title: The relation between changes in thyroid function and anthropometric indices during long-term follow-up of euthyroid subjects: the Tehran Thyroid Study (TTS).
abstract: OBJECTIVE
  Uncertainties exist regarding the causal relationship between thyroid function tests (TFT) within the euthyroid range and anthropometric measures. This longitudinal cohort is aimed to examine the relationship between the two conditions.
  
  
  METHODS
  Euthyroid participants of Tehran Thyroid Study (TTS) attending phase I (1999-2001) were included in this study and were followed up to phase IV (2008-2011). TSH and free T4 (fT4) levels as well as weight (Wt), waist circumference (WC), hip circumference (HC) and waist-to-hip ratio (WHR) were measured at both phases.
  
  
  RESULTS
  971 women and 784 men were included in the analysis. During 9.7years of follow-up, increases in TSH levels, Wt and WHR as well as a decrease in fT4 level were observed. Multivariable regression analysis showed a significant relationship between TSH changes and alterations in WC in women (β=0.69, P=0.021) and men (β=0.61, P=0.038). Moreover, a significant negative association of ΔfT4 with changes in weight was documented (β=-0.49, P=0.001 in women and β=-0.56, P<0.001 in men). Additionally, we found a negative relationship between ΔfT4 and ΔHC in men (β=-0.36, P=0.001).
  
  
  CONCLUSIONS
  In both genders, there was a positive relationship between changes in TSH and waist circumference and conversely a negative association of changes of fT4 levels with weight over time.
authors.affiliation: Obesity Research Center.
authors.forename: Behrang
authors.initials: B
authors.lastname: Motamed
authors.affiliation: Obesity Research Center.
authors.forename: Anita
authors.initials: A
authors.lastname: Eftekharzadeh
authors.affiliation: Obesity Research Center fhospanah@endocrine.ac.ir.
authors.forename: Farhad
authors.initials: F
authors.lastname: Hosseinpanah
authors.affiliation: Prevention of Metabolic Disorders.
authors.forename: Maryam
authors.initials: M
authors.lastname: Tohidi
authors.affiliation: Prevention of Metabolic Disorders.
authors.forename: Mitra
authors.initials: M
authors.lastname: Hasheminia
authors.affiliation: Endocrine Research CenterResearch Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Fereidoun
authors.initials: F
authors.lastname: Azizi
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007492:Iran; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood; D055105:Waist Circumference / Q000502:physiology*; D049629:Waist-Hip Ratio
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine