The causes of hypothyroidism include autoimmune thyroiditis, treatment-induced hypothyroidism, medication that affects the thyroid, iodine overdose or iodine deficiency. 1. Autoimmune thyroiditis, such as Hashimoto’s thyroiditis, in which antibodies attack the thyroid tissue, leading to hypothyroidism. 2. Treatment-induced hypothyroidism: after thyroid surgery, radioactive iodine treatment of the thyroid gland, etc., which can destroy thyroid tissue and cause hypothyroidism. 3. Taking drugs that affect the thyroid gland: drugs such as amiodarone and sodium para-aminosalicylate may cause hypothyroidism. 4. Iodine overdose or iodine deficiency: Iodine overdose may cause hypothyroidism in patients with underlying thyroid diseases such as Hashimoto’s thyroiditis. If any of the above factors are present, it is recommended to go to the hospital in time for treatment under the guidance of a doctor.