, in different models.

CONCLUSION

Whilst our study showed that high levels of blood Mn were independently associated with high hemoglobin in patients undergoing MHD, further multicenter studies with large sample sizes are still required.

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.

Association of Manganese Biomarker Concentrations with Blood Pressure and Kidney Parameters among Healthy Adolescents: NHANES 2013-2018

Deficiency or excess exposure to manganese (Mn), an essential mineral, may have potentially adverse health effects. The kidneys are a major organ of Mn site-specific toxicity because of their unique role in filtration, metabolism, and excretion of xenobiotics. We hypothesized that Mn concentrations were associated with poorer blood pressure (BP) and kidney parameters such as estimated glomerular filtration rate (eGFR), blood urea nitrogen (BUN), and albumin creatinine ratio (ACR). We conducted a cross-sectional analysis of 1931 healthy U.S. adolescents aged 12-19 years participating in National Health and Nutrition Examination Survey cycles 2013-2014, 2015-2016, and 2017-2018. Blood and urine Mn concentrations were measured using inductively coupled plasma mass spectrometry. Systolic and diastolic BP were calculated as the average of available readings. eGFR was calculated from serum creatinine using the Bedside Schwartz equation. We performed multiple linear regression, adjusting for age, sex, body mass index, race/ethnicity, and poverty income ratio. We observed null relationships between blood Mn concentrations with eGFR, ACR, BUN, and BP. In a subset of 691 participants, we observed that a 10-fold increase in urine Mn was associated with a 16.4 mL/min higher eGFR (95% Confidence Interval: 11.1, 21.7). These exploratory findings should be interpreted cautiously and warrant investigation in longitudinal studies.

Association of Zinc Deficiency with Development of CVD Events in Patients with CKD

Deficiency of the micronutrient zinc is common in patients with chronic kidney disease (CKD). The aim of this review is to summarize evidence presented in literature for consolidation of current knowledge regarding zinc status in CKD patients, including those undergoing hemodialysis. Zinc deficiency is known to be associated with various risk factors for cardiovascular disease (CVD), such as increased blood pressure, dyslipidemia, type 2 diabetes mellitus, inflammation, and oxidative stress. Zinc may protect against phosphate-induced arterial calcification by suppressing activation of nuclear factor kappa light chain enhancer of activated B. Serum zinc levels have been shown to be positively correlated with T₅₀ (shorter T₅₀ indicates higher calcification propensity) in patients with type 2 diabetes mellitus as well as those with CKD. Additionally, higher intake of dietary zinc was associated with a lower risk of severe abdominal aortic calcification. In hemodialysis patients, the beneficial effects of zinc supplementation in relation to serum zinc and oxidative stress levels was demonstrated in a meta-analysis of 15 randomized controlled trials. Thus, evidence presented supports important roles of zinc regarding antioxidative stress and suppression of calcification and indicates that zinc intake/supplementation may help to ameliorate CVD risk factors in CKD patients.

Zinc deficiency: its prevalence and relationship to renal function in Japan

BACKGROUND

Although zinc deficiency is common among dialyzed patients, its prevalence among non-dialyzed subjects and its relationship to renal function remain unclear.

METHODS

We selected 816 non-dialyzed subjects (495 males; mean age, 56 ± 18 years) who underwent measurement of serum zinc at Jikei University Hospital between April 2018 and March 2019 using the Standardized Structured Medical Information eXchange2 (SS-MIX2) system, a global standard in Japan that enables collection of structured medical records with automatic data transfer to a registry database system. A serum zinc level of 60-80 μg/dL was defined as marginal zinc deficiency and a level of < 60 μg/dL as absolute zinc deficiency. We investigated factors associated with serum zinc using multiple regression analysis.

RESULTS

Marginal and absolute zinc deficiency were present in 52.3% and 30.6% of subjects, respectively. Serum zinc levels tended to decrease with increasing stage of chronic kidney disease (CKD) (P = 0.051). Estimated glomerular filtration rate (eGFR) was not independently associated with serum zinc levels. Instead, serum albumin (t = 4.69, P < 0.01), hemoglobin (t = 2.54, P = 0.01) and mean corpuscular volume (MCV) (t = - 2.20, P = 0.03) were independently associated with serum zinc. In sensitivity analyses, serum zinc was not associated with either serum copper- or iron-related parameters.

CONCLUSION

This large-scale study clarified the prevalence of zinc deficiency among non-dialyzed Japanese subjects. In addition, eGFR was not independently associated with serum zinc, probably due to confounding factors, such as nutritional status and degree of anemia. Further investigations are needed to clarify the epidemiology of zinc deficiency and its associations with CKD.

Serum trace metal association with response to erythropoiesis stimulating agents in incident and prevalent hemodialysis patients

Alterations in hemodialysis patients' serum trace metals have been documented. Early studies addressing associations levels of serum trace metals with erythropoietic responses and/or hematocrit generated mixed results. These studies were conducted prior to current approaches for erythropoiesis stimulating agent (ESA) drug dosing guidelines or without consideration of inflammation markers (e.g. hepcidin) important for regulation of iron availability. This study sought to determine if the serum trace metal concentrations of incident or chronic hemodialysis patients associated with the observed ESA response variability and with consideration to ESA dose response, hepcidin, and high sensitivity C-reactive protein levels. Inductively-coupled plasma-mass spectrometry was used to measure 14 serum trace metals in 29 incident and 79 prevalent dialysis patients recruited prospectively. We compared these data to three measures of ESA dose response, sex, and dialysis incidence versus dialysis prevalence. Hemoglobin was negatively associated with ESA dose and cadmium while positively associated with antimony, arsenic and lead. ESA dose was negatively associated with achieved hemoglobin and vanadium while positively associated with arsenic. ESA response was positively associated with arsenic. Vanadium, nickel, cadmium, and tin were increased in prevalent patients. Manganese was increased in incident patients. Vanadium, nickel, and arsenic increased with time on dialysis while manganese decreased. Changes in vanadium and manganese were largest and appeared to have some effect on anemia. Incident and prevalent patients' chromium and antimony levels exceeded established accepted upper limits of normal.

Lower Metal Element Levels in Hypertrophic Scars: A Potential Mechanism of Aberrant Cicatrix Hyperplasia

Background

We investigated levels of the metal elements Ca, Mg, Zn, Fe, and Cu in blood, normal skin (NS), and different types of scar tissue and aimed to elucidate the pathogenesis of hypertrophic scars (HS).

Material/Methods

Tissue specimens were excised from 3 groups of research participants: scar-free, flat scar (FS), and HS groups. Levels of the study elements were measured in blood, NS, and scar tissues with a spectrophotometer. The levels in plasma or in different types of specimens were compared among subgroups. In the FS and HS groups, levels were compared between the scar tissue and NS of each individual. In addition, element differences in exposed and unexposed areas of NS were investigated in the scar-free group. HS fibroblasts (HFB) were cultured in medium with various reduced levels of metal elements to determine the influence of metal elements on fibroblast growth.

Results

Levels of trace elements, including Zn, Fe, and Cu, were significantly lower in HS than in FS. The levels of Ca, Zn, Fe, and Cu were markedly lower in HS than in the patients’ own NS, while the Cu/Zn ratio was higher. However, no such difference was observed in the FS group. No significant difference in element levels was found in either plasma or NS among the 3 groups. Reduced levels of the elements promoted HFB proliferation within 24 h while an inhibition effect was observed at 72 h.

Conclusions

Our findings indicate reduced levels of metal elements in part of the healing microenvironment, suggesting that decreased metal levels may be involved in the pathogenesis of HS.