Simple goiter is an enlargement of the thyroid gland with normal thyroid function. It is a compensatory goiter due to various causes, not accompanied by obvious hyper- or hypothyroidism, also known as non-toxic goiter. The occurrence of simple goiter is mostly related to the following factors: 1. Iodine deficiency: The main reason is that iodine is an essential element for the synthesis of thyroid hormones. 2. Increased need for thyroid hormone: During special periods such as puberty, pregnancy and lactation, the need for thyroid hormone increases, causing pro-thyroid hormone to be secreted excessively for a long time, which can also contribute to goiter. 3. Enzyme defects that impair thyroid hormone synthesis and secretion: Some simple goiters occur due to congenital or acquired deficiencies of certain enzymes in the biosynthesis and secretion of thyroid hormones, such as iodide transport enzyme defects and peroxidase defects, which cause goiter. 4.Smoking and drugs: certain drugs such as iodide, fluoride and sulfonamides can interfere with and inhibit the synthesis of thyroid hormones through different mechanisms, affecting the synthesis of thyroid hormones and causing simple goiter; smokers can cause goiter because the inhalants contain thioglycolate, which is also a goiter-causing substance. 5. Other conditions such as cortisolism and acromegaly can also cause goiter, and recessive inherited congenital defects such as peroxidase or protein hydrolase deficiency can also cause goiter. In patients with simple goiter, the clinical manifestations vary in severity and disparity, but because their thyroid function is normal, no special treatment is usually required.