title: Maternal thyroid function in different conditions of iodine nutrition in pregnant women exposed to mild-moderate iodine deficiency: an observational study.
abstract: OBJECTIVE
  We examined the effect of different conditions of nutritional iodine intake on maternal thyroid function throughout gestation in a cohort of healthy, anti-thyroid antibody-negative women from a mild-moderately iodine-deficient (ID) area.
  
  
  METHODS
  Observational cohort study.
  
  
  METHODS
  The study included 168 women receiving prenatal preparations containing 150 μg of iodine from early pregnancy (150-I group); 105 women who had regularly used (>2 years) iodized salt prior to becoming pregnant (I-salt group); 160 women neither taking iodine supplements nor using iodized salt (no-I group).
  
  
  METHODS
  Maternal TSH, FT3 and FT4 were determined throughout gestation.
  
  
  RESULTS
  Mean TSH concentrations were higher among the 150-I women than in the remaining two groups, and in a high proportion of them, TSH values were found to exceed the upper limit for gestational age. Conversely, the prevalence of low free-thyroxine levels in the 150-I women was similar to that observed in the I-salt women and markedly lower than that recorded for the no-I group.
  
  
  CONCLUSIONS
  The regular use of iodine-containing supplements proved effective in reducing the risk of inappropriately low FT4 levels during pregnancy. The observed TSH increase in 150-I women may be because of a transient stunning effect on the thyroid gland, occurring as a result of the abrupt increase in daily iodine intake. Whilst the importance of gestational iodine supplementation is undisputed, we believe that in mild-moderately ID areas, women considering conception should be advised to take iodine supplementation for several months prior to pregnancy.
authors.affiliation: Dipartimento Clinico-Sperimentale di Medicina e Farmacologia-Sezione di Endocrinologia, University of Messina, Messina, Italy.
authors.forename: Mariacarla
authors.initials: M
authors.lastname: Moleti
authors.forename: Beatrice
authors.initials: B
authors.lastname: Di Bella
authors.forename: Grazia
authors.initials: G
authors.lastname: Giorgianni
authors.forename: Alfredo
authors.initials: A
authors.lastname: Mancuso
authors.forename: Antonio
authors.initials: A
authors.lastname: De Vivo
authors.forename: Angela
authors.initials: A
authors.lastname: Alibrandi
authors.forename: Francesco
authors.initials: F
authors.lastname: Trimarchi
authors.forename: Francesco
authors.initials: F
authors.lastname: Vermiglio
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage* / Q000172:deficiency*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000517:prevention & control* / Q000652:urine; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood / Q000652:urine; D013974:Thyroxine / Q000097:blood / Q000652:urine; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood / Q000652:urine; D055815:Young Adult
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D007455:Iodine; D013974:Thyroxine