title: Determination of oxidative stress in thyroid tissue and plasma of patients with Graves' disease.
abstract: BACKGROUND
  The aim of our study was to evaluate the oxidant/antioxidant status of thyroid tissue in Graves' disease (GD) patients and to compare the results of GD thyroid tissue with plasma of patients and healthy controls.
  
  
  METHODS
  We studied 25 consecutive patients with GD hyperthyroidism who underwent surgical treatment. The patients were divided into groups according to the duration of antithyroid drug treatment, the type of antithyroid drugs used, the presence of ophthalmopathy, and recurrence after a complete course of antithyroid drugs. Thiobarbituric acid-reacting substances (TBARS), glutathione peroxidase (GPx) activity, superoxide dismutase (SOD) activity, and total thiol (t-SH) content of tissue and plasma samples were determined.
  
  
  RESULTS
  TBARS concentrations were found to be significantly increased in GD patients' plasma compared with controls' plasma (0.1+/-0.02 nmol/mg protein vs. 0.062+/-0.01 nmol/mg protein). Significantly decreased t-SH concentrations were measured in GD patients' plasma compared with controls (8.26+/-1.9 nmol/mg protein vs. 13.03+/-3.3 nmol/mg protein). Tissue TBARS, t-SH, GPx, and SOD measurements in GD patients indicated significantly increased concentrations compared with the plasma levels of patients. Patients with shorter treatment duration before the operation had significantly increased plasma and tissue TBARS and decreased plasma and tissue t-SH concentrations. Patients on propylthiouracil treatment had significantly lower plasma and tissue concentrations of TBARS than patients on methimazole. Patients with recurrence had significantly higher plasma and tissue TBARS and lower plasma and tissue t-SH concentrations than patients treated for the first time.
  
  
  CONCLUSIONS
  In euthyroid GD patients on antithyroid drugs, increased oxidative stress and a compensatory increase in the antioxidant defense system are more prominent in thyroid tissue than in plasma. Patients who relapsed had markers indicating increased oxidative stress. Thus, ongoing autoimmunity may contribute to increased oxidative stress in GD patients, even in the euthyroid state.
authors.affiliation: Istanbul University, Istanbul Medical Faculty, Department of Biochemistry, Turkey.
authors.forename: Evin
authors.initials: E
authors.lastname: Ademoğlu
authors.forename: Neşe
authors.initials: N
authors.lastname: Ozbey
authors.forename: Yeşim
authors.initials: Y
authors.lastname: Erbil
authors.forename: Sevda
authors.initials: S
authors.lastname: Tanrikulu
authors.forename: Umut
authors.initials: U
authors.lastname: Barbaros
authors.forename: Burcu Tulumoğlu
authors.initials: BT
authors.lastname: Yanik
authors.forename: Alp
authors.initials: A
authors.lastname: Bozbora
authors.forename: Selçuk
authors.initials: S
authors.lastname: Ozarmağan