1. Etiology The etiology of nodular goiter is similar to that of simple goiter. Most of them are based on simple diffuse goiter, and due to repeated progression of the disease, the follicular epithelium is transformed from diffuse hyperplasia to focal hyperplasia, and degenerative changes appear in some areas. Finally, due to repeated alternation of long-term proliferative and degenerative lesions, nodules of different stages of development appear in the gland, which are actually a late manifestation of simple goiter. In patients with nodular goiter, 5-8% of them may develop toxic symptoms. Some nodular goiters, by overgrowth of epithelial cells, can form embryonal adenomas or papillary adenocarcinomas, or thyroid cancer. In this case, it is difficult to distinguish from thyroid adenoma or adenocarcinoma combined with simple goiter. 2. Clinical manifestations The patient has a long history of simple goiter. The age of onset is usually older than 30 years old, more women than men. The number and size of nodules vary, usually multiple nodules, but there may be only one nodule in the early stage. The nodules are soft or slightly hard, smooth and painless to the touch. Sometimes the nodules are not well-defined, and touching the surface of the thyroid gland only gives an irregular or lobulated sensation. The disease progresses slowly and most patients are asymptomatic. Larger nodular goiters can cause pressure symptoms, including difficulty breathing, difficulty swallowing, and hoarseness. Acute bleeding within the nodule may cause a sudden increase in size and pain. When hyperthyroidism occurs in nodular goiter, the patient has symptoms such as fatigue, weight loss, palpitations, arrhythmia, fear of heat and sweating, and agitation, but there is no local vascular murmur and tremor in the thyroid gland. The patient has a history of receiving radiation, oral medication, family history, and whether the patient is from a region where endemic goiter is endemic. In general, nodular goiter has a long history, no pressure symptoms, and no symptoms of hyperthyroidism, so patients often do not care and come to the clinic for examination when they unintentionally find a thyroid nodule. Some of them have endocrine function, which is clinically known as nodular hyperthyroidism, while others have no endocrine function, which is known as general nodular goiter, and some have hypofunction, which should be considered as possible thyroid tumor. The diagnosis of simple nodular goiter is generally not difficult, with a long medical history, mostly without pressure symptoms, and generally normal clinical manifestations, and its thyroid tissue can shrink to varying degrees when treated with thyroid preparations. The final diagnosis should rely on pathological examination to clarify the nature of the thyroid nodule, relying only on the general medical history, physical examination, laboratory tests or radionuclide examination can not make 100% judgment and diagnosis of malignant nodules. 5. Treatment Nodular goiter is a common endocrine disease. Most patients are asymptomatic, have a good prognosis, and can be observed and followed up. A small number of nodules can evolve into hyperthyroidism and malignancy. Generally simple nodular goiter, both single and multiple nodules, can be treated with thyroid preparations if they are warm or cold nodules. Give thyroid powder (tablets), divided into 1-2 oral doses daily. Or just use levothyroxine sodium tablets 1-2 times a day. Those whose enlarged nodules shrink after treatment may continue to use until they disappear completely. Those whose nodules do not disappear after treatment should be treated by removal of thyroid nodules and changes in thyroid function should be observed during treatment. Surgical treatment should also be the mainstay for those with functional autonomy of hot nodules, and postoperative changes in thyroid function should also be observed. Clinically, there are cases of thyroid adenomas that have been removed for more than 10 years and still recur, which can be treated surgically again. If the nodule does not shrink but grows rapidly and involves the surrounding tissues, it should be considered as malignant cancer and surgery should be sought as soon as possible. Surgical treatment is often a thorough clearance, and postoperative hypothyroidism is often present, which must be treated with lifelong thyroid hormone replacement. And there is a possibility of preventing recurrence. Thyroid nodules need to be identified as benign or malignant in nature, and by palpation and ultrasound are only the initial screening. The first step is to make a comprehensive assessment of the size of the nodule, the presence or absence of pain, and the speed of growth. If the growth rate is slow and the number of non-functioning nodules is small, a blood test will be performed. If low thyroid stimulating hormone is present, the nodule may be benign and can be treated with medication and reviewed regularly. If the nodule is suspected to be malignant, a thyroid puncture is recommended for early surgical treatment. In case of highly malignant undifferentiated thyroid cancer, distant metastasis exists at the time of diagnosis, so surgery alone is difficult to achieve the treatment purpose, so a comprehensive treatment method should be used. Western medical treatment for nodular goiter still lacks a large enough amount of evidence-based medical evidence, and treatment methods are not yet consistent. Drug therapy is less effective for nodular goiter, so treatment tends to favor surgical excision, but this can easily lead to overtreatment or cause counterproductive effects, resulting in hypothyroidism in patients.