Graves’ disease is the leading cause of hyperthyroidism, with a population prevalence of approximately 0.5%, most commonly occurring in women aged 40-60 years. Radioactive iodine (131I) and antithyroid drug therapy (ATD) are the two most commonly used treatments. The United States chooses radioactive iodine as the first-line treatment option, while most European and Asian countries choose ATD as the first-line treatment option. Liu Changjiang, Department of Nuclear Medicine, Xinyi People’s Hospital In most areas of China, ATD is the first-line treatment option, and radioactive iodine is only used when patients are ineffective in applying ATD therapy or experience severe side effects after ATD therapy, one of the main reasons being the high incidence of hypothyroidism after radioactive iodine therapy. Since the application of radioactive iodine in the treatment of Graves’ hyperthyroidism, the search for an ideal dosing regimen that would ensure a high cure rate and reduce the incidence of hypothyroidism has been a disappointing one. The fixed-dose method and the calculated-dose method are the two treatment options for Graves’ hyperthyroidism. 1. Fixed-dose method: Yau JS, Chu KS, Li JK, Chan KW, Lau IT
JK, Chan KW, Lau IT, Yum SW, et al. Usage of a fixed dose of radioactive iodine
for the treatment of hyperthyroidism: one-year outcome in a regional hospital
Hong Kong Med J 2009;15:267C273.) with a fixed dose of 131 iodine (5, 6, 8, and 10 mCi) for hyperthyroidism. 1-year follow-up: 41% of patients had normalized thyroid function, 22% had hypothyroidism, and 37% remained hyperthyroid. Sisson JC, Avram AM,
Rubello D, Gross MD. Radioiodine treatment of hyperthyroidism: fixed or
calculated doses; intelligent design or science? Eur J Nucl Med Mol Imaging
(2007; 34:1129C1130.) A comparative study of the efficacy of treatment with the fixed dose method in two groups showed a higher treatment success rate (normalization of thyroid function or hypothyroidism) in patients applying 10mCi than in those with 5mCi (84.6 vs. 66.6%). Sisson considered it in terms of ALARA (as low as reasonably
2. Calculated dose method Markovic V applied the Marinelli formula to calculate the dose of iodine administered, and the planned amounts were randomly set at 100, 120, and 200 Gy. Ustun F applied the formula described in the textbook and set the planned dose at 120 μCi/g of thyroid tissue, and after a median follow-up period of 28 months, 26% of patients had normalized thyroid function and 22% had hypothyroidism. 3. The best outcome after individual dose therapy is normalization of thyroid function without hypothyroidism or persistent hyperthyroidism. The fixed-dose method and the calculated-dose method cannot guarantee both a high rate of normalization of thyroid function and a low incidence of hypothyroidism. Therefore, the aim of hyperthyroidism treatment is to treat hyperthyroidism in Europe and the United States, and the restoration of normal thyroid function and hypothyroidism after treatment are both successful treatments, because hyperthyroidism can cause complications in the cardiovascular, neurological and skeletal systems that are difficult to deal with, while hypothyroidism is the same as normal after oral thyroid hormone supplementation treatment. Our study showed that the incidence of normalization of thyroid function and the incidence of hypothyroidism after 131 iodine treatment were related to the age of the patient, the size of the thyroid gland and the duration of the disease, with a high incidence of hypothyroidism in those who were younger and had a small thyroid gland, and a higher incidence in those who were older, had a large thyroid gland and had a long duration of the disease and still presented with hyperthyroidism 1 year after treatment. According to the aforementioned study, we used an individual dose 131 iodine regimen, and during a mean follow-up period of 20.60±5.12 months, 75.5% of patients normalized their thyroid function, while the incidence of hypothyroidism was 6.1%, and 18.4% of patients remained hyperthyroid.