With the addition of thyroid examination items in recent years; or because of other diseases for physical examination doctors found; or do other tests such as CT, MRI, etc., thyroid nodules were found, so the number of patients gradually increased to see the doctor. Patients often ask why they have nodules. Here are some tips for you to know. The thyroid gland is the largest endocrine gland in the body and is divided into two lobes, the left and right, and an isthmus that connects the two lobes, and sometimes a long, thin cone-like lobe that extends upward from the isthmus between the two lobes. It is located at the front of our neck on both sides, and behind it is the trachea. Normally, the thyroid gland is so small that it cannot be felt in the neck. What is the role of the thyroid gland The main physiological function of thyroid hormones secreted by the thyroid gland in the human body is to promote tissue oxidation and thermogenesis; in addition, it also plays a role in regulating or promoting the growth and maturation of the human body, the functional state of the nervous system and cardiovascular system, and the metabolism of certain substances. The physiological significance of the thermogenic effect of thyroid hormones is to maintain the body’s energy metabolism at a certain level and to regulate the stability of body temperature. When the external temperature decreases, the secretion of thyroid hormones increases and the body produces more heat to keep the body temperature from falling. Conversely, when the temperature rises, thyroid hormone secretion decreases, which reduces heat production and ensures that the body temperature is not affected by the increase in external temperature. Thyroid hormones have a significant impact on the body’s material metabolism, water and electrolyte metabolism. Thyroid hormones are an important factor in the growth, development and maturation of the body, and the younger the age, the more pronounced the influence of thyroid hormones on growth and development. In children with an underactive thyroid gland, growth is halted and growth can resume after thyroxine is given. The effects of thyroid hormones on growth and development are most severe in the bone and nervous systems. During the embryonic or neonatal period, thyroid hormone deficiency damages brain tissue much more severely than other tissues. Such children are not only short in stature, but also have more severe brain developmental disorders and are mentally retarded and stupid. The effect of thyroid hormones on the gonads: In women, insufficient or excessive thyroid function can cause ovarian damage and irregular sexual cycles, even amenorrhea and infertility. Thyroid hormones also have a role in promoting lactation. In males, when the thyroid gland is under- or over-functioning, testicular function is easily disrupted. It is more likely to be impaired in early childhood, manifesting as: male genitalia are underdeveloped, testes do not descend, and paraphilias do not appear. Reduced sperm production and impotence occur in the presence of hyperthyroidism. Iodine is necessary for the synthesis of thyroid hormones, and iodine deficiency can cause insufficient synthesis of thyroid hormones, accompanied by compensatory goiter such as endemic goiter. However, large amounts in excess of physiological needs can also cause thyroid dysfunction. Iodine enters the body mainly with food and water, and the amount of iodine consumed in the diet varies greatly depending on dietary habits and the iodine content of local soil and water. The thyroid gland is an important organ for iodine uptake. The normal thyroid gland contains a large amount of iodine, accounting for 80-90% of the total iodine in the body, and the daily iodine uptake and release from the thyroid gland are in balance, with a normal adult daily iodine requirement of 120-150 micrograms. And the daily release of iodine is also comparable. Only a small portion of the iodine intake is taken up by the thyroid gland and most of it is excreted through the kidneys. Under normal dietary conditions, our daily iodine intake through food is sufficient to meet our physiological needs. During breastfeeding, a significant amount of iodine is secreted from breast milk for the infant’s needs. The concentration of iodide in breast milk can be more than ten to several dozen times higher than in blood plasma. Therefore, the thyroid gland is also an important endocrine gland in the human body and, like other organs, is subject to deformities, injuries, inflammation, tumors and functional abnormalities. The most important ones are functional abnormalities and tumors. So far, the causes and pathogenesis of thyroid nodules or tumors are not clear, but may be related to the following factors: 1. 2. Radiation: Statistics show that 20-30% of children and adolescents with thyroid cancer have a history of radiation exposure to the neck. 3. Iodine deficiency and to goiter substances: The incidence of thyroid cancer in endemic goiter areas is significantly higher than that in non-endemic goiter areas, and our Yunnan Province belongs to endemic goiter areas. It has also been shown that low iodine diet can lead to goiter, goiter and adenocarcinoma in mice. The mechanism may be the combined effect of iodine deficiency and goiter substances, resulting in reduced synthesis and secretion of thyroxine, which in turn causes excessive TSH secretion by the pituitary gland and long-term hyperplasia of the thyroid follicular epithelium to form nodules and eventually cancer. Whether iodine deficiency is one of the causes of thyroid cancer is yet to be confirmed. 4. Thyroid autoimmune diseases: Hashimoto’s thyroiditis and hyperthyroidism both have a higher chance of combining with thyroid cancer than other pathologies, which may be related to the autoimmune disorder of the body.