1, what is hypothyroidism (hypothyroidism for short)? Answer: Hypothyroidism (hypothyroidism for short) refers to a group of metabolic disorders characterized by a lack of thyroid hormones or insufficient biological effects due to different reasons, and is a more common endocrine disease characterized by metabolic and multi-system dysfunction. With the change of life rhythm, the increase of dietary iodine content and the aggravation of environmental pollution, the incidence of this disease is obviously rising trend. 2010 China’s top ten cities ≥ 20 years old people’s prevalence of thyroid disease epidemiological survey shows that: clinical hypothyroidism prevalence rate of 0.9%. 2.What are the categories of hypothyroidism and what are the possible causes? Answer: Classified according to the location of the lesion: (1) primary hypothyroidism: hypothyroidism caused by the lesion of the thyroid gland itself, this kind of hypothyroidism accounts for more than 95% of all hypothyroidism. The causes of primary hypothyroidism include autoimmunity, thyroid surgery and 131I treatment for hyperthyroidism, which account for more than 91% of all cases. (2) Central hypothyroidism or secondary hypothyroidism: hypothyroidism caused by hypothalamus and pituitary pathology resulting in a decrease in the production and secretion of thyrotropin-releasing hormone (TRH) or thyrotropin-stimulating hormone (TSH). (3) Thyroid hormone resistance syndrome: hypothyroidism caused by impaired realization of the biological effects of thyroid hormones in peripheral tissues. Classification according to the cause of the lesion: for example, pharmacological hypothyroidism (the most common drugs causing hypothyroidism, in addition to iodine, lithium carbonate for the treatment of manic-depressive disorder and amiodarone for the treatment of cardiac arrhythmia); hypothyroidism after surgery or 131I treatment; idiopathic hypothyroidism; hypothyroidism after surgery for pituitary gland or hypothalamus tumors, and so on. According to the degree of hypothyroidism classification: clinical hypothyroidism and subclinical hypothyroidism. 3.What is subclinical hypothyroidism? A: It refers to the serum TSH level is higher than the upper limit of normal value, and the FT4 level is normal. 2010 epidemiological survey on the prevalence of thyroid diseases among people ≥20 years old in ten major cities in China shows that the prevalence of subclinical hypothyroidism is 5.6%. The prevalence of subclinical hypothyroidism is 5.6%. The prevalence of hypothyroidism increases with age, and it is more common in women. 4.Who is prone to hypothyroidism? Answer: The high-risk groups of hypothyroidism include: (1) people with personal history and (or) family history of thyroid disease; (2) people with history of goiter and (or) surgical resection of the thyroid gland and (or) radiation iodine therapy or head and neck radiation therapy; (3) people with personal history and family history of autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, dry syndrome, vitiligo, type 1 diabetes mellitus, etc.; (4) people with increased serum TSH or increased serum TSH or increased serum diabetes mellitus; (5) people with increased serum TSH or increased serum TSH or increased serum TSH or increased serum TSH; (6) people with high risk for hypothyroidism. TSH or positive serum thyroid autoantibodies.