Oxidative stress and antioxidant enzyme activities in patients with Hashimoto's thyroiditis

We investigated the parameters of oxidative stress in 71 Hashimoto's thyroiditis patients. They were divided into three sub-groups according to the thyroid function: group I'euthyroid subjects; group II'hypothyroid subjects; and group III'subjects treated with Levothyroxin. Thirty healthy subjects were studied as controls. The level of lipid peroxidation (malondialdehyde, MDA) in the plasma and the antioxidant defences such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities in erythrocytes were measured. Concentrations of MDA and SOD activity were not different in sub-groups of patients and controls. CAT activity was significantly lower in group II in comparison with both controls (p=0.01) and group III (p=0.02) as well as in group I compared to the controls (p=0.04). Activity of GPX in erythrocytes in hypothyroidism was significantly higher compared to controls (p=0.02). GPX activity in both groups I and III tended to be lower in comparison with controls. Our results indicate a deficiency of cellular antioxidative defense in Hashimoto's thyroiditis patients in all stages of disease. Accordingly, we suppose that the supplementation with antioxidants from an early stage of the disease, in addition to thyroid hormone replacement, may have a positive benefit in the treatment. © Springer-Verlag London Limited 2007.