An enlarged thyroid gland is usually considered a goiter, which may be caused by simple goiter, Hashimoto’s thyroiditis and other conditions. An enlarged thyroid gland is an imaging manifestation of thyroid tissue under ultrasound. An enlarged thyroid gland can be classified as first-degree, second-degree, or third-degree enlargement, in which a goiter can be palpated in first-degree enlargement but cannot be detected on visual inspection, in second-degree enlargement, a goiter can be observed but does not exceed the inner edge of the sternocleidomastoid muscle, and in third-degree enlargement, the goiter can exceed the outer edge of the sternocleidomastoid muscle. Causes of goiter include simple goiter, Hashimoto’s thyroiditis, subacute thyroiditis, and Graves’ disease. It is advisable to visit a hospital for a doctor’s judgment in the case of goiter.