Factors Affecting Timing of Hypothyroidism Following Radioactive Iodine Therapy Patients With Graves Disease

Study Overview
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Brief Summary
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The purpose of this retrospective study was to clarify the possible risk factors of early hypothyroidism after RAI therapy in Graves' disease.

Detailed Description
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Hyperthyroidism is a clinical syndrome caused by increased thyroid hormone in the blood, it can lead to multiple complications, including cardiac, hepatic, and hematologic system complications. More than 80% of hyperthyroidism are caused by Graves' disease (GD). 3% of women and 0.5% of men may suffer GD in their lifetime [1]. Radioactive iodine (RAI) therapy is an important treatment option for Graves' disease (GD), the main side effect of RAI treatment is hypothyroidism, and the factors resulting in hypothyroidism are still controversial [2]. Male gender, smaller thyroid weight, higher thyroid-stimulating hormone, and smaller thyroid volume are Suggested to be the main risk factors for early hypothyroidism [2]-[3].

Official Title
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Factors Affecting Timing of Hypothyroidism Following Radioactive Iodine Therapy Patients With Graves Disease

Conditions
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Radioactive Iodine-Induced Hypothyroidism in Graves Disease Patients

Intervention / Treatment
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* Radiation: Radioactive Iodine therapy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Graves' disease patients after one year of RAI therapy . Suppressed serum thyrotropin (TSH) <0.55 µU/ml , elevated serum free triiodothyronine (FT3) > 6.5 pmol/L , free thyroxin FT4 >22.7 pmol/L . Exclusion Criteria: Patients with other causes of hyperthyroidism , such as toxic multinodular goiter and single toxic adenoma Thyroid cancer Recurrent GD Previous Thyroid surgery Patients can't complete the follow -up within 6 months.

Ages Eligible for Study
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Minimum Age: 13 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Hypothyroidism<br>decreased hormone levels (FT3 < 3.5 pmol/L, FT4 < 11.5 pmol/L, TSH > 4.78 μU/mL) and symptoms of hypothyroidism within 6 months' follow-up. | Radiation: Radioactive Iodine therapy<br>* All the patient need to stop ATD and iodine-containing drugs for 5 days prior to RAI treatment, and followed a low-iodine diet for 2 weeks. After fasting and water deprivation for 8 h, all the patients took RAI orally in the morning. After taking RAI, the patients need to continue fasting and water deprivation for extra 2 h to avoid the effects of food on iodine absorption.<br>|
| Euthyroidism<br>normal hormone levels (FT3 3.5 to 6.5 pmol/L, FT4 11.5 to 22.7 pmol/L, TSH 0.55 to 4.78 μU/mL), and no symptoms of hyperthyroidism after 6 months' follow-up | Radiation: Radioactive Iodine therapy<br>* All the patient need to stop ATD and iodine-containing drugs for 5 days prior to RAI treatment, and followed a low-iodine diet for 2 weeks. After fasting and water deprivation for 8 h, all the patients took RAI orally in the morning. After taking RAI, the patients need to continue fasting and water deprivation for extra 2 h to avoid the effects of food on iodine absorption.<br>|
| Hyperthyroidism<br>increased hormone levels (FT3 > 6.5 pmol/L, FT4 > 22.7 pmol/L, TSH < 0.55 μU/mL) and symptoms of hyperthyroidism after 6 months' follow-up | Radiation: Radioactive Iodine therapy<br>* All the patient need to stop ATD and iodine-containing drugs for 5 days prior to RAI treatment, and followed a low-iodine diet for 2 weeks. After fasting and water deprivation for 8 h, all the patients took RAI orally in the morning. After taking RAI, the patients need to continue fasting and water deprivation for extra 2 h to avoid the effects of food on iodine absorption.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| predictive factors of early hypothyroidism after RAI therapy | Retrospective study from 2013 to 2022 to analyze the correlation between clinical, demographic& and laboratory data and incidence of hypothyroidism by measuring thyroid function tests | 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| the incidence of hypothyroidism within 1 year | To detect the frequency of hypothyroidism after RAI and when it is most likely occur after 6 months or one year | 10 years |