Objective: Oxygen free radicals (OFR) play a role in the pathogenesis of tissue damage in many pathological conditions via the peroxidation of membrane phospholipids. Experimental studies showed an elevated oxidative stress during hyperthyroidism, which is reduced by treatment. Therapy per se might decrease oxidative stress.
Design: Fasting plasma levels of thiobarbituric acid reacting substances (TBARS), vitamin E and coenzyme Q10 were measured in 22 hyperthyroid patients, before treatment for their thyroid disease, after 13.9 [SD 9.2] weeks, when they achieved an euthyroid state on thyrostatic drugs, and again after 47.7 [21.0] weeks, off therapy. No patient presented additional risk factors for increased lipoperoxidation and/or increased OFR levels. Smokers were asked to abstain from smoking overnight.
Methods: All analytes were measured by HPLC.
Results: In hyperthyroidism, plasma levels of TBARS were increased, whereas vitamin E and coenzyme Q10 were reduced. Average levels of TBARS and antioxidant agents returned to normal in euthyroid patients, without differences in relation to stop of thyrostatic therapy.
Conclusions: Our data confirm the presence of oxidative stress and decreased anti-oxidant metabolites in hyperthyroid patients, which are corrected in euthyroidism, without any influence of thyrostatic drugs per se. Nutritional support with antioxidant agents, which are defective during hyperthyroidism, is warranted.