Study On The Correlation Between TPOAb And Hypothyroidism After ¹³¹I Treatment Of Graves Hyperthyroidism

Background:Hyperthyroidism refers to a group of clinical syndromes in which excessive thyroid hormone produced by the thyroid gland itself leads to increased excitability and metabolic hyperactivity in various systems.The causes of hyperthyroidism mainly include autonomous high function thyroid adenoma,nodular toxic goiter and hyperthyroidism of Graves.The incidence rate of clinical hyperthyroidism in China is 0.8%,among which,hyperthyroidism caused by Graves’disease accounts for more than 80%.The risk of hyperthyroidism caused by Graves’disease is 3%for women and 0.5%for men.Currently,there are mainly three treatments for Graves’hyperthyroidism:131I,antithyroid drugs and surgical treatment.Although these three treatments have been proved effective,the choice of treatment is still influenced by many factors,such as social economy and culture.131I treatment has been increasingly used as the first-line treatment for Graves hyperthyroidism due to its simplicity,economy,safety and efficiency.It can quickly correct hyperthyroidism,with a success rate of 93%and an adverse reaction rate of 6%.However,131I May be followed by hypothyroidism（hypothyroidism）,which requires lifelong thyroid hormone replacement therapy and regular follow-up during replacement therapy.Anti-thyroid peroxidase antibody（TPOAb）is one of the most common autoantibodies associated with hyperthyroidism of Graves.For the thyroid peroxidase patients with TPOAb,The incidence of hypothyroidism after 131I treatment is about 2%to 3%per year,even if thyroid function returns to normal,due to the delayed effects of radiation from 131I treatment and the destruction of thyroid tissue by lymphocyte infiltration.At present,the relationship between TPOAb and hypothyroidism after treatment of 131I remains unclear,and there are few relevant studies.For patients with Graves hyperthyroidism,further clarifying the relationship between TPOAb before treatment of 131I and hypothyroidism after treatment is of vital clinical significance in reducing the incidence of hypothyroidism after treatment.Objective:To analyze the relationship between thyroid peroxidase antibody（TPOAb）in patients with Graves hyperthyroidism and hypothyroidism after 131I treatment,so as to provide a theoretical basis for predicting the outcome of thyroid function after 131I treatment.Methods:According to the inclusion and exclusion criteria,122 patients with Graves hyperthyroidism who received 131I treatment in Huaihe Hospital of Henan University from January 2016 to December 2021were retrospectively selected.Basic data and examination results of patients before 131I treatment were collected.Thyroid function was collected at outpatient reexamination at 3 and 6 months after 131I treatment.According to patients’pre-treatment TPOAb levels,TPOAb≤34 IU/ml was defined as negative,and TPOAb>34 IU/ml was defined as positive.According to the thyroid function of 131I at 3 months and6 months after treatment,the patients were divided into 3 groups:hyperthyroidism group,normal thyroid function group and hypothyroidism group.SPSS 25.0 was used for statistical analysis.General information,related indicators and thyroid function at the 3rd and 6th month of the TPOAB-negative group and the TPOAB-positive group were statistically analyzed,and univariate and multivariate logistic regression analysis was conducted.To analyze the relationship between TPOAb level before treatment and hypothyroidism in patients with Graves hyperthyroidism at 3 and 6 months after 131I treatment.According to the results of multivariate logistic regression analysis,the ROC curve analysis of TPOAb level was carried out.Results:1.FT₄,TSH and TRAb in the TPOAB-positive group were higher than those in the TPOAB-negative group before 131I treatment,and the thyroid volume in the TPOAB-positive group was also higher than that in the TPOAB-negative group,with statistical significance（p<0.05）.There were no significant differences between TPOAB-positive group and TPOAB-negative group in gender,age,course of disease,thyroid iodine uptake rate,FT3,iodine dose,smoking status,thyroid nodule status,and antithyroid drug administration before iodine administration（p>0.05）.2.At the 3th month,hyperthyroidism occurred in 16.1%of patients in the TPOAB-positive group after¹³¹I treatment,17.1%in the TPOAB-negative group（p=0.085）,and hypothyroidism in 80.2%of patients in the TPOAB-positive group after ¹³¹I treatment,63.4%of patients in the TPOAB-negative group（p=0.044）,3.7%of patients in the TPOAB-positive group had normal thyroid function after ¹³¹I treatment,and 19.5%of patients in the TPOAB-negative group（p=0.011）.At the 6th month,hyperthyroidism occurred in 6.2%of patients in the TPOAB-positive group after ¹³¹I treatment,in 9.8%of patients in the TPOAB-negative group（p=0.727）;in 81.5%of patients in the TPOAB-positive group after ¹³¹I treatment,and 61.0%of patients in the TPOAB-negative group had hypothyroidism（p=0.014）,12.3%of patients in the TPOAB-positive group had normal thyroid function after ¹³¹I treatment,and 29.2%of patients in the TPOAB-negative group（p=0.022）.3.In univariate logistic regression analysis,positive TPOAb was associated with hypothyroidism at both 3 and 6 months after ¹³¹I treatment（3 months:OR:2.344;95%CI:1.013 5.421;p=0.046;The sixth month:0R:2.816;95%CI:1.214 6.532;p=0.016）;In multivariate logistic regression analysis,after adjusting for age before 131I treatment,FT₄,TRAb,thyroid volume,whether anti-thyroid drugs were taken before iodine administration and iodine dosage,TPOAb positive was not associated with hypothyroidism at the 3rd month,but was associated with hypothyroidism at 6 months（adjusted for OR at 3 months:2.555;95%CI:0.916 7.128;p=0.073;The sixth month adjusted OR:3.452;95%CI:1.334 8.868;p=0.010）.4.According to the results of multivariate logistic regression analysis,the ROC curve of TPOAb level in positive patients was prepared:AUC value was 0.737,sensitivity was 68.18%,specificity was 80.00%,indicating that TPOAb had certain predictive value for hypothyroidism after 131I treatment.The cutoff value calculated by Yoden index was 413.50IU/ml,indicating that patients with Graves hyperthyroidism were more likely to have hypothyroidism after 131I treatment when TPOAb level exceeded 413.50IU/ml（p<0.001）.Conclusions:1.In patients with Graves’hyperthyroidism treated with ¹³¹I,positive TPOAb was associated with hypothyroidism after ¹³¹I treatment.2.Hypothyroidism was more likely to occur at 6 months after treatment with ¹³¹I when pre-treatment TPOAb≥413.50IU/ml.3.This study is helpful for clinicians to predict the outcome of thyroid function after ¹³¹I treatment according to the TPOAb level of patients with Graves’hyperthyroidism before ¹³¹I treatment,and help patients to timely intervene in hypothyroidism.