title: More than adequate iodine intake may increase subclinical hypothyroidism and autoimmune thyroiditis: a cross-sectional study based on two Chinese communities with different iodine intake levels.
abstract: OBJECTIVE
  With the introduction of iodized salt worldwide, more and more people are exposed to more than adequate iodine intake levels with median urinary iodine excretion (MUI 200-300 μg/l) or excessive iodine intake levels (MUI >300 μg/l). The objective of this study was to explore the associations between more than adequate iodine intake levels and the development of thyroid diseases (e.g. thyroid dysfunction, thyroid autoimmunity, and thyroid structure) in two Chinese populations.
  
  
  METHODS
  A population-based cross-sectional study was conducted in two areas in which people are exposed to different levels of iodine intake (Rongxing, MUI 261 μg/l; Chengshan, MUI 145 μg/l). A total of 3813 individuals were recruited by random sampling. Thyroid hormones, thyroid autoantibodies in serum, and iodine levels in urine were measured. B-mode ultrasonography of the thyroid was also performed for each participant.
  
  
  RESULTS
  The prevalence of subclinical hypothyroidism was significantly higher for subjects who live in Rongxing than those who live in Chengshan (5.03 vs 1.99%, P<0.001). The prevalence of positive anti-thyroid peroxidase antibody (TPOAb) and positive anti-thyroglobulin antibody (TgAb) was significantly higher for subjects in Rongxing than those in Chengshan (TPOAb: 10.64 vs 8.4%, P=0.02; TgAb: 10.27 vs 7.93%, P=0.01). The increase in thyroid antibodies was most pronounced in the high concentrations of TPOAb (TPOAb: ≥500 IU/ml) and low concentrations of TgAb (TgAb: 40-99 IU/ml) in Rongxing.
  
  
  CONCLUSIONS
  More than adequate iodine intake could be a public health concern in terms of thyroid function and thyroid autoimmunity in the Chinese populations.
authors: Department of Endocrinology and Metabolism, The First Affiliated Hospital, China Medical University, No 155 Nanjing Bei Street, Heping District, Shenyang, People's Republic of China.
authors: Xiaochun
authors: X
authors: Teng
authors: Zhongyan
authors: Z
authors: Shan
authors: Yanyan
authors: Y
authors: Chen
authors: Yaxin
authors: Y
authors: Lai
authors: Jiashu
authors: J
authors: Yu
authors: Ling
authors: L
authors: Shan
authors: Xue
authors: X
authors: Bai
authors: Yuanbin
authors: Y
authors: Li
authors: Ningna
authors: N
authors: Li
authors: Zhidan
authors: Z
authors: Li
authors: Sen
authors: S
authors: Wang
authors: Qian
authors: Q
authors: Xing
authors: Haibo
authors: H
authors: Xue
authors: Lin
authors: L
authors: Zhu
authors: Xin
authors: X
authors: Hou
authors: Chenling
authors: C
authors: Fan
authors: Weiping
authors: W
authors: Teng
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001323:Autoantibodies / Q000097:blood; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004032:Diet; D005260:Female; D006042:Goiter / Q000453:epidemiology; D006801:Humans; D006980:Hyperthyroidism / Q000139:chemically induced / Q000453:epidemiology; D007037:Hypothyroidism / Q000139:chemically induced* / Q000453:epidemiology*; D007453:Iodide Peroxidase / Q000097:blood; D007455:Iodine / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D017673:Sodium Chloride, Dietary; D013954:Thyroglobulin / Q000097:blood; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000000981:diagnostic imaging; D013967:Thyroiditis, Autoimmune / Q000139:chemically induced* / Q000453:epidemiology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014463:Ultrasonography; D014881:Water Supply; 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