title: Association Between Thyroid Hormones, Lipids and Oxidative Stress Markers in Subclinical Hypothyroidism.
abstract: BACKGROUND
  Oxidative stress plays a role in the pathogenesis of many chronic diseases. It is recognized in overt hypothyroidism while its existence in subclinical hypothyroidism (SCH) is not well established. The aim of this study was to determine whether there was increased oxidation of lipids and proteins in SCH, and examine their association with lipids and thyroid hormones.
  
  
  METHODS
  Male adults (35-59 years) with SCH (n=467) and euthyroid controls (n=190) were studied. Anthropometric measurements, plasma lipids, thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total antioxidant capacity (T-AOC), lipid peroxidation products, malondialdehyde (MDA), advanced oxidation protein products (AOPP) and dityrosine concentrations were measured.
  
  
  RESULTS
  Plasma concentrations of MDA were significantly higher (p<0.05) in SCH (8.11±1.39 nmol/mL) compared with euthyroid controls (7.34±1.31 nmol/mL) while AOPP, dityrosine and T-AOC levels were not different. MDA was not associated with TSH (β=-0.019, P=0.759), FT4 (β=-0.062, P=0.323) and FT3 (β=-0.018, P=0.780) in SCH while levels increased with elevated total cholesterol (β=0.229, P=0.001), LDL (β=0.203, P=0.009) and triglycerides (β=0.159, P=0.036) after adjustment for age and body mass index. T-AOC reduced (β=-0.327, P=0.030) with increased MDA in euthyroid controls and not in SCH (β=-0.068, P=0.349), while levels increased with elevated triglycerides in both groups.
  
  
  CONCLUSIONS
  Oxidative stress was increased in subclinical hypothyroidism as evidenced by the elevated lipid peroxidation product, malondialdehyde, while protein oxidation was absent. Thus, reduction of oxidative stress may be beneficial in patients with subclinical hypothyroidism.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China; Molecular and Applied Nutrition Laboratory, School of Food Science and Technology, Jiangnan University, Wuxi, China; Department of Human Nutrition, Faculty of Health Science, Egerton University, Kenya.
authors.forename: Maureen Jepkorir
authors.initials: MJ
authors.lastname: Cheserek
authors.affiliation: Molecular and Applied Nutrition Laboratory, School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Gui-Rong
authors.initials: GR
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Arsene
authors.initials: A
authors.lastname: Ntazinda
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China; Molecular and Applied Nutrition Laboratory, School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Yong-Hui
authors.initials: YH
authors.lastname: Shi
authors.affiliation: Jiangnan University Hospital, Wuxi, Jiangsu, China.
authors.forename: Li-Ye
authors.initials: LY
authors.lastname: Shen
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China; Molecular and Applied Nutrition Laboratory, School of Food Science and Technology, Jiangnan University, Wuxi, China.
authors.forename: Guo-Wei
authors.initials: GW
authors.lastname: Le
keywords: hyperlipidemia; oxidative stress; subclinical hypothyroidism; thyroid hormones; thyroid stimulating hormone