title: Association of triiodothyronine levels with future development of metabolic syndrome in euthyroid middle-aged subjects: a 6-year retrospective longitudinal study.
abstract: BACKGROUND
  Several cross-sectional studies have reported that thyroid hormone levels are associated with cardiovascular risk markers and metabolic syndrome (MetS) even in euthyroid subjects. However, the prognostic role of serum thyroid hormone levels in the risk of incident MetS has not been elucidated.
  
  
  OBJECTIVE
  We aimed to investigate the associations of baseline serum thyroid hormone levels with the development of MetS in healthy subjects.
  
  
  METHODS
  This 6-year, cross-sectional, longitudinal and follow-up study was conducted in 12 037 euthyroid middle-aged subjects without MetS subjected to comprehensive health examinations. Subjects were grouped according to total triiodothyronine (T3) quartiles. The hazard ratio (HR) for the development of MetS according to T3 quartiles was estimated using Cox proportional hazards model.
  
  
  RESULTS
  During the 6-year period, 3544 incident cases of MetS (29%) were identified. The proportion of subjects with incident MetS increased across the T3 quartiles (Pfor trend <0.001). The HR and 95% confidence interval (CI) for the development of MetS were significantly higher in the highest T3 quartile compared with the lowest T3 quartile even after adjusting for confounding variables including gender, age and smoking (HR: 1.238, 95% CI: 1.128-1.358,P< 0.001).
  
  
  CONCLUSIONS
  In euthyroid middle-aged subjects, serum T3 levels are associated with increased risk for future development of MetS.
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Internal Medicine, Soonchunhyang University Hospital, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Hye Jeong
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Medicine, Changwon Samsung Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea.
authors.forename: Ji Cheol
authors.initials: JC
authors.lastname: Bae
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Internal Medicine, Soonchunhyang University Hospital, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Hyeong Kyu
authors.initials: HK
authors.lastname: Park
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Internal Medicine, Soonchunhyang University Hospital, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Dong Won
authors.initials: DW
authors.lastname: Byun
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Internal Medicine, Soonchunhyang University Hospital, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Kyoil
authors.initials: K
authors.lastname: Suh
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Internal Medicine, Soonchunhyang University Hospital, Soonchunhyang University College of Medicine, Seoul, Korea.
authors.forename: Myung Hi
authors.initials: MH
authors.lastname: Yoo
authors.affiliation: Department of Health Promotion CenterSamsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jee
authors.initials: J
authors.lastname: Jae Hwan
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jae Hyeon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yong-Ki
authors.initials: YK
authors.lastname: Min
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Sun Wook
authors.initials: SW
authors.lastname: Kim
authors.affiliation: Division of Endocrinology and MetabolismDepartment of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000175:diagnosis*; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D014284:Triiodothyronine