There are many causes of solid thyroid nodules, which are commonly found in the following: First, lack of thyroxine material, most commonly environmental iodine deficiency, such as endemic goiter, can be improved by eating iodized salt and consuming more iodine-rich foods, such as kelp and seafood. Secondly, increased thyroxine requirement is common in women during puberty and pregnancy. If there is hypothyroidism, it can be improved by taking oral levothyroxine sodium tablets, etc. Third, dysfunction of thyroxine synthesis and secretion, such as Hashimoto’s thyroiditis, diffuse goiter, etc. If a solid thyroid nodule is present, it is necessary to go to the hospital to improve the relevant examination to see the specific cause and determine the nature of the good and bad.