title: Non-alcoholic fatty liver disease across the spectrum of hypothyroidism.
abstract: OBJECTIVE
  The aim of this study was to characterize the relationship between the broad spectrum of hypothyroidism and NAFLD.
  
  
  METHODS
  A cross-sectional study with 4648 health check-up subjects (2324 cases with hypothyroidism vs. age- and sex-matched controls) was conducted. The subjects were categorized as having either subclinical [thyroid-stimulating hormone (TSH) ≥4.1 mIU/L and normal free thyroixine (T(4)) level (0.7-1.8 ng/dl)] or overt hypothyroidism [free T(4)<0.7 ng/dl]. NAFLD was diagnosed on the basis of typical ultrasonographic findings, and alcohol consumption of less than 20 g/day in the absence of other causes of liver disease.
  
  
  RESULTS
  The mean age of the subjects was 48.6±11.8 years and 62.4% were female. NAFLD was significantly associated with hypothyroidism (30.2% patients vs. 19.5% control, p<0.001). The prevalence of NAFLD and abnormal liver enzyme levels (ALT>33/25 IU/L) increased steadily with increasing grades of hypothyroidism (for NAFLD, subclinical: 29.9% and overt: 36.3%; for abnormal ALT, 20.1% and 25.9%, p<0.001, respectively). Multivariate regression analysis showed that NAFLD was statistically significantly associated with hypothyroidism (odds ratio (OR) 1.38, 95% confidence interval (CI), 1.17-1.62) and the grade of hypothyroidism in a dose-dependent manner (OR 1.36, 95% CI, 1.16-1.61 in subclinical hypothyroidism and OR 1.71, 95% CI, 1.10-2.66 in overt hypothyroidism).
  
  
  CONCLUSIONS
  Subclinical hypothyroidism, even in the range of upper normal TSH levels, was found to be related to NAFLD in a dose-dependent manner. Hypothyroidism is closely associated with NAFLD independently of known metabolic risk factors, confirming a relevant clinical relationship between these two diseases.
authors.affiliation: Department of Internal Medicine, Healthcare Research Institute, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, South Korea.
authors.forename: Goh Eun
authors.initials: GE
authors.lastname: Chung
authors.forename: Donghee
authors.initials: D
authors.lastname: Kim
authors.forename: Won
authors.initials: W
authors.lastname: Kim
authors.forename: Jeong Yoon
authors.initials: JY
authors.lastname: Yim
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Park
authors.forename: Yoon Jun
authors.initials: YJ
authors.lastname: Kim
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Yoon
authors.forename: Hyo-Suk
authors.initials: HS
authors.lastname: Lee
mesh_terms: D000328:Adult; D000410:Alanine Transaminase / Q000097:blood; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005234:Fatty Liver / Q000000981:diagnostic imaging / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology* / Q000378:metabolism; D008297:Male; D024821:Metabolic Syndrome / Q000453:epidemiology* / Q000378:metabolism; D008875:Middle Aged; D015999:Multivariate Analysis; D065626:Non-alcoholic Fatty Liver Disease; D015995:Prevalence; D012307:Risk Factors; D012720:Severity of Illness Index; D013974:Thyroxine / Q000097:blood; D014463:Ultrasonography
chemical_list: D000410:Alanine Transaminase; D013974:Thyroxine