1. Masses in the thyroid gland are collectively called thyroid nodules and are the most common type of thyroid disorder. Nodules are found by palpation in about 3-7% of cases, while ultrasonography can reveal nodules in 20-76% of subjects. They are more common in women than in men (4:1) and are more common in middle-aged and older adults than in adolescents. Therefore, thyroid nodules are found quite often in women after middle age by ultrasonography. The majority of thyroid nodules are benign, with malignancy accounting for only 5%. And even malignant thyroid nodules are much less aggressive than lung cancer. Therefore, once a nodule is found, there is no need to panic and never to be rash. 3.The etiology of thyroid nodules is complex and is currently believed to be related to radioactive exposure, autoimmunity, genetics, iodine intake and other factors. 4.After finding a thyroid nodule, you should visit an endocrinologist. A detailed medical history will help to determine the nature of the nodule. For example, nodules with hyperthyroidism may be high-functioning adenomas or early stages of subacute thyroiditis and Hashimoto’s thyroiditis; nodules with hypothyroidism are usually late stages of subacute thyroiditis and Hashimoto’s thyroiditis; nodules with a history of neck radiation therapy in childhood or thyroid nodules in children from non-thyroid endemic areas have a high chance of malignancy; nodules with a family history of thyroid cancer have a high rate of malignancy; nodules that have existed for many years have a high rate of malignancy in the short term. The possibility of malignancy should be considered when nodules that have been present for many years increase in size painlessly and significantly in a short period of time. After nodules are found, some necessary biochemical tests should be done, including thyroid function, autoantibodies and tumor markers. Most patients with nodules have normal thyroid function, and those with TSH abnormalities are less likely to have malignant nodules. Thyroid-specific antibodies TRAb, TPOAb, and TGAb are meaningful for the diagnosis of thyroiditis and have no special significance for the differentiation of benign and malignant. Calcitonin and carcinoembryonic antigen are elevated in medullary thyroid carcinoma. High-resolution ultrasonography is highly sensitive in detecting thyroid nodules, but is not as specific in determining benign or malignant.