title: Iodine Status and Prevalence of Thyroid Disorders After Introduction of Mandatory Universal Salt Iodization for 16 Years in China: A Cross-Sectional Study in 10 Cities.
abstract: The goal of eliminating iodine deficiency worldwide was successfully achieved in China after the implementation of a mandatory universal salt iodization program for the last 16 years. Thus, China has been assessed as a country with more than adequate iodine levels. This survey aimed to investigate the current iodine status in China and the effects of an increased iodine intake on the spectrum and prevalence of thyroid disorders.
  
  
  
  A total of 15,008 adult subjects from 10 cities in eastern and central China were investigated. Serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb), and urine iodine concentration (UIC) were measured, and an ultrasonography of the thyroid was performed in all subjects. Free thyroxine (fT4) and free triiodothyronine (fT3) levels were only measured if the serum TSH was outside the normal range.
  
  
  
  The median UIC values were 197 μg/L in school-age children (SAC) and 205 μg/L in a cohort population. Six cities were classified as regions with adequate iodine intake (AII), and four cities as regions with more than adequate iodine intake (MTAII), according to median SAC UIC. The prevalence of clinical hypothyroidism, subclinical hypothyroidism, and positive thyroid antibodies was significantly higher in MTAII cities than it was in AII cities. Moreover, the prevalence of clinical hyperthyroidism (1.1% vs. 0.8%, p = 0.033) and Graves' disease (0.8% vs. 0.5%, p = 0.019) also significantly increased in MTAII cities. Compared with a five-year prospective study conducted in 1999, the prevalence of goiter significantly decreased (2.9% vs. 5.02%, p = 0.001), but there was a significant increase in thyroid nodules (12.8% vs. 2.78%, p = 0.001). The prevalence of subclinical hypothyroidism (16.7% vs. 3.22%), positive TPOAb (11.5% vs. 9.81%), and positive TgAb (12.6% vs. 9.09%) significantly increased, while no changes were seen in clinical hyperthyroidism, subclinical hyperthyroidism, or Graves' disease.
  
  
  
  The goal of eliminating iodine deficiency has been successfully achieved in China. However, the prevalence and spectrum of thyroid disorders has increased, reflecting possible adverse effects of increased iodine intake.
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Zhongyan
authors.initials: Z
authors.lastname: Shan
authors.affiliation: 2 Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology , Wuhan, China .
authors.forename: Lulu
authors.initials: L
authors.lastname: Chen
authors.affiliation: 3 Department of Endocrinology, Beijing Union Medical College Hospital , Beijing, China .
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Lian
authors.affiliation: 4 Department of Endocrinology, Jiangsu Province Hospital on Integration of Chinese and Western Medicine , Nanjing, China .
authors.forename: Chao
authors.initials: C
authors.lastname: Liu
authors.affiliation: 5 Department of Endocrinology, First Affiliated Hospital of Medical College of Xi'an Jiaotong University , Xi'an, China .
authors.forename: Bingyin
authors.initials: B
authors.lastname: Shi
authors.affiliation: 6 Department of Endocrinology, Affiliated Hospital of Guiyang Medical College , Guiyang, China .
authors.forename: Lixin
authors.initials: L
authors.lastname: Shi
authors.affiliation: 7 Department of Endocrinology, West China hospital, Sichuan University , Chengdu, China .
authors.forename: Nanwei
authors.initials: N
authors.lastname: Tong
authors.affiliation: 8 Department of Endocrinology, The Ruijin Hospital of Shanghai Jiaotong University , Shanghai, China .
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.affiliation: 9 Department of Endocrinology, The Third Affiliated Hospital of Sun Yat-sen University , Guangzhou, China .
authors.forename: Jianping
authors.initials: J
authors.lastname: Weng
authors.affiliation: 10 Department of Endocrinology, The Provincial Hospital Affiliated to Shandong University , Ji'nan, China .
authors.forename: Jiajun
authors.initials: J
authors.lastname: Zhao
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Teng
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Yu
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Yaxin
authors.initials: Y
authors.lastname: Lai
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Weiwei
authors.initials: W
authors.lastname: Wang
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Chenyan
authors.initials: C
authors.lastname: Li
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Jinyuan
authors.initials: J
authors.lastname: Mao
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Yongze
authors.initials: Y
authors.lastname: Li
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Chenling
authors.initials: C
authors.lastname: Fan
authors.affiliation: 1 Department of Endocrinology and Metabolism, Key Laboratory of Thyroid Diseases in Liaoning Province, The First Hospital of China Medical University , Shenyang, China .
authors.forename: Weiping
authors.initials: W
authors.lastname: Teng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000097:blood; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000276:immunology; D007455:Iodine / Q000652:urine*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D011634:Public Health; D017673:Sodium Chloride, Dietary; D013954:Thyroglobulin / Q000276:immunology; D013959:Thyroid Diseases / Q000097:blood / Q000453:epidemiology* / Q000276:immunology / Q000652:urine; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D017673:Sodium Chloride, Dietary; C034024:iodized salt; D014284:Triiodothyronine; D013972:Thyrotropin; D013954:Thyroglobulin; D007455:Iodine; D007453:Iodide Peroxidase; D013974:Thyroxine