Hypothyroidism is also known as hypothyroidism. The causes of hypothyroidism include autoimmune thyroiditis, pituitary or hypothalamic diseases, treatment-induced hypothyroidism, and iodine overdose. 1. Autoimmune thyroiditis: for example, Hashimoto’s thyroiditis, in which the thyroid tissue is destroyed by antibodies, leading to hypothyroidism. 2. Pituitary or hypothalamic diseases: for example, pituitary tumors, pituitary inflammation, hypothalamic tumors, etc., which lead to hypothyroidism caused by the hypothalamus or the pituitary gland producing thyrotropin-releasing hormone (TRH) or the reduction of the secretion and synthesis of thyrotropin. 3. Excessive iodine: Excessive iodine can cause hypothyroidism in people with underlying thyroid disease. 4. Treatment-induced hypothyroidism: Surgical removal of the thyroid gland, radioactive iodine treatment, etc. can lead to excessive destruction of the thyroid tissue and cause hypothyroidism. It is advisable to seek medical attention if any of the above factors are present and symptoms of hypothyroidism are suspected.