title: Thyroid nodules in an 11-year DanThyr follow-up study.
abstract: BACKGROUND
  Limited longitudinal data are available on changes in the thyroid gland structure in a population and how this is influenced by iodine fortification (IF).
  
  
  OBJECTIVE
  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).
  
  
  METHODS
  We conducted a longitudinal population-based study (DanThyr) where participants were examined before (1997) and after (2008) the Danish mandatory IF of salt (2000).
  
  
  METHODS
  We examined 2465 adults, and ultrasonography was performed by the same sonographers using the same equipment, after controlling performances.
  
  
  METHODS
  Change in thyroid gland structure was evaluated.
  
  
  RESULTS
  The follow-up period saw an increased prevalence of multinodularity (9.8%-13.8 %, P < .001), especially in the previously moderate ID region of Aalborg (9.1%-15.4%, P < .001), whereas no change in prevalence was seen for solitary nodules (5.6%-5.1%, P = .34). In individual participants, changes in thyroid structure and disappearance of thyroid nodules during the 11 years was common with an overall normalization rate of 21.2 (95% confidence interval [CI] = 17.9-24.9) per 1000 person-years. Solitary nodules had a significantly higher normalization rate than multiple nodules (normalization rate ratio 0.47 [95% CI = 0.32-0.67]). A regional difference (Aalborg vs Copenhagen) was seen between normalization rates of multiple nodules (normalization rate ratio 0.29 [95% CI = 0.12-0.64]), but not for solitary nodules (normalization rate ratio 0.81 [95% CI = 0.53-1.21]).
  
  
  CONCLUSIONS
  Changes in the thyroid gland structure with both appearance and disappearance of thyroid nodules are common after an iodization program.
authors.affiliation: Departments of Clinical Medicine and Endocrinology (A.K., I.B.P., P.L.), Aalborg University and Aalborg University Hospital, and Faculty of Medicine (T.J.), Aalborg University, DK-9000 Aalborg, Denmark; Research Centre for Prevention and Health (L.B., T.J.), The Capital Region of Denmark, DK-2600 Glostrup, Denmark; Department of Endocrinology (L.B., N.K., H.P.), Bispebjerg University Hospital, DK-2400 Copenhagen, Denmark; Faculty of Health Sciences (T.J.), DK-2200 Copenhagen, Denmark; Department of Gastroenterology (L.O.), Slagelse Hospital, DK-4200 Slagelse, Denmark; and Department of Nutrition (L.B.R.), National Food Institute, Technical University of Denmark, DK-2860 Søborg, Denmark.
authors.forename: Anne
authors.initials: A
authors.lastname: Krejbjerg
authors.forename: Lena
authors.initials: L
authors.lastname: Bjergved
authors.forename: Inge Bülow
authors.initials: IB
authors.lastname: Pedersen
authors.forename: Nils
authors.initials: N
authors.lastname: Knudsen
authors.forename: Torben
authors.initials: T
authors.lastname: Jørgensen
authors.forename: Hans
authors.initials: H
authors.lastname: Perrild
authors.forename: Lars
authors.initials: L
authors.lastname: Ovesen
authors.forename: Lone Banke
authors.initials: LB
authors.lastname: Rasmussen
authors.forename: Peter
authors.initials: P
authors.lastname: Laurberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005527:Food, Fortified; D006801:Humans; D015994:Incidence; D007455:Iodine; D007881:Legislation, Food; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D017673:Sodium Chloride, Dietary; D016606:Thyroid Nodule / Q000000981:diagnostic imaging / Q000453:epidemiology*; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D017673:Sodium Chloride, Dietary; D007455:Iodine