The two most important tests to distinguish primary hyperthyroidism from Hashimoto’s hyperthyroidism are thyroid receptor antibodies, thyroglobulin antibodies, and thyroid peroxidase antibodies, and ultrasound. In primary hyperthyroidism, the patient’s thyroid receptor antibodies are significantly elevated, while thyroglobulin and peroxidase antibodies are normal or high. Hashimoto’s hyperthyroidism is characterized by normal levels of thyroid receptor antibodies and significantly elevated levels of thyroglobulin and peroxidase antibodies. In addition, an ultrasound examination of the thyroid gland will reveal a mildly enlarged thyroid gland and a coarse, uneven echogenicity of the thyroid gland. These two tests can be used to differentiate the two diseases.