The causes of hyperthyroidism include diffuse toxic goiter (Graves’ disease), long-term massive iodine intake or iodine-containing drugs. 1. Graves’ disease: it is the most common cause of hyperthyroidism. This kind of patients can produce specific antibodies, i.e. thyroid hormone receptor antibodies, which can cause thyroid cell hyperplasia and excessive production of thyroid hormone and eventually lead to hyperthyroidism. 2. Long-term massive iodine intake or iodine-containing drugs: Hyperthyroidism is induced by long-term iodine intake or iodine supplementation in people exposed to iodine-deficient environments for a long time. In addition, stress, bacterial or viral infections may also induce hyperthyroidism. Patients diagnosed with hyperthyroidism should actively cooperate with their doctors for treatment.