title: Thyroid hormone levels predict the change in body weight: a prospective study.
abstract: BACKGROUND
  Different studies, mostly cross-sectional, have found an association between low levels of thyroid hormones, even within the normal range, and a greater body mass index. The aim of this study was to determine the association between thyroid function and the risk for obesity.
  
  
  METHODS
  In this population-based prospective study, measurements were made of anthropometric parameters, thyroid hormone function and urinary iodine in a cohort of the Pizarra Study (n = 937), and repeated 6 years later (n = 784). At the second point, measurements were also made of leptin and adiponectin.
  
  
  RESULTS
  Among the persons who were not obese at the start of the study, the odds ratio (OR) of becoming obese for those in the fourth quartile (Q(4)) for free triiodothyronine (FT3) (versus those in Q(1)) was 2·94 (1·46-5·90) (P = 0·005). The OR of becoming obese in persons in Q(4) of FT4 (versus those in Q(1)) was 3·06 (1·23-7·43) (P = 0·01). Those persons in Q(4) of weight gain had a higher FT3 at the 6-year follow-up than those whose weight gain was in Q(1) (P < 0·001). Leptin correlated with thyrotropin (β = 0·58, P = 0·001) and the FT4 (β = -1·12, P = 0·005). Adiponectin correlated with FT3 (r = -0·24, P < 0·001). The urinary iodine correlated negatively with both the BMI (β = -0·08, P = 0·01) and the increase in weight (β = -0·08, P = 0·04).
  
  
  CONCLUSIONS
  The changes in the thyroid hormones could be the consequence, rather than the cause, of the increase in weight. The same pathophysiological mechanisms that induce obesity might also be modifying the thyroid hormone pattern.
authors.affiliation: Servicio de Endocrinología y Nutrición, Hospital Regional Universitario Carlos Haya, Málaga, Spain.
authors.forename: Federico
authors.initials: F
authors.lastname: Soriguer
authors.forename: Sergio
authors.initials: S
authors.lastname: Valdes
authors.forename: Sonsoles
authors.initials: S
authors.lastname: Morcillo
authors.forename: Isabel
authors.initials: I
authors.lastname: Esteva
authors.forename: Maria C
authors.initials: MC
authors.lastname: Almaraz
authors.forename: Maria S R
authors.initials: MS
authors.lastname: de Adana
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Tapia
authors.forename: Marta
authors.initials: M
authors.lastname: Dominguez
authors.forename: Carolina
authors.initials: C
authors.lastname: Gutierrez-Repiso
authors.forename: Elehazara
authors.initials: E
authors.lastname: Rubio-Martin
authors.forename: Lourdes
authors.initials: L
authors.lastname: Garrido-Sanchez
authors.forename: Vidal
authors.initials: V
authors.lastname: Perez
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Garriga
authors.forename: Gemma
authors.initials: G
authors.lastname: Rojo-Martinez
authors.forename: Eduardo
authors.initials: E
authors.lastname: Garcia-Fuentes
mesh_terms: D052242:Adiponectin / Q000097:blood*; D000328:Adult; D001835:Body Weight; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D007455:Iodine / Q000652:urine; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood; D011446:Prospective Studies; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D015430:Weight Gain / Q000502:physiology; D015431:Weight Loss / Q000502:physiology
chemical_list: D052242:Adiponectin; D020738:Leptin; D013963:Thyroid Hormones; D014284:Triiodothyronine; D013972:Thyrotropin; D007455:Iodine