There are many causes of thyroid disease, including iodine-derived factors, genetic factors, autoimmune factors and medical factors. 1. Iodine-derived factors. Iodine is an important raw material for synthesizing thyroid hormones, and too much or too little iodine intake may cause abnormalities in the body. 2. Genetic factors. Some types of thyroid disorders (such as hyperthyroidism) occur in female patients and are usually hereditary. 3. Autoimmune factors. Autoimmune damage is the most common cause of hypothyroidism, including Hashimoto’s thyroiditis, atrophic thyroiditis, and postpartum thyroiditis. 4. Medical factors. Including improper use of medication, or after thyroidectomy, may lead to abnormal thyroid function. For example, overdose of levothyroxine may lead to hyperthyroidism, and hypothyroidism may occur after total thyroidectomy. When thyroid disease occurs, you should actively cooperate with your doctor for regular follow-up or treatment with medication or surgery.