Hyperthyroidism can be divided into the following categories according to the cause: 1. Thyroid hyperthyroidism The cause is in the thyroid gland itself. These include: diffuse toxic goiter (Graves’ disease); autonomous high-functioning thyroid nodules; multinodular goiter with hyperthyroidism; neonatal hyperthyroidism; iodine hyperthyroidism; and follicular thyroid cancer. 2. Pituitary hyperthyroidism There are pituitary tumors (TSH cell tumors) causing hyperthyroidism and non-pituitary tumors causing hyperthyroidism. 3.Tumor associated hyperthyroidism Some malignant carcinomas secrete TSH-like substances and cause hyperthyroidism. Such as choriocapillary epithelial carcinoma with hyperthyroidism, staphyloma with hyperthyroidism, lung cancer and gastrointestinal (stomach, colon, pancreas) cancer with hyperthyroidism. 4. Ovarian goiter with hyperthyroidism. There are two types of symptomatic hyperthyroidism: one is thyroiditis, including subacute thyroiditis; Hashimoto’s thyroiditis; and radiation thyroiditis. The second is pharmacogenic hyperthyroidism. Among the many types of hyperthyroidism mentioned above, diffuse toxic goiter (Graves’ disease) and hyperthyroidism with thyroiditis are the most common.