Thyroid nodules are a common benign thyroid disorder, mostly seen in middle-aged women. Due to a relative deficiency of thyroid hormones in the body, the pituitary TSH secretion increases, resulting in repeated thyroid enlargement with various degenerative changes, and eventually nodules. There may be two types of nodules: those without hyperthyroidism and those with hyperthyroidism. A multinodular goiter with hyperthyroidism is called toxic multinodular goiter. Disease description Nodular goiter, also known as adenomatous goiter, actually refers to multiple nodules that form in the advanced stages of endemic goiter and sporadic goiter. The incidence is high, with reports of up to 4% of the population. Nodular goiter is caused by the patient’s long-term exposure to iodine deficiency or relative iodine deficiency and goiter-causing substances, resulting in diffuse enlargement of the thyroid gland. After a longer course of the disease, the follicular epithelium changes from generalized hyperplasia to focal hyperplasia, with degenerative changes in some areas, and finally nodules of different stages of development appear in the gland due to the repeated alternation of long-term proliferative and degenerative lesions. It is actually a late manifestation of the natural evolution of simple goiter. In patients with nodular goiter, some of the nodules may develop functional autonomy, called toxic nodular goiter or Plummer’s disease. In some nodular goiters, embryonal adenomas or papillary adenomas can form due to excessive proliferation of epithelial cells, and thyroid cancer can also form. Symptoms and signs 1. The patient has a long history of simple goiter. The age of onset is usually older than 30 years. There are more women than men. The enlargement of the thyroid gland varies in degree and is mostly asymmetric. The number and size of nodules vary, usually multiple nodules, but early on there may be only one nodule. The nodules are soft or slightly hard, smooth, and not painful 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 may cause pressure symptoms such as dyspnea, dysphagia and hoarseness. Acute bleeding within the nodule may result in a sudden increase in size and pain. When hyperthyroidism (Plummer’s disease) occurs in nodular goiter, patients have 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. Symptoms are often atypical in elderly patients. 3. The patient has a history of radiation, oral medication and family history, and whether the patient comes from a region where endemic goiter is endemic. In general, patients with a long history of nodular goiter, no pressure symptoms, and no symptoms of hyperthyroidism are often unconcerned and come to the clinic for examination when they unintentionally find a thyroid nodule. 4. If the nodule is a hot nodule, also known as a toxic nodule, the patient is mostly 40 to 50 years old or older, the nodule is moderately hard, there are symptoms of hyperthyroidism, and even atrial fibrillation and other arrhythmic manifestations, and if there is bleeding, there can be pain and even fever. In case of larger nodules, compression symptoms may occur, such as dysphonia, dyspnea, chest tightness, shortness of breath and irritating cough. 5. Patients with nodular goiter from iodine deficient areas may have low thyroid function, slowed heart rate, edema, rough skin and anemia. A small number of patients may become cancerous. Warm nodules are more common and can be treated with thyroid preparations, and the enlarged gland can be reduced in size. Cold nodules are less common, and those with clinical hypothyroidism can be treated with thyroid preparations, but often require surgery. The pathogenesis and causes of thyroid nodules are still unknown and are probably due to a combination of factors such as genetics, radiation, immunity, geographic and environmental factors, goiter-causing factors, iodine deficiency, chemical stimulation and endocrine changes. Goiter-causing substances include certain foods, drugs, water pollution, soil pollution and environmental pollution, etc. There is an epidemic of goiter with nodular goiter in iodine-deficient areas, and radioactive damage can cause cancer, but decades of experience and statistics after the application of 131Ⅰ treatment prove that the main side effect of radioactive 131Ⅰ treatment is not cancer, but low thyroid function, especially in the long term. In some patients with multinodular goiter, the TGA and TMA tests were found to have a positive rate of 54.7%, while the rate of single nodule positivity was 16.9%. Patients with nodular goiter have an inborn metabolic defect that results in compensatory overgrowth of the goiter. Lack of environmental intake of trace elements such as selenium, fluoride, calcium, chloride and magnesium. In conclusion, the pathogenesis of nodular goiter is complex and remains inexact and needs to be studied.