The Concentration Of 17 Trace Elements In Serum And Its Association With Thyroid Function And The Risk Of Thyroid Diseases In Children

Objective:The importance of the thyroid gland in maintaining human health is well recognized.Certain microelements,excepted for iodine,were involved in thyroid hormone metabolism in the last decades.However,few studies evaluated the individual iodine status.Therefore,this study aims to detect 17 serum trace elements in school-aged children（7-14y）and clarify their association with thyroid hormones and then explore the relationship between elements and the risk of subclinical hypothyroidism（SCH）,simple goiter,autoimmune thyroiditis（AIT）and thyroid nodule（TN）in children with different iodine status,and the predictive ability on thyroid disease.Method:A cross-sectional survey of serum elements concentration in children with different iodine intake areas in Shandong,China.And a case-control study on the association between the microelements and thyroid disease risk.Iodine status was assessed by the 24-h urine iodine excretion.Serum samples were collected to determine elements and thyroid hormones.The contents of thyroid volume and nodules were measured with ultrasonic.The subjects of the case-control study were matched by the propensity score matching.The relationship between serum elements and thyroid diseases was analyzed with conditional logistic and grouped according to the quartiles（Q1-Q4）of serum concentration to calculate the odds ratio（OR）at different levels.OR curves were fitted with cubic splines.The receiver operating characteristic curves（ROC）were used to compare the effect of elements in diagnosing thyroid diseases.Results:A total of 1977 school-aged children in Shandong Province from Ningjin,Lingxian,Gaotang and Dongchangfu included analysis.The percentage of children with SCH,goiter,AIT and TN was 10.07%、10.62%、6.57%and 25.56%,respectively.The serum total iodine（St I）and serum non-protein-bound iodine（Snb I）were 98.05（84.68,113.19）μg/L and 52.97（44.55,64.71）μg/L,respectively.The concentration of Fe,Cu,Zn,Se,Co,Cr and Mo were 1414.31（1091.02,1955.76）μg/L,990.34（872.26,1118.09）μg/L,806.28（712.42,940.83）μg/L,76.69（66.8,85.61）μg/L,0.15（0.10-0.22）μg/L,0.40（0.12-0.90）μg/L and 0.96（0.68 1.47）μg/L,respectively.The concentration of V,Mn and Ni were 0.16（0.06,0.26）μg/L,0.69（0.10,1.95）μg/L and 1.33（0.41,2.85）μg/L,respectively.The concentration of As and Cd were 1.07（0.68,1.60）μg/L and 8.76（3.70,37.55）ng/L,respectively.The levels of Rb,Sr,Sb and Ba were 149.21（124.45,178.06）μg/L,80.65（67.15,98.53）μg/L,0.04（0.01,0.17）μg/L and 38.09（26.04,50.79）μg/L,respectively.Serum Zn,Fe,Cr,Mo,V and Ni positively correlated with FT3 and FT4 while Zn,V and Ni were negatively correlated with TSH.Conditional logistic regression was used to analyze the relationship between serum microelements.1)Serum Snb I snd Cd had a positive related trend with the odds of SCH,P-trend<0.05.However,children with adequate Zn could reduce the risk of SCH[Q4:OR=0.45（95%CI:0.23,0.89）].2)Simple goiter in children was mainly related to iodine nutrition status[Q4:OR=2.29（95%CI:1.17,4.46）,P_trend<0.001].3)Iodine excessive also increased the risk of AIT[Q4:OR=2.73（95%CI:1.24,5.99）],while the sufficient zinc in children had a protective effect[Q4:OR=0.18（95%CI:0.08,0.40）],P_trend<0.001.4)The result revealed a significant positive trend among the odds of TN and Snb I,Ni and Cd[the OR was 4.21（95%CI:1.50,11.84）,4.00（95%CI:1.33,12.03）and 3.33（95%CI:1.11,10.01）for Q4,respectively,P_trend<0.05].The risk of TN was significantly increased with insufficient Zn[relative to Q2,OR=2.51（95%CI:1.08,5.83）for Q1,P_trend<0.05].5)When St I>80μg/L、Snb I>65μg/L、Zn<700μg/L、Ni>4.3μg/L、Cd>12.2 ng/L,the prevalence of thyroid diseases increased.6)Stratified analysis showed that gender,age and iodine status had no significant modifying effect on the relationship among serum elements and thyroid disease risk（P-interaction>0.05）.The ROC showed that the addition of multiple elements of Snb I,Zn,Ni and Cd significantly improved the prediction of SCH,AIT and TN in children.Conclusions:1.The serum trace elements were correlated with thyroid hormone and24-h UIE.2.High Snb I level increased the risk of SCH,AIT and TN in children,while Adequate zinc nutrition is a protective factor.3.High levels of exposure to essential microelement Ni may increase the risk of thyroid nodule in children.4.Exposure to Cd,a potentially toxic metal element,increases the risk of SCH and TN in children,and the dose-effect increases linearly.5.Combined serum elements could improve the prediction of SCH,AIT and TN in children.