Associations Between Blood Trace Elements And Lipid Metabolism Disorders As Well As Sarcopenia In Patients With Maintenance Hemodialysis:A Double-center And Cross-sectional Study

Part Ⅰ: Distribution of blood trace elements in patients with maintenance hemodialysis in the two centersObjectives: To investigate the distribution of blood trace elements in patients with maintenance hemodialysis(MHD)and their correlations with residual cholesterol(RC)and appendicular skeletal muscle mass index(ASMI).Methods: A double-center and cross-sectional study.Patients who underwent regular MHD in Guangzhou Red Cross Hospital and Jiangmen Central Hospital from September 2021 to December 2021 were included.General and clinical data were collected.Inductively coupled plasma mass spectrometry(ICP-MS)was used to detect trace elements in whole blood.Post-dialysis body composition was measured using a body composition analyzer(BIA).Spearman analysis was used to analyze the correlation of trace elements in whole blood with RC and ASMI.Results: Results: A total of 452 MHD patients were included.The distribution of selenium,zinc,rubidium and nickel in whole blood was normal or nearly normal,while the distribution of Copper,vanadium,chromium,cobalt,cadmium,manganese,molybdenum and lead was skewness.Spearman analyses showed that blood chromium and selenium were positively correlated with RC(all P <0.05),whereas blood vanadium,cadmium,rubidium,nickel,molybdenum,lead were negatively correlated with RC(all P<0.05).ASMI was negatively correlated blood copper,vanadium,cadmium,and manganese(all P<0.05).Among them,the correlation coefficients of whole blood nickel and cadmium with RC(r=-0.345,P=0.007)and ASMI(r=-0.241,P=0.001)were the largest in absolute value.Conclusions: In this study,some MHD patients had whole blood copper,manganese,zinc and rubidium deficiency,and some MHD patients had whole blood cobalt,cadmium and molybdenum accumulation.It is possible that there were independent associations between nickel and RC,as well as cadmium and sarcopenia.Part Ⅱ: Associations between blood nickel and lipid metabolism disorder in hemodialysis patientsObjective: To investigate the relationship between blood nickel and lipid metabolism disorder in MHD patients.Methods: Patients undergoing MHD in the two centers were included.Clinical data were collected before heomdialysis sessions.The threshold-saturations effect of blood Ni on RC and high RC(RC≥0.8mmol/L)were analyzed by smooth curve fitting analyses with univariate and multivariate methods.The log-likelihood ratio test was performed to compare the differences in the correlation of variables fitted by the simple linear regression model and the two-segment linear model.Clinical factors associated with high RC were analyzed by univariate binary logistic regression.Multivariate binary logistic regression was used to adjust for possible confounding factors,and subgroup analyses were performed to explore the association between whole blood nickel and high RC in different populations,and the results were presented using forest plots.Results: A total of 420 MHD patients were included.Compared with the non-high RC group,the patients in the high RC group had older age,higher diabetes ratio,BMI value,WBC level,lymphocyte count,and shorter dialysis age,and lower whole blood nickel,predialysis creatinine level(P<0.05).After adjusting for confounding factors,the curve fitting results show that there is a curve relationship between the blood Ni and RC.When the blood Ni≤3.6μg/L,RC decreases by0.2mmol/L for every 1μg/L increase of whole blood Ni(P<0.001),but when whole blood Ni > 3.6μg/L,a saturation effect occurred.So there is a curve fitting relationship between whole blood Ni and high RC.When whole blood Ni ≤ 3.6 μg/L,the risk of high RC decreases by 70% for every 1 μg/L increase of whole blood Ni(P<0.001).When blood nickel>3.6μg/L,saturation effect occurs.Adjusting for dialysis age,BMI,pre-dialysis creatinine,and complete blood lymphocyte count,and stratified by age ≥65,gender,and diabetes,the results show that the overall lower blood Ni was independently associated with higher RC,and the association was significant in the subgroups of diabetes and elderly patients(P<0.05 for all interaction effects).Conclusions: Lower blood nickel in MHD patients was independently associated with RC and high RC,and this association was significant when the blood nickel ≤ 3.6 μg/L.Part Ⅲ: Association between the blood cadmium and sarcopenia in patients with maintenance hemodialysisObjective: To investigate the associations between the blood cadmium and sarcopenia in patients with MHDMethods: Patients undergoing MHD in the two centers were included.Clinical data were collected before heomdialysis sessions.The threshold-saturation effects of blood cadmium on ASMI and grip strength were analysed by smooth curve fitting analyses with univariate and multivariate methods.The log-likelihood ratio test was performed to compare the differences in the correlation of variables fitted by the simple linear regression model and the two-segment linear model.Clinical factors associated with sarcopenia were analyzed by univariate binary logistic regression.Multivariate binary logistic regression was used to adjust for possible confounding factors,and subgroup analyses were performed to explore the association between blood cadmium and sarcopenia in different populations,and the results were presented using forest plots.Results: A total of 339 MHD patients were included.Compared with the non-sarcopenic group,the patients in the sarcopenic group had older age,higher body fat,whole blood vanadium,whole blood cadmium,and lower WBC,neutrophil count,lymphocyte count,Serum creatinine,ALB,TG,ASMI,grip strength,moisture(%)and BFMI before dialysis(P<0.05).After adjusting for confounding factors,the relationship between whole blood cadmium and ASMI was curviline.When whole blood Cd≤3.5 μg/L,ASMI decreased by 0.2kg/m~2 for every 1μg/L increase(P<0.001),but when whole blood Cd > 3.5μg/L,saturation effect occurs.After adjusting for the same confounding factors,the relationship between whole blood Cd and grip strength was curve fitting.When whole blood Cd≤4.7 μg/L,grip strength decreased by 1.1kg(P=0.004)for every 1μg/L increase,while saturation effect occurs when whole blood Cd > 4.7μg/L.Adjusting for confounding factors as dialysis age,predialysis creatinine,ALB,hs CRP,TG,and BFMI,and stratified by age ≥65,gender,and diabetes,the results show that the higher blood cadmium and sarcopenia were independent associated.The association was without statistically significant difference between subgroups(P>0.05 for all interaction effects).Conclusion: Higher blood cadmium was independently associated with sarcopenia in MHD patients.