title: The effect of hypothyroidism, hyperthyroidism, and their treatment on parameters of oxidative stress and antioxidant status.
abstract: BACKGROUND
  Free radical-mediated oxidative stress has been implicated in the etiopathogenesis of several autoimmune disorders. Also, there is growing evidence supporting the role of reactive oxygen species in the pathogenesis of thyroid disorders. The aim of this study was to investigate the influence of hypothyroidism, hyperthyroidism, and their treatments on the metabolic state of oxidative stress, and antioxidant status markers.
  
  
  METHODS
  A total of 20 newly diagnosed patients with overt hypothyroidism due to Hashimoto's thyroiditis, 20 patients with overt hyperthyroidism due to Graves' disease, and 20 healthy subjects as the control group were enrolled in the study. Fasting blood samples (12 h), taken at the initiation, after the 30th and 60th day of therapy were analyzed for malondialdehyde, nitrite, vitamin E, vitamin A, beta-carotene, ascorbate, and myeloperoxidase and superoxide dismutase activity. No patient presented additional risk factors for increased reactive oxygen species levels.
  
  
  RESULTS
  Malondialdehyde, nitrite, vitamin E, and myeloperoxidase activity increased in patients with hypothyroidism. After 2 months, the levels of nitrite and vitamin E were reduced to control levels by treatment. The patients with hyperthyroidism had increased levels of malondialdehyde and myeloperoxidase activity in comparison with the controls. Treatment with propylthiouracil attenuated these increments after 1 month.
  
  
  CONCLUSIONS
  Our results reveal an increased generation of reactive oxygen species and impairment of the antioxidant system in patients with hyperthyroidism, and particularly in patients with hypothyroidism. These findings indicate that thyroid hormones have a strong impact on oxidative stress and the antioxidant system.
authors.affiliation: Department of Medical Biochemistry, Tunceli Government Hospital, Tunceli, Turkey. mdherdamar@yahoo.com
authors.forename: Hüsamettin
authors.initials: H
authors.lastname: Erdamar
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Demirci
authors.forename: Halil
authors.initials: H
authors.lastname: Yaman
authors.forename: M Kemal
authors.initials: MK
authors.lastname: Erbil
authors.forename: Tolga
authors.initials: T
authors.lastname: Yakar
authors.forename: Banu
authors.initials: B
authors.lastname: Sancak
authors.forename: Sehri
authors.initials: S
authors.lastname: Elbeg
authors.forename: Gürsel
authors.initials: G
authors.lastname: Biberoğlu
authors.forename: Ilhan
authors.initials: I
authors.lastname: Yetkin
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism*; D013956:Antithyroid Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000188:drug therapy / Q000378:metabolism*; D007037:Hypothyroidism / Q000188:drug therapy / Q000378:metabolism*; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D008875:Middle Aged; D009573:Nitrites / Q000097:blood; D018384:Oxidative Stress; D009195:Peroxidase / Q000097:blood; D011441:Propylthiouracil / Q000627:therapeutic use; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use*; D014801:Vitamin A / Q000097:blood; D014810:Vitamin E / Q000097:blood; D019207:beta Carotene / Q000097:blood
chemical_list: D000975:Antioxidants; D013956:Antithyroid Agents; D009573:Nitrites; D017382:Reactive Oxygen Species; D019207:beta Carotene; D014801:Vitamin A; D014810:Vitamin E; D008315:Malondialdehyde; D011441:Propylthiouracil; D009195:Peroxidase; D013482:Superoxide Dismutase; D013974:Thyroxine