What is a thyroid nodule Thyroid nodules are the most common type of thyroid condition, and their incidence is increasing every year. Epidemiological surveys show that the prevalence of palpable thyroid nodules in adults is 4-8%, and the detection rate of thyroid nodules in the United States is reported to be as high as 19-67%, with women and elderly populations being more common. Thyroid nodules are divided into two categories: benign and malignant. Benign lesions account for about 95% and malignant lesions account for only about 5% (91% of which are differentiated thyroid cancer, 5% are medullary thyroid carcinoma, and only 3% are undifferentiated thyroid cancer). Possible factors of malignancy of thyroid nodules The current consensus academic opinion suggests that the factors with a high probability of malignant thyroid nodules are: (1) having a palpable thyroid nodule at the age of <20 years or >70 years; (2) having a history of head and neck or whole body radiation exposure (radiation therapy for tumor or bone marrow transplantation); (3) having a first-degree relative with thyroid cancer; (4) having a fast-growing nodule; (5) having hoarseness; (6) having vocal cord paralysis; (7) Enlarged and fixed lymph nodes in the neck ipsilateral to the nodule. Treatment of malignant thyroid nodules The current consensus is to perform a total or near-total thyroidectomy, followed by radioiodine removal of residual thyroid tissue and thyroid hormone suppression therapy. If the nodule increases in size (15% increase in volume or 20% increase in diameter), repeat puncture, especially ultrasound-guided puncture, will be performed at 6-12 month intervals and the treatment will be decided according to the results. The effect of thyroxine on benign thyroid nodules: in areas of low iodine intake, benign nodules may shrink when levothyroxine (L-T4) is taken and TSH is suppressed; in areas of adequate iodine supply, no such effect is seen. The consensus opinion does not recommend the routine use of thyroxine suppression therapy for benign thyroid nodules. Management of thyroid nodules in children Thyroid nodules in children are less common than in adults, have a malignancy rate equal to or higher than that of adults, and are evaluated and treated in the same way as adults (clinical evaluation, laboratory evaluation, evaluation of ancillary tests, etc.). Management of thyroid nodules in pregnancy The evaluation of thyroid nodules in pregnancy is the same as in non-pregnant women, except that thyroid nuclei imaging cannot be performed. If thyroid nodules are normal or hypothyroid with thyroid nodules, FNAC should be performed; if TSH levels are still suppressed after the third trimester, ultrasonography and FNAC should be performed after delivery; if malignant nodules are found in early pregnancy, ultrasound monitoring and nodules grow, surgery at 24 weeks of pregnancy may be an option; if nodules are stable in size by mid-pregnancy, or if malignant nodules are found in late pregnancy, surgery after delivery may be an option.