Association Of Internal Exposure Levels Of Lead,Cadmium,and Mercury With Hyperuricemia Among Older Adults

Objective:The purpose of this study is to explore the association between internal exposure levels of lead,cadmium and mercury with hyperuricemia,and reveal the interaction between heavy metals,so as to provide scientific basis for controlling the internal exposure levels of heavy metals and developing prevention and treatment measures for hyperuricemia.Methods:Data for this study were obtained from the third follow-up study(2017-2018)of the Healthy Aging and Biomarkers Cohort Study.Data were collected by questionnaire survey combined with physical examination and biological sample collection and detection.Hyperuricemia was defined according to blood uric acid level.Spearman rank correlation was used to analyze the correlation between heavy metal levels and uric acid level.The association between internal exposure levels of lead,cadmium and mercury in blood and urine and the risk of hyperuricemia in older adults was analyzed using multivariate logistic regression model.To explore the dose-response relationship between heavy metal levels and hyperuricemia,we used restricted cubic spline to demonstrate possible linear/non-linear associations in the whole model.Furthermore,subgroup analyses were conducted to compare the association in populations with different characteristics,and to explore whether there were modification effects of age and gender,which might help identifying sensitive populations.Considering that heavy metals were mostly mixed exposure in human body,this study also investigated the interaction between the three heavy metals through multiplication and addition interaction analysis,and conducted sensitivity analysis to verify the stability of the results.Results:1.Description of basic characteristics of the participants.In the study on the association between blood lead,cadmium,mercury and hyperuricemia,we included 2447 participants(aged ≥ 65 years),including 421 patients with hyperuricemia,and the overall uric acid level was 330.0(277.0,394.0)μmol/L and age was 84.0(75.0,94.0)years.In the study on the association between urine lead,cadmium,mercury and hyperuricemia,1970 subjects were included,with 336 patients with hyperuricemia,and the overall uric acid level was 331.0(279.0,395.0)μmol/L and age was 83.0(74.0,92.0)years.There were statistically significant differences in blood lead,cadmium,mercury and urine lead levels between hyperuricemia and nonhyperuricemia groups(P<0.05).2.Association analysis of lead,cadmium and mercury levels with uric acid levels and hyperuricemia.Spearman rank correlation analysis showed that blood lead,cadmium and mercury levels were positively correlated with uric acid level.The rank correlation coefficient was 0.060,0.128 and 0.196,respectively.The levels of urine lead and mercury was negatively correlated with uric acid level.Multivariate logistic regression analysis showed that the group of the fourth quartile of blood lead levels had a higher risk of hyperuricemia than the first quartile without adjusting for any confounding factors,with an OR(95%CI)value of 1.44(1.05～1.96).The group of the fourth quartile of urine lead levels had a lower risk of hyperuricemia with an OR(95%CI)value of 0.71(0.51-0.98).After adjusting for confounding factors,the risk of hyperuricemia was higher in the fourth quartile of blood cadmium and blood mercury levels,and the OR(95%CI)values were 2.30(1.55-3.42)and 2.27(1.59-3.26),respectively.No association was found between blood lead,urine lead,urine cadmium,urine mercury and hyperuricemia.3.Dose-response relationship between lead,cadmium and mercury levels and hyperuricemia.The results of restricted cubic spline fitting multiple logistic regression model showed that blood cadmium and blood mercury levels were associated with the risk of hyperuricemia in non-linear manner,and the higher the heavy metal internal exposure levels were,the higher the risk of hyperuricemia was.4.Subgroup analysisSubgroup analysis showed that the association between blood mercury and hyperuricemia was stronger in the group of 65-79 years than in 80 years and older.5.Interaction analysisInteraction analysis showed that there was no multiplication and addition interaction between lead,cadmium and mercury levels in blood and urine.Conclusions:1.There was a positive nonlinear association between blood cadmium and blood mercury levels and the risk of hyperuricemia among older adults,the higher internal exposure levels of blood cadmium and blood mercury were,the higher the risk of hyperuricemia was.2.The association between blood mercury levels and hyperuricemia was modified by age.The association between blood mercury levels and hyperuricemia was stronger in older adults aged 65-79 years.3.No statistical or biological interaction between the three heavy metals levels in blood and urine was found.