The Danish investigation on iodine intake and thyroid disease (DanThyr): history and implications

Line Tang Møllehave*, Nils Knudsen, Allan Linneberg, Inge Bülow Pedersen, Gitte Ravn-Haren, Anja Lykke Madsen, Allan Carlé, Charlotte Cerqueira, Anne Krejbjerg, Lone Banke Rasmussen, Lars Ovesen, Hans Perrild, Lena Bjergved Sigurd, Betina Heinsbæk Thuesen, Pernille Vejbjerg, Torben Jørgensen

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

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Abstract

Due to mild-to-moderate iodine deficiency in Denmark, health authorities initiated a voluntary iodine fortification (IF) program in 1998, which became mandatory in 2000. In line with recommendations from the World Health Organization, the Danish investigation on iodine intake and thyroid disease (DanThyr) was established to monitor the effect on thyroid health and disease. The program involved different study designs and followed two Danish sub-populations in the years before IF and up till 20 years after. Results showed that the IF was successfully implemented and increased the level of iodine intake from mild-moderate iodine deficiency to low adequacy. The level of thyroglobulin and thyroid volume decreased following IF, and there was an indication of fewer thyroid nodules. The incidence of hyperthyroidism increased transiently following IF but subsequently decreased below the pre-fortification level. Conversely, thyroid-stimulating hormone levels and the prevalence of thyroid autoimmunity increased along with an increase in the incidence of hypothyroidism. These trends were mirrored in the trends in treatments for thyroid disease. Most differences in thyroid health and disease between regions with different iodine intake levels before IF attenuated. This review illustrates the importance of a monitoring program to detect both beneficial and adverse effects and exemplifies how a monitoring program can be conducted when a nationwide health promotion program - as IF - is initiated.

Original languageEnglish
Article numbere230230
JournalEuropean Thyroid Journal
Volume13
Issue number3
Number of pages14
ISSN2235-0640
DOIs
Publication statusPublished - Jun 2024

Keywords

  • Denmark/epidemiology
  • Food, Fortified
  • History, 20th Century
  • History, 21st Century
  • Humans
  • Hyperthyroidism/epidemiology
  • Hypothyroidism/epidemiology
  • Incidence
  • Iodine/administration & dosage
  • Prevalence
  • Thyroglobulin/immunology
  • Thyroid Diseases/epidemiology
  • Thyroid Gland/pathology
  • Thyrotropin/blood
  • thyroid disease
  • epidemiology
  • iodine
  • public health

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