title: Relationship between thyroid-stimulating hormone levels and risk of depression among the general population with normal free T4 levels.
abstract: OBJECTIVE
  This study assessed the relationship between thyroid-stimulating hormone (TSH) level and risk of depressive symptom in a population with no clinical or laboratory evidence of thyroid dysfunction.
  
  
  METHODS
  This retrospective cohort study included 13,017 subjects (7913 males and 5104 females), 17-84 years of age, who underwent health examinations at the hospital. Subjects had a Beck Depression Inventory (BDI) total score of ≤9 and fell within the normal range of free T4 levels at baseline. The association between gender-specific serum TSH tertile at baseline and the development of clinically significant depressive symptom (i.e., ≥19 BDI total score) on the follow-up visit was evaluated using the Cox proportional hazards model, with adjustment for demographic and life style factors.
  
  
  RESULTS
  The risk of depressive symptom was increased among subjects with the highest tertile TSH level (adjusted hazard ratio [HR], 2.236; 95% confidence interval [CI], 1.443-3.466; p<0.001) as compared with subjects with the lowest tertile in females, but not in males. Even among patients with normal TSH levels, females in the lowest-normal TSH tertile had a higher risk of depressive symptoms (adjusted HR, 2.279; 95% CI, 1.456-3.567; p<0.001) than did those in the highest tertile. The TSH level as a continuous variable significantly predicted the depressive symptoms in females (adjusted HR, 1.402; 95% CI, 1.002-1.812; p=0.027).
  
  
  CONCLUSIONS
  Our finding suggests that suboptimal thyroid function increases vulnerability to the occurrence of depressive symptom and represents a modifiable risk factor for depression in females.
authors.affiliation: Mental Health Clinic, National Cancer Center, Goyang, Republic of Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Kim
authors.affiliation: Department of Neuropsychiatry, Dongguk University Medical School, Dongguk University International Hospital, Goyang, Republic of Korea.
authors.forename: Se Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Mental Health Clinic, National Cancer Center, Goyang, Republic of Korea.
authors.forename: Sang Jin
authors.initials: SJ
authors.lastname: Rhee
authors.affiliation: Department of Statistics, Seoul National University, Seoul, Republic of Korea.
authors.forename: Iksoo
authors.initials: I
authors.lastname: Huh
authors.affiliation: Department of Psychiatry, Seoul National University Bundang Hospital, Seongnam, Republic of Korea; Institute of Human Behavioral Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Seoul National Hospital, Seoul, Republic of Korea.
authors.forename: Kyooseob
authors.initials: K
authors.lastname: Ha
authors.affiliation: Biomedical Research Institute, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
authors.forename: Jayoun
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Psychiatry and Institute of Clinical Psychopharmacology, Dongguk University College of Medicine, Goyang, Republic of Korea.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Chang
authors.affiliation: Department of Psychiatry, Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Republic of Korea.
authors.forename: Dae Hyun
authors.initials: DH
authors.lastname: Yoon
authors.affiliation: Department of Statistics, Seoul National University, Seoul, Republic of Korea. Electronic address: tspark@stats.snu.ac.kr.
authors.forename: Taesung
authors.initials: T
authors.lastname: Park
authors.affiliation: Mental Health Clinic, National Cancer Center, Goyang, Republic of Korea; Institute of Human Behavioral Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea. Electronic address: aym@snu.ac.kr.
authors.forename: Yong Min
authors.initials: YM
authors.lastname: Ahn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003866:Depressive Disorder / Q000097:blood* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D055815:Young Adult
chemical_list: D013972:Thyrotropin; D013974:Thyroxine
keywords: Depression; Subclinical thyroid function; Thyroid-stimulating hormone