Thyroid Hormones and Oxidative Stress

Abstract

Thyroid hormones have a pro-oxidant effect and cause increased lipid peroxidation. Lipid peroxidation is an extremely damaging process implicated in many diseases and could be a causative factor, responsible for the varied systemic manifestations of hyperthyroidism, like myopathy and myocardial insufficiency. The activities of antioxidant scavenging enzymes like erythrocyte superoxide dismutase, catalase, and glutathione peroxidase, which prevent lipid peroxidation, are also significantly affected by hyperthyroidism and hypothyroidism. Further, it has been observed in various studies that hypothyroidism does induce changes in free radical scavenging enzymes opposite to those observed in hyperthyroidism. Oxidative injury, therefore, is an important mechanism in the pathophysiology of hyperthyroidism.