The prevalence of overt hypothyroidism in the general population ranges between 0.2% and 5.3% in Europe.[4]Taylor PN, Albrecht D, Scholz A, et al. Global epidemiology of hyperthyroidism and hypothyroidism. Nat Rev Endocrinol. 2018 May;14(5):301-16.
http://www.ncbi.nlm.nih.gov/pubmed/29569622?tool=bestpractice.com
The incidence of primary hypothyroidism in the UK is estimated to be 0.41% per year for women and 0.06% per year in men.[5]Vanderpump MP, Tunbridge WM, French JM, et al. The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham survey. Clin Endocrinol. 1995 Jul;43(1):55-68.
http://www.ncbi.nlm.nih.gov/pubmed/7641412?tool=bestpractice.com
In the US, the prevalence of overt primary hypothyroidism is 0.3%, and of sub-clinical hypothyroidism is 4.3%.[6]Hollowell JG, Staehling NW, Flanders WD, et al. Serum TSH, T(4) and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). J Clin Endocrinol Metab. 2002 Feb;87(2):489-99.
https://academic.oup.com/jcem/article/87/2/489/2846568
http://www.ncbi.nlm.nih.gov/pubmed/11836274?tool=bestpractice.com
The prevalence of overt and sub-clinical hypothyroidism is higher in white people (5.1%) than in black people (1.7%), or Hispanic people (4.2%).[6]Hollowell JG, Staehling NW, Flanders WD, et al. Serum TSH, T(4) and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). J Clin Endocrinol Metab. 2002 Feb;87(2):489-99.
https://academic.oup.com/jcem/article/87/2/489/2846568
http://www.ncbi.nlm.nih.gov/pubmed/11836274?tool=bestpractice.com
The prevalence of hypothyroidism is higher in women and increases with age.[4]Taylor PN, Albrecht D, Scholz A, et al. Global epidemiology of hyperthyroidism and hypothyroidism. Nat Rev Endocrinol. 2018 May;14(5):301-16.
http://www.ncbi.nlm.nih.gov/pubmed/29569622?tool=bestpractice.com
It ranges from 4% in women aged 18 to 24 years, to 21% in women older than 74 years, and 3% to 16% in men of the same age groups.[7]Canaris GJ, Manowitz NR, Mayor G, et al. The Colorado thyroid disease prevalence study. Arch Intern Med. 2000 Feb 28;160(4):526-34.
http://www.ncbi.nlm.nih.gov/pubmed/10695693?tool=bestpractice.com
Differences in iodine status affect the prevalence of hypothyroidism as both severe iodine deficiency and iodine excess may cause hypothyroidism.[1]Chaker L, Bianco AC, Jonklaas J, et al. Hypothyroidism. Lancet. 2017 Sep 23;390(10101):1550-62.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6619426
http://www.ncbi.nlm.nih.gov/pubmed/28336049?tool=bestpractice.com
Iodine deficiency is a major cause of hypothyroidism worldwide.[8]American Association of Clinical Endocrinologists; American Thyroid Association. Clinical practice guidelines for hypothyroidism in adults: cosponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association. Endocr Pract. 2012 Nov-Dec;18(6):988-1028.
https://www.endocrinepractice.org/article/S1530-891X(20)43030-7/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/23246686?tool=bestpractice.com
While less common in the developed world, iodine intake is inadequate in some European countries, including Germany, Norway, and Finland.[9]Zimmermann MB, Andersson M. Global endocrinology: global perspectives in endocrinology: coverage of iodized salt programs and iodine status in 2020. Eur J Endocrinol. 2021 Jun 10;185(1):R13-21.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8240726
http://www.ncbi.nlm.nih.gov/pubmed/33989173?tool=bestpractice.com
Global efforts to universally iodise salt have diminished the magnitude of this problem.[10]Han X, Ding S, Lu J, et al. Global, regional, and national burdens of common micronutrient deficiencies from 1990 to 2019: a secondary trend analysis based on the Global Burden of Disease 2019 study. EClinicalMedicine. 2022 Feb;44:101299.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8850322
http://www.ncbi.nlm.nih.gov/pubmed/35198923?tool=bestpractice.com
[11]Dold S, Zimmermann MB, Jukic T, et al. Universal salt iodization provides sufficient dietary iodine to achieve adequate iodine nutrition during the first 1000 days: a cross-sectional multicenter study. J Nutr. 2018 Apr 1;148(4):587-98.
https://www.sciencedirect.com/science/article/pii/S0022316622108102?via%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/29659964?tool=bestpractice.com
However, iodine intake is still low in many countries and in high-risk individuals, such as pregnant women.[12]Lazarus JH. The importance of iodine in public health. Environ Geochem Health. 2015 Aug;37(4):605-18.
https://www.doi.org/10.1007/s10653-015-9681-4
http://www.ncbi.nlm.nih.gov/pubmed/25663362?tool=bestpractice.com
[13]Caldwell KL, Pan Y, Mortensen ME, et al. Iodine status in pregnant women in the National Children's Study and in US women (15-44 years), National Health and Nutrition Examination Survey 2005-2010. Thyroid. 2013 Aug;23(8):927-37.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3752509
http://www.ncbi.nlm.nih.gov/pubmed/23488982?tool=bestpractice.com
IGN: global scorecard of iodine nutrition in 2021
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