The Study On The Mechanism Of The Occurance Of Hypothyroidism With ¹³¹I For GD

Objective: The patients with hypothyroidism after ¹³¹I treatment of Graves' hyperthyroidism were followed up by detecting the serum thyroid hormone?FT₃, FT₄, TSH? levels, antibody?Tg Ab and TPOAb? and RAIU.Analysis the correlation between various factors and the development of hypothyroidism and explore the effects of various factors on the development of hypothyroidism, So as to provide more accurate guidance for the treatment of Graves hyperthyroidism.Methods:It was retrospective review of the patients with ¹³¹I treatment for GD from 2005 to 2015 and reexamining from March 2015 to January 2016.1 The patient's history were collected,including gender, age, autoimmune antibody levels during the ¹³¹I treatment,RAIU, The time interval of hypothyroidism after treatment of hyperthyroidism.2 Check the serum thyroid hormone?FT₃, FT₄, TSH? levels, antibody levels.The patients' RAIU,thyroid static scan and Thyroid weight were detected under the premise of maintaining normal serum thyroid hormone levels in patients through different dose of L-T₄.3 Process the clinical data by SPSS 21 software,so as to analyse the differences between groups.Results: There are 124 cases were followed up and 124 cases with complete data,including 31 males and 93 females.The age range from 11 years old to 71 years old, mean age is 37.92±19.50 years old. To maintain the normal level of serum thyroid hormone, the patients took a dose of L-T₄ 25?g ¹75?g per day, with the mean dose64.01±30.89?g. TPOAb with 3000U/ml as the community is divided into low TPOAb group and high TPOAb group, 300IU/ml to Tg Ab as the community is divided into low Tg Ab group and high Tg Ab group.The 24 h RAIU ranges from 1% to 62%,and among these patients, normal 79 cases?63.7%?, lower in 41 cases?33.1%?, increased in 4 cases?3.2%?.1 Patients studied were divided into 5 groups: Group A contains 14 cases?10.9%? with low antibody and reduced 24 h RAIU. Group B contains 16 cases?12.7%? with low antibody and normal 24 h RAIU. Group C contains 29 cases?23.6%? with high antibody and reduced 24 h RAIU. Group D contains 61 cases?49.1%? with high antibody and normal 24 h RAIU. Group E contains 4 cases?3.6%? with high antibody and increased 24 h RAIU.2 According to the results of the thyroid imaging,4 cases thyroid weight were not measured because of the low thyroid uptake function,which causes the unclear boundaries between the thyroid gland and the surrounding tissue. Among the other 120 patients, the thyroid weight ranges from 6g to 37 g and the average is 21.78±6.18 g. With 20 g 25 g as the normal reference value, 36 cases?30%? were smaller than the normal range, 50 cases?41.7%? were normal, and 34 cases?28.3%? were larger than the normal range.3 There were 12 cases with the less thyroid weight in 46 cases of early hypothyroidism. There were 28 cases with the less thyroid weight in 78 cases of late hypothyroidism.4 Divide the data into different groups according to different factors,and compare the dose of L-T₄ between different groups.The data of L-T₄ dose doesn't conform to the normal distribution, the results using non parametric comparison are as follows:4.1 According to the levels of Tg Ab and TPOAb During the period of hypothyroidism and TPOAb before the ¹³¹I treatment,the patients were divided into high level antibody group and low level antibody group. The P values were more than 0.05, and there was no statistical difference between the groups. The patients were divided into the reduction group and the normal group by 24 h RAIU. The P value was less than 0.01, and there were significant statistical differences between the groups.4.2 According to the time interval of hypothyroidism after treatment of hyperthyroidism, the patients were divided into early hypothyroidism group and late hypothyroidism group.The P value is less than 0.05, and there were statistically significant differences between groups. According to the time interval of hypothyroidism after treatment of hyperthyroidism, the patients with late hypothyroidism were divided into 2⁵ years group and 5¹0 years group.The P value was more than 0.05, and there was no statistical difference between the groups.4.3 The patients were grouped according to their age and every 20 years as a unit. The P value was more than 0.05, and there was no statistical difference between the groups. According to gender, the patients were divided into two groups.The P value is less than 0.05, and there were statistically significant differences between groups.Conclusion:1 In addition to the high level of thyroid autoimmune antibodies` destructive effect,the patients with hypothyroidism after ¹³¹I treatment of Graves' hyperthyroidism are also associated with chronic radiation damage of ¹³¹I.2 The TPOAb and Tg Ab increase after the ¹³¹I treatment and begin to decline after 6⁹ months of treatment,and thechanges are at the trend of first to rise and then drop after ¹³¹I treatment. The early hypothyroidism is realated to the radiation damage of ¹³¹I and the thyroid follicle damage by the increased antibody due to the radiation injury.3 The results of the correlation analysis of the L-T₄ dose of hypothyroidism after ¹³¹I therapy for hyperthyroidism Graves are as follows: The dose of L-T₄ is not realated to the age and the levels of serum autoimmune antibodies?TPOAb, Tg Ab? before and after the treatment ¹³¹I. The dose of L-T₄ is realated to the radioactive injury of thyroid follicles by ¹³¹I. The greater of damage extent, the higher L-T₄ dose. The dose required for male is higher than female.There are differences in the dose of L-T₄ between early hypothyroidism and late hypothyroidism. The dose required for early hypothyroidism is higher than late hypothyroidism. There is no difference in the dose of L-T₄ of different time interval of hypothyroidism after treatment of hyperthyroidism among the late hypothyroidism patients.