title: Thyroid function and cardiovascular disease risk factors in euthyroid adults: a cross-sectional and longitudinal study.
abstract: OBJECTIVE
  We explored the cross-sectional and longitudinal associations of thyroid function within the normal range with cardiovascular disease (CVD) risk factors and adiposity measures.
  
  
  METHODS
  A total of 3483 (50·4% women) participants for the cross-sectional CVD study and 1630 (41·2% women) participants for the cross-sectional body composition substudy were drawn from the Framingham Third Generation Exam 1; 2912 participants (50·1% women) for the longitudinal CVD study and 713 participants (35·9% women) for the longitudinal body composition substudy were drawn from the Framingham Third Generation Exams 1-2. Thyroid function was assessed by thyrotropin [thyroid-stimulating hormone (TSH)] and free thyroxine (fT4) concentrations within the reference range at Exam 1. The associations between thyroid function and CVD risk factors were modelled via multivariable-adjusted regression models. Multivariable adjustment included age, sex, current smoking, postmenopausal status and BMI.
  
  
  RESULTS
  Cross-sectionally, higher TSH concentration was associated with increased odds of hypertriglyceridaemia [odds ratio (OR)=1·10], and higher BMI (β = 0·19 kg/m2), total cholesterol (β = 0·05 mmol/l), triglycerides (β = 0·0006 mmol/l) and subcutaneous adipose tissue (SAT) volume (β = 38·8 cm3) (all P < 0·05). Cross-sectionally, fT4 was inversely associated with metabolic and adiposity-related CVD risk factors, including obesity (OR = 1·17), hypertriglyceridaemia (OR = 1·09), BMI (β = 0·42 kg/m2), total cholesterol (β = 0·05 mmol/l), triglycerides (β = 0·0002 mmol/l), visceral adipose tissue (VAT) volume (β = -20·7 cm3) and attenuation (0·17 HU) and VAT/SAT ratio (β = -0·01) (all P < 0·05). However, during 6·1 years of follow-up, baseline TSH and fT4 levels were not longitudinally associated with CVD risk factors and adiposity measures.
  
  
  CONCLUSIONS
  Thyroid function within the normal range is cross-sectionally, but not longitudinally, associated with CVD risk factors and adiposity measures.
authors.affiliation: National Heart, Lung and Blood Institute's Division of Intramural Research, The Framingham Heart Study, Population Studies Branch, Framingham, Boston, MA, USA.
authors.forename: Jane J
authors.initials: JJ
authors.lastname: Lee
authors.affiliation: National Heart, Lung and Blood Institute's Division of Intramural Research, The Framingham Heart Study, Population Studies Branch, Framingham, Boston, MA, USA.
authors.forename: Alison
authors.initials: A
authors.lastname: Pedley
authors.affiliation: Division of Endocrinology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Ellen
authors.initials: E
authors.lastname: Marqusee
authors.affiliation: National Heart, Lung and Blood Institute's Division of Intramural Research, The Framingham Heart Study, Population Studies Branch, Framingham, Boston, MA, USA.
authors.forename: Patrice
authors.initials: P
authors.lastname: Sutherland
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
authors.affiliation: Department of Biostatistics, Boston University, Boston, MA, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Massaro
authors.affiliation: National Heart, Lung and Blood Institute's Division of Intramural Research, The Framingham Heart Study, Population Studies Branch, Framingham, Boston, MA, USA.|Division of Endocrinology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Caroline S
authors.initials: CS
authors.lastname: Fox
mesh_terms: D050154:Adiposity; D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000209:etiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000032:analysis; D013974:Thyroxine / Q000032:analysis; D055815:Young Adult
chemical_list: D013972:Thyrotropin; D013974:Thyroxine