title: Subclinical thyroid dysfunction and cardiac function amongst minority ethnic groups in the UK: a cross sectional study.
abstract: BACKGROUND
  Subclinical thyroid disease is associated with abnormal cardiovascular haemodynamics and increased risk of heart failure. The burden of raised/low thyroid stimulating hormone (TSH) levels amongst South Asian (SA) and African-Caribbean (AC) minority groups in the UK is not well defined. Given that these groups are particularly susceptible to CVD, we hypothesised that STD would reflect abnormal cardiac function and heightened cardiovascular risk in these ethnic groups.
  
  
  METHODS
  We examined SA (n=1111, 56% male, mean age 57.6 yrs) and AC (n=763, 44% male, mean age 59.2 yrs) participants from a large heart failure screening study. Euthyroidism is defined as TSH (0.4 - 4.9 mlU/l), subclinical hypothyroidism is defined as a raised TSH with normal serum free thyroxine (FT4) concentrations (9-19 pmol/l). Subclinical hyperthyroidism is defined as a low TSH with both FT4 and free triiodothyronine (FT3) concentrations within range (2.6-5.7 pmol/l).
  
  
  RESULTS
  Across ethnic groups, prevalence of subclinical hypothyroidism was 2.9% (95% CI 2.1-3.7), and of hyperthyroidism was 2.0% (1.4-2.7). Hyperthyroidism was more common amongst SA compared to AC (2.8% vs. 0.9%, P=0.017), while rates of subclinical hypothyroidism were similar. On multivariate analysis of variations in subclinical thyroid function, ethnicity was not independently significant.
  
  
  CONCLUSIONS
  The prevalence of subclinical thyroid disorders amongst SA and AC minority groups in Britain reflects levels reported in other populations. The clinical cardiovascular significance of subclinical thyroid disease is unclear, and it does not appear to be ethnically specific.
authors.affiliation: Primary Care Clinical Sciences, University of Birmingham, UK. Electronic address: p.s.gill@bham.ac.uk.
authors.forename: Paramjit S
authors.initials: PS
authors.lastname: Gill
authors.forename: Jeetesh V
authors.initials: JV
authors.lastname: Patel
authors.forename: Julia
authors.initials: J
authors.lastname: Chackathayil
authors.forename: Craig
authors.initials: C
authors.lastname: Webster
authors.forename: Russell C
authors.initials: RC
authors.lastname: Davis
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Hughes
authors.forename: Gregory Y H
authors.initials: GY
authors.lastname: Lip
mesh_terms: D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data*; D044383:Black People / Q000706:statistics & numerical data*; D003430:Cross-Sectional Studies; D005260:Female; D006333:Heart Failure / Q000208:ethnology*; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood / Q000208:ethnology*; D007037:Hypothyroidism / Q000097:blood / Q000208:ethnology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000031:analogs & derivatives / Q000097:blood; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D014284:Triiodothyronine; C040407:3,3',5-triiodothyronamine; D013972:Thyrotropin; D013974:Thyroxine
keywords: Cardiovascular; Ethnicity; Thyroid