title: The role of free triiodothyronine in pathogenesis of infertility in levothyroxine-treated women with thyroid autoimmunity - a preliminary observational study.
abstract: BACKGROUND
  The aim of this study was to analyze the possible role of free triiodothyronine (FT3) in infertility and in levothyroxine-treated (LT4) euthyroid women with Hashimoto thyroiditis (HT).
  
  
  METHODS
  It is an observational retrospective case control study. Twenty one euthyroid women with HT on LT4 replacement therapy and a medical history of idiopathic infertility were included into the study. To achieve higher FT3 level, the dose of LT4 was increased in every patient. Fifteen fertile women with HT on LT4 replacement therapy served as a control group.
  
  
  RESULTS
  At baseline in the study group mean thyroid stimulating hormone (TSH) level was 1.96 μU/ml ± 0.84 μU/ml and mean FT3 was 4.07 pmol/l ± 0.78 pmol/l. The mean TSH level after the increase of LT4 was 0.60 μU/ml ± 0.45 μU/ml (p < 0.0001), and the mean FT3 was 5.12 pmol/l ± 0.77 pmol/l (p = 0.0001). Baseline TSH in the study group was higher than in controls (p < 0.0001) and baseline FT3 in the study group was lower than in controls (p = 0.0003).
  
  
  CONCLUSIONS
  Relatively low levels of FT3 in women with HT on LT4 replacement therapy may contribute to higher infertility rates.
authors.affiliation: Department of Endocrinology, Metabolism and Internal Medicine, Poznan University of Medical Sciences , Poznan , Poland and.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Sowiński
authors.forename: Nadia
authors.initials: N
authors.lastname: Sawicka-Gutaj
authors.forename: Paweł
authors.initials: P
authors.lastname: Gutaj
authors.forename: Marek
authors.initials: M
authors.lastname: Ruchała
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D050031:Hashimoto Disease / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D006801:Humans; D007247:Infertility, Female / Q000097:blood* / Q000209:etiology*; D010865:Pilot Projects; D012189:Retrospective Studies; D013974:Thyroxine / Q000627:therapeutic use*; D014284:Triiodothyronine / Q000097:blood / Q000502:physiology*
chemical_list: D014284:Triiodothyronine; D013974:Thyroxine
keywords: Female infertility; Hashimoto disease; hypothyroidism; thyroxine