Erythrocytes response to oxidative challenge in relation to thyroid hormones

ABSTRACT

In order to analyze the possible relationship between metabolic rate and oxidative stress; we examined the susceptibility of erythrocytes in vitro oxidative challenge in hyperthyroid, hypothyroid and euthyroid patients in comparison to control subjects. The study included three groups of patients with either hyper, hypo- or euthyroidism. Each of these groups was compared with a control group [twenty-five apparently health subjects]. The hormonal parameters [T4, T3 and TSH] were measured by RIA technique. Erythrocytes thiobarbituric acid reactive substances were determined as basal values following their exposure to in vitro challenge with H20 2 as a marker for lipid peroxidation. H20 2 induced met-Hb was another parameter studied as an index for protein oxidation. Reduced glutathione was determined to be indicative for the antioxidant status in erythrocytes Hyperthyroid patients expressed significantly higher susceptibility to lipid peroxidation by producing greater thiobarbituric acid reactive substances concentrations before and after incubation with 5, 10 or 15 mM H20 2 [P>0.01]. H20 2 - induced met-Hb level was modified by different thyroid disorders as compared to control samples. Abnormal thyroid hormone levels were associated with significant reduction in the major intracellular antioxidant [glutathione]. Thyroid disorders were found to be associated with abnormal modifications in both oxidants production [reflected by increased lipid and protein oxidation] and antioxidants defenses [presented by glutathione]. Taken together these effects could explain the enhanced susceptibility in tissues of such disorders [presented here by erythrocytes] and later development of cardiovascular complications. Hence, we suggest the administration of antioxidants as adjuvant to the regular therapy, hopping to minimize the unavoidable thyroid complications