title: Evaluation of oxidative stress, the activities of paraoxonase and arylesterase in patients with subclinical hypothyroidism.
abstract: BACKGROUND
  In subclinical hypothyroidism (SH), serum lipid and lipoprotein concentrations are frequently changed. Compared with the healthy population, the levels of oxidized low-density lipoprotein cholesterol are higher, and the levels of high-density lipoprotein cholesterol are lower. In patients with SH, the mechanism of atherosclerosis may be attributed to the lipid abnormalities. There is evidence showing that oxidation plays an important role during the process of atherosclerosis. In this study, we evaluated the activity of paraoxonase (PON) and arylesterase (ARE) in patients with SH and investigated their relation with oxidative stress.
  
  
  METHODS
  The study enrolled 25 patients with SH and 20 sex- and age-matched healthy controls. The patient group and the control group were compared in terms of the activity of PON and ARE and the oxidative stress index.
  
  
  RESULTS
  Between 2 groups, no significant difference was found in terms of age, sex, serum levels of total cholesterol, low-density lipoprotein, and high-density lipoprotein. In the SH group, the activity of PON was significantly lower than that observed in the control group (P < 0.05). Arylesterase activity also was significantly lower in the group with SH, compared with the control group (P < 0.05). Oxidative stress index was found to be significantly higher in the patient group, compared with the healthy subjects (P < 0.01). Oxidative stress index showed a strong positive correlation with the levels of thyroid stimulating hormone in all cases (r = 0.60, P < 0.01).
  
  
  CONCLUSIONS
  The activity of PON and ARE were significantly decreased, and oxidative stress was increased in patients with SH. Lower activities of these 2 biomarkers indicate increased oxidative damage in SH. Atherosclerosis in SH can be attributed to increased oxidative stress.
authors: Haseki Education and Research Hospital, Nephrology, Istanbul, Turkey.
authors: Egemen
authors: E
authors: Cebeci
authors: Fatma
authors: F
authors: Alibaz-Oner
authors: Murat
authors: M
authors: Usta
authors: Selen
authors: S
authors: Yurdakul
authors: Mecdi
authors: M
authors: Erguney
mesh_terms: D000328:Adult; D043303:Aryldialkylphosphatase / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D016022:Case-Control Studies; D003710:Demography; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000201:enzymology* / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D018384:Oxidative Stress; D013960:Thyroid Function Tests
chemical_list: D002265:Carboxylic Ester Hydrolases; C019734:arylesterase; D043303:Aryldialkylphosphatase; C468406:PON1 protein, human