The causes of thyroid nodules are complex. Therefore, there is no definite conclusion on the exact cause of thyroid nodules, but it is believed that the appearance of thyroid nodules is related to the following five factors. Radiation exposure” is an important causative factor for thyroid cancer. Some data show that the incidence of thyroid cancer is higher in individuals who received 10-1000 rad of radiation exposure during childhood. Autoimmune thyroiditis, also known as chronic thyroiditis and Choban’s thyroiditis, predisposes to thyroid nodules. 3.Heredity Except for familial medullary carcinoma, there is no evidence that other thyroid cancers are hereditary, only about 7% of patients with papillary thyroid carcinoma may have family genetic tendency. 4.Iodine deficiency Severe iodine deficiency can cause endemic goiter. Excessive iodine intake can also cause various thyroid diseases, such as abnormal thyroid function and thyroid nodules.