Simple goiter refers to the enlargement of the thyroid gland caused by the proliferation of thyroid epithelial cells due to non-inflammatory and non-neoplastic reasons, without clinical abnormalities in thyroid function. The thyroid gland is where thyroid hormones are synthesized, and simple goiter accounts for about 5% of the normal population, with the incidence in women being 3 to 5 times higher than in men.
During ultrasound examination, the thyroid gland shows varying degrees of enlargement, but blood tests for thyroid function, including TT3, TT4, free T3, free T4, and thyroid-stimulating hormone (TSH) secreted by the hypothalamus and pituitary gland, all fall within the normal range. Therefore, there are no clinical symptoms of hyperthyroidism or hypothyroidism, only the presence of thyroid enlargement. This type of thyroid enlargement is referred to as simple goiter.