The Research Of Selenium Supplementation On The Curative Effect And Mechanism In Chronic Lymphocytic Thyroiditis

Objective:To explore the effect and working mechanism of selenium supplementation on the oxidative antioxidant systems,inflammatory cytokines,thyroid autoantibodies and thyroid function in patients with Chronic lymphocytic thyroiditis（CLT）,also known as Hashimoto thyroiditis（HT）.Methods:The 60 cases of HT subjects were randomized into the selenium group（group A）and levothyroxine group（group B）.According to the status of thyroid function,group A and B were further divided into A1 subgroup,B1 subgroup（euthyroidism）and A2 subgroup,B2 subgroup（hypothyroidism）respectively.Patients in group A and B were both treated with levothyroxine（minimum dose of 25μg/d）to maintain TSH in the normal range（0.4⁴.0mIU/L）.Besides,patients in group A received particular treatment of selenium yeast capsule 400μg/d.The treatment lasted for 3 months.Normal control group（NC group）consists of another 30 cases of healthy subjects.Subjects in all groups were tested on the serum concentrations of selenium,malondialdehyde（MDA）,glutathione peroxidase（GPX）activity,interleukin 2（IL 2）,interleukin 10（IL-10）,thyroid peroxidase antibody（TPOAb）,thyroglobulin antibody（TgAb）and thyroid function before and after treatment.Changes of each index between each group were compared and the correlations of the indexes were also analyzed.Results:1.Changes of serum selenium concentrations:The basal serum selenium concentrations in HT patients（group A and B）was significantly lower than NC group,in which hypothyroidism patients（A2 subgroup and B2 subgroup）was lower than euthyroidism patients（A1 subgroup and B1 subgroup）（P<0.05）;after treatment,the serum selenium concentrations in group A increased greatly（P<0.05）,while in group B there was no obvious change（P>0.05）;2.Changes of oxidative antioxidant indexes:In HT patients,the basal GPX activity was significantly lower than NC group and the basal serum concentrations of MDA was significantly higher than NC group（P<0.05）;after treatment,the GPX activity increased greatly and the serum concentrations of MDA decreased greatly in group A（P<0.05）,whereas the two indexes had no obvious changes in group B（P>0.05）;3.Changes of inflammatory factors levels:In HT patients,the basal IL-2 concentrations was remarkably higher than NC group and the basal IL-10 concentrations was remarkably lower than NC group（P<0.05）.After treatment,the IL-2 concentrations decreased greatly in group A（P<0.05）,whereas group B had no obvious change（P>0.05）;the IL-10 concentrations increased remarkably both in group A and B（P<0.05）,and the elevation of IL-10 concentrations had no statistically significant difference between group A and B（P>0.05）.4.Changes of thyroid autoantibodies levels:After treatment,the thyroid autoantibodies（TPOAb、TgAb）in group A decreased remarkably（P<0.05）,while the decline in group B is not obvious（P>0.05）;5.Changes of thyroid function:After treatment,TSH decreased obviously in hypothyroidism patients（A2 subgroup,B2 subgroup）（P<0.05）,but the changes of thyroid function（TT3、TT4、TSH）were not remarkable in the rest groups（P>0.05）;6.Correlation analysis of of the indexes:In HT patients,the basal serum selenium concentration was positively correlated with TT₄（r=0.294,P<0.05）,and significantly negatively correlated with TSH（r=-0.343,P<0.01）;IL-10 was significantly positively correlated with TT₄（r=0.306,P<0.05）,and significantly negatively correlated with IL-2（r=-0.597,P<0.01）,the rest had no significant correlation（P>0.05）.Conclusions:1.the serum selenium concentrations in HT patients is significantly lower than the normal population;the heavier the degree of hypothyroidism,the lower the serum selenium concentration.Selenium yeast can elevate the serum selenium concentrations in HT patients.2.In HT,the antioxidant effect is weakened,while the oxidation reaction is enhanced;selenium supplementation can strengthen the antioxidant capacity and may help to reduce the oxidative damage in HT.3.Selenium supplementation can decrease the IL-2 concentrations and increase the IL-10 concentrations and may alleviate immune inflammatory lesions in HT.4.Selenium intervention can help to reduce the thyroid autoantibodies（TPOAb、TgAb）levels in HT patients.5.Selenium supplementation has no significant effect on thyroid function.6.The above results indicate that in this study the treatment effect of selenium combined with levothyroxine is superior to the single use of the latter,but it still needs further research to determine whether selenium supplementation can be a new control approach in HT.