[The evaluation of selected oxidative stress parameters in patients after radioiodine treatment of hyperthyroidism].

UNLABELLED: Oxidative stress is an important factor of the hyperthyroidism pathogenesis. The radioiodine therapy is an approved treatment method of this common disease and it is connected with exposure to ionizing radiation, which induces increased generation of reactive oxygen species in patient's organism. The aim of the study was to estimate the selected oxidative stress parameters in hyperthyroid patients, initially treated with thiamazole and subsequently with radioiodine. The evaluated parameters were the activity of superoxide dismutase (CuZn-SOD), catalase (CAT) and glutathione peroxidase (GPx) in erythrocytes as well as the level of total antioxidative status (TAS) in plasma. MATERIAL AND METHODS: In the study participated 29 healthy volunteers and 27 hyperthyroid patients, treated with thiamazole and prepared for radioiodine therapy. The antioxidant enzymes activity and the level of TAS were measured before administration of radioiodine therapeutic dose (average 18.47 +/- 8.81 mCi) as well as 30 days after treatment and achieving euthyreosis. RESULTS: Hyperthyroid patients prepared with thiamazole for radioiodine therapy demonstrated higher GPx activity (p < 0.0001) and lower TAS level (p < 0.0001) than healthy people. Patients, who become euthyroid after 30 days from radioiodine therapy, were characterised by the increased activity of CAT (p < 0.05) and GPx (p < 0.05) as well as the higher level of TAS (p < 0.05). Patients after radioiodine treatment in comparison to the control group had the same activity of CAT and the level of TAS, although the activity of CuZn-SOD (p < 0.05) and GPx (p < 0.0001) occurred higher than in the control group. Moreover patients with hyperthyroidism before radioiodine treatment showed positive correlation between the level of TSH and TAS, whereas after radioiodine therapy they demonstrated positive correlation between the level of TSH and the activity of CuZn-SOD, CAT and GPx. However, there was no statistically significant correlation between the quantity of administrated radioiodine dose and the value of estimated oxidative stress parameters. CONCLUSIONS: The results of the study show the occurrence of oxidative stress in hyperthyroid patients prepared with thiamazole to radioiodine therapy. Euthyreosis achieved by radioiodine treatment effected on normalisation of the activity of CAT and the level of TAS, although the activity of CuZn-SOD and GPx stayed increased. After the analysis of correlation between TSH level, radioiodine dose and measured parameters we can conclude that the intensity of oxidative stress more depends on current thyreometabolic state than on the therapeutic method applied.