Limited longitudinal data are available on changes in the thyroid gland structure in a population and how this is influenced by iodine fortification (IF).
Our objective was to clarify how IF influenced thyroid gland structure in 2 regions with different iodine intake at baseline (Copenhagen, mild iodine deficiency [ID]; Aalborg, moderate ID).
We conducted a longitudinal population-based study (DanThyr) where participants were examined before (1997) and after (2008) the Danish mandatory IF of salt (2000).
We examined 2465 adults, and ultrasonography was performed by the same sonographers using the same equipment, after controlling performances.
Change in thyroid gland structure was evaluated.
The follow-up period saw an increased prevalence of multinodularity (9.8%-13.8 %, P