title: Impact of nutritional iodine optimization on rates of thyroid hypoechogenicity and autoimmune thyroiditis: a cross-sectional, comparative study.
abstract: BACKGROUND
  Since several countries have established mandatory food iodine fortification, there has been a decrease in rates of iodine deficiency disorders in parallel with an increase in prevalence of autoimmune thyroid diseases. This study compared the nutritional iodine status and the prevalence of autoimmune thyroiditis and thyroid hypoechogenicity on ultrasound in schoolchildren in São Paulo (Brazil) in two distinct periods of time in which fortified salt had different concentrations of iodine.
  
  
  METHODS
  We conducted a cross-sectional study evaluating 206 children aged 7-14 years and without a history of thyroid disease. Assessments included measurements of thyrotropin (TSH), free thyroxine, antithyroperoxidase (anti-TPO), and antithyroglobulin (anti-TG) antibodies, urinary iodine concentration, and thyroid ultrasound.
  
  
  RESULTS
  Mean urinary iodine concentration was 165.1 μg/L. Eleven children (5.3%) were diagnosed with autoimmune thyroiditis based on at least two of four criteria adopted in our study: positive anti-TPO or anti-TG antibody, hypoechogenicity of the thyroid parenchyma on ultrasound, and a TSH >4.0 μU/mL. Comparing our results with those from a similar study conducted during a period in which concentrations of iodine in the salt were higher (median urinary iodine concentration >300 μg/L), we observed a trend toward a lower prevalence of autoimmune thyroiditis, although no definitive conclusion could be established.
  
  
  CONCLUSIONS
  The current nutritional iodine status in our cohort was within optimal levels and lower than levels found in 2003. The prevalence of autoimmune thyroiditis seems to be decreasing in parallel with a decrease in iodine intake, although we could not reach a definitive conclusion.
authors.affiliation: 1 Faculdade de Ciência Médicas da Santa Casa de São Paulo , São Paulo, Brazil .
authors.forename: Daniela M C
authors.initials: DM
authors.lastname: Miranda
authors.forename: Juliana N
authors.initials: JN
authors.lastname: Massom
authors.forename: Regina M
authors.initials: RM
authors.lastname: Catarino
authors.forename: Raimunda T M
authors.initials: RT
authors.lastname: Santos
authors.forename: Sônia S
authors.initials: SS
authors.lastname: Toyoda
authors.forename: Marília M S
authors.initials: MM
authors.lastname: Marone
authors.forename: Eduardo K
authors.initials: EK
authors.lastname: Tomimori
authors.forename: Osmar
authors.initials: O
authors.lastname: Monte
mesh_terms: D000293:Adolescent; D001323:Autoantibodies / Q000097:blood; D001938:Brazil / Q000453:epidemiology; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005527:Food, Fortified; D006801:Humans; D007455:Iodine; D008297:Male; D009752:Nutritional Status; D015995:Prevalence; D013954:Thyroglobulin / Q000276:immunology; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D013967:Thyroiditis, Autoimmune / Q000097:blood / Q000000981:diagnostic imaging / Q000453:epidemiology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014463:Ultrasonography
chemical_list: D001323:Autoantibodies; C006606:anti-thyroglobulin; D013972:Thyrotropin; D013954:Thyroglobulin; D007455:Iodine; D013974:Thyroxine