The need for treatment of a thyroid nodule that has grown 4 mm in a year depends on whether the patient has abnormal thyroid function, whether it produces symptoms of pressure, and whether the nodule has become malignant. Treatment is usually required for these conditions. If the thyroid nodule grows 4mm in a year and the thyroid ultrasound shows malignant tendency such as unclear boundaries and abundant blood flow signals in the nodule, we need to consider puncture biopsy, and then surgical resection is needed once malignancy is diagnosed. Moreover, if the nodule is too large, surgical resection should be considered if there is pressure on the nodule. In addition, if there is hypothyroidism, hyperthyroidism and other abnormalities of the thyroid gland, treatment is also needed. Hyperthyroidism can be treated with antithyroid drugs such as propylthiouracil or iodine radiation therapy, and hypothyroidism needs to be treated with levothyroxine sodium tablets. If the above conditions are not present, treatment is usually not needed and follow-up examinations are sufficient. If you have a thyroid nodule that has grown 4mm in a year, we recommend that you go to the hospital and ask your doctor to determine if you need treatment.