Effect of iodine intake on serum TSH Level and thyroid antibodiesFA cross-sectional study of ten cities in China

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 432-458-Thyroid Autoimmunity
Basic/Clinical
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-447
Weiping Teng*1, Lulu Chen2, Xiaolan Lian3, Chao Liu4, Zhongyan Shan5, Bingyin Shi6, Lixin Shi7, Nanwei Tong8, Jianping Weng9, Shu Wang10, Jiajun Zhao11, Xiaochun Teng12, Xiaohui Yu13, Yaxin Lai5, Chenyan Li5, Weiwei Wang5, Jinyuan Mao5 and Chenling Fan5
1Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, 2The Cooperate Hospital of Huazhong science and technology University, Wuhan, China, 3Department of Endocrinology, The Beijing Cooperate Hospital, Beijing, China, 4Jiangsu Hosp of Integrated, Nanjing, Jiangsu Province, 5Department of Endocrinology and Key Laboratory of Endocrine diseases in Liaoning Province , The first Hospital of China Medical University, Shenyang,China, 6Department of Endocrinology, Xi'an, 7Department of Endocrinology, The First Hospital of Guiyang Medical School, Guiyang, China, 8West China Hospital, Chengdu, Sichuan Province, 9Department of Endocrinology, The third Hospital of Zhongshan University, Guangzhou, China, 10Ruijin Hosp, Shanghai, 11Shandong Provincial Hosp, Jinan Shandong, 12Department of Endocrinology and Key Laboratory of Endocrine diseases in Liaoning Province , The first Hospital of China Medical University, Shenyang, China, 13Department of Endocrinology and Key Laboratory of Endocrine diseases in Liaoning Province , The first Hospital of China Medical University, Shenyang,China, Shenyang
Context For six years there has been an excessive intake of iodine among the Chinese population and a more than adequate intake of for ten years, since 1996. However, changes in the prevalence of thyroid disorders among the population after long-term iodine fortification has not been clearly verified.

Objective To determine the current prevalence of thyroid disorders in China and to assess the association of serum TSH and antithyroid antibodies with iodine intake.

Design and setting A cross-sectional study was conducted in ten cities in China between May, 2010 and May, 2011.

Participates A total of 15,008 randomly chosen subjects from one or two communities in each city were studied. Iodine concentration in urine, from a total of 80 school-age children from each city, was also tested.

Main Outcome Measures Palpation and B-mode ultrasonography of the thyroid were performed, and urine iodine levels and serum levels of TSH, TPOAb and TgAb were measured in all participants. FT4 and FT3 were measured in individuals who had abnormal TSH concentrations.

Results The prevalence of overt hypothyroidism, subclinical hypothyroidism, overt hyperthyroidism as well as positive TPOAb and TgAb were significantly higher in regions with excessive iodine intake than in regions with adequate iodine intake. The serum TSH levels were notably higher than reported previously. The median TSH level was 2.40 mIU/liter (0.76–6.92 mIU/liter) in the reference population. Median of TSH from a subpopulation (n=2502) was found to increase over time from 1.17 mIU/liter in 1999 to 1.96 mIU/liter in 2011 (P>0.001) with a change in the median urine iodine (MUI) from 143.4 μg/liter to 194.5 μg/liter. The prevalence of positive thyroid antibodies also rose from 4.9% in 1999 to 7.2% in 2011 for TPOAb (P=0.04) and from 5.5% to 8.4% for TgAb (P=0.02).

Conclusions  More than adequate iodine intake was found to be associated with increased prevalence of most thyroid disorders. The notably high TSH levels detected in the Chinese population may be related to long-term iodine fortification and aggravated thyroid autoimmunity. The significance of high TSH values in Chinese population merits further study.

Nothing to Disclose: WT, LC, XL, CL, ZS, BS, LS, NT, JW, SW, JZ, XT, XY, YL, CL, WW, JM, CF

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: This sdudy was supported by ‡@The International Exchange and Cooperation Foundation of Ministry of Health of The People’s Republic of China; ‡AGuanghua Sicence and Technology Foundation of China.