The shrinkage of the thyroid gland may be caused by physiological factors, pathologic factors, such as atrophic thyroiditis, recurrent subacute thyroiditis and other reasons. 1. Physiological factors: with age, the thyroid gland will undergo degenerative changes and gradually decrease in size, usually without other obvious clinical manifestations. In this case, regular checkups are sufficient, and no medication is needed. 2. Pathological factors: such as atrophic thyroiditis, recurrent subacute thyroiditis and other causes. These patients need to be treated under the guidance of a doctor. Atrophic thyroiditis: related to autoimmune abnormalities, such patients have TSH receptor stimulation blocking antibodies, which can block the role of TSH to make the thyroid gland atrophy. (2) Recurrent subacute thyroiditis: recurrent attacks of subacute thyroiditis caused by influenza viruses lead to an increase in the fibrous tissue of the thyroid gland, resulting in contracture of the thyroid gland and shrinkage of the thyroid gland. When patients find that the thyroid gland is shrinking, they should go to the hospital in time to improve the examination, and then carry out treatment after the cause of the disease is clarified. When there is a change in the condition, consult a doctor promptly.