Oxidative stress in hypothyroid patients and the role of antioxidant supplementation

Context: The available data concerning oxidant stress and antioxidant capacity in hypothyroidism are scanty and inconclusive. While some authors suggest that tissues may be protected from oxidant damage because of a hypometabolic state in hypothyroidism, others report increased oxidative stress in hypothyroidism. Selenium acts as a cofactor for the thyroid hormone (TH) deiodinases that activate and then deactivate various THs and their metabolites. Selenium may inhibit thyroid autoimmunity. Aims: The study was designed, first, to study the impact of oxidative stress in patients of primary hypothyroidism due to autoimmune thyroiditis, by estimation of serum malondialdehyde (MDA) as a biomarker of oxidative stress. Second, to study the change in MDA level pre- and post-L-thyroxine treatment. Finally, to look into the possible role of selenium supplementation on oxidative stress in autoimmune hypothyroidism. Subjects and Methods: Patients attending endocrine outpatient department (OPD) services of IPGMER and SSKM hospital were considered for the study. Sixty treatment-naive adult patients (age > 18 years) with hypothyroidism were included in the study. The patients were divided into two groups, each comprised thirty patients. One group was treated with L-thyroxine and placebo (Group A). The other group received L-thyroxine replacement along with selenium (100 mcg twice a day) as antioxidant supplementation (Group B). The patients were blinded about selenium and placebo. The study duration for both groups was 6 months. The starting dose of L-thyroxine was 1.6 mcg/kg body weight free thyroxine (FT4), and thyroid-stimulating hormone (TSH) was repeated after 12 weeks. L-thyroxine dose adjustments were done if needed. MDA was assessed at the beginning and at the end of the study, i.e., after 6 months of treatment. The control cohort was composed of thirty healthy adults. Only overt hypothyroidism (OH) cases were included in the study. Statistical Analysis Used : Normality of data was determined using Anderson-Darling test, Shapiro-Wilk test, and QQ plot. P values were calculated using ANOVA and post hoc Bonferroni tests for normally distributed data. Correlation analysis was carried out using Pearson correlation test. P Results: After treatment in Group A patients, FT4 showed a significant increment while TSH value decreased. MDA level reduced after treatment, ( P P P Conclusions: Oxidative stress compounds hypothyroidism. Hypothyroidism is a state of increased oxidative stress. In this study, biomarker, MDA level is high in treatment-naive primary hypothyroid patients. After treatment with L-thyroxine, the stress marker is reduced to a significant extent. MDA can be used as a useful biomarker to measure and monitor oxidative stress. The role of the addition of antioxidant in the form of selenium remained inconclusive.