Diffuse thyroid changes, also known as diffuse thyroid lesions, are a manifestation under thyroid imaging and may be caused by Hashimoto’s thyroiditis and Graves’ disease. Diffuse thyroid lesions are lesions that involve most or all of the thyroid tissue, and it is recommended that they be combined with thyroid function tests to determine whether abnormalities such as hypothyroidism or hyperthyroidism are present. The presence of positive serum thyrotropin receptor antibodies with decreased serum thyrotropin and increased thyrotropin levels suggests Graves’ disease, while the presence of elevated serum thyroid peroxidase and thyroglobulin antibodies with decreased serum thyrotropin and increased thyrotropin levels suggests a high likelihood of Hashimoto’s thyroiditis. In the case of diffuse thyroid lesions, it is recommended to go to the hospital and ask the doctor to make a judgment and determine the cause of the disease.