title: Impact of hypothyroidism on the development of non-alcoholic fatty liver disease: A 4-year retrospective cohort study.
abstract: OBJECTIVE
  Hypothyroidism is reported to contribute to the development of nonalcoholic fatty liver disease (NAFLD). We compared the risk of the development of NAFLD among three groups with different thyroid hormonal statuses (control, subclinical hypothyroidism, and overt hypothyroidism) in a 4-year retrospective cohort of Korean subjects.
  
  
  METHODS
  Apparently healthy Korean subjects without NAFLD and aged 20-65 years were recruited (n=18,544) at health checkups performed in 2008. Annual health checkups were applied to the cohort for 4 consecutive years until December 2012. Based on their initial serum-free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels, they were classified into control, subclinical hypothyroidism (TSH >4.2 mIU/L, normal fT4), and overt hypothyroidism (TSH >4.2 mIU/L, fT4 <0.97 ng/dL) groups. NAFLD was diagnosed on the basis of ultrasonography findings.
  
  
  RESULTS
  NAFLD developed in 2,348 of the 18,544 subjects, representing an overall incidence of 12.7%: 12.8%, 11.0%, 12.7% in the control, subclinical hypothyroidism, and overt hypothyroidism groups, respectively. The incidence of NAFLD did not differ significantly with the baseline thyroid hormonal status, even after multivariate adjustment (subclinical hypothyroidism group: hazard ratio [HR]=0.965, 95% confidence interval [CI]=0.814-1.143, P=0.67; overt hypothyroidism group: HR=1.255, 95% CI=0.830-1.899, P=0.28).
  
  
  CONCLUSIONS
  Our results suggest that the subclinical and overt types of hypothyroidism are not related to an increased incidence of NAFLD.
authors.affiliation: Department of Gastroenterology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kil Woo
authors.initials: KW
authors.lastname: Lee
authors.affiliation: Department of Gastroenterology, Dankook University Hospital, Dankook University College of Medicine, Cheonan, Korea.
authors.forename: Ki Bae
authors.initials: KB
authors.lastname: Bang
authors.affiliation: Department of Endocrinology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Rhee
authors.affiliation: Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Heon Ju
authors.initials: HJ
authors.lastname: Kwon
authors.affiliation: Department of Biostatistics, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Mi Yeon
authors.initials: MY
authors.lastname: Lee
authors.affiliation: Department of Gastroenterology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Yong Kyun
authors.initials: YK
authors.lastname: Cho
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007037:Hypothyroidism / Q000150:complications* / Q000175:diagnosis*; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008099:Liver / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease / Q000150:complications* / Q000175:diagnosis* / Q000453:epidemiology; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013972:Thyrotropin / Q000032:analysis; D013974:Thyroxine / Q000032:analysis; D014463:Ultrasonography
chemical_list: D013972:Thyrotropin; D013974:Thyroxine
keywords: Hypothyroidism; Nonalcoholic fatty liver disease