TG and metabolic syndrome: To investigate the epidemiological characteristics of hypothyroidism in Qinghai Province, analyze its related influencing factors, establish the normal reference range of thyroid function, and explore the relationship between thyroid hormone (THs), thyroid stimulating hormone (TSH) and metabolic syndrome (MS) in Qinghai population within the normal range, so as to provide some scientific basis for the prevention and treatment of hypothyroidism in Qinghai Province.