Case control study of antioxidant markers in autoimmune thyroid disorders

Abstract

Background and objectives: There is often an imbalance between reactive oxygen species production and antioxidant defence mechanisms in autoimmune thyroid disorders (AITD). The objective of the study was to evaluate the glutathione peroxidase (GPX), total antioxidant capacity (TAC) and malondialdehyde (MDA) levels and autoantibody levels in autoimmune thyroid disorders (AITD).
Methodology: In a case control study among patients with autoimmune thyroid disorders and normal control subjects, oxidative stress markers namely GPX, MDA levels, TAC was evaluated. Patients with lab confirmed thyroid functional abnormalities, both hypothyroid and hyperthyroid subjects, meeting inclusion criteria are selected as cases. Sample size was 67 for cases and controls. A pre designed and pretested questionnaire including nutritional history and family history is distributed among cases and controls to collect the demographic details. Morning blood samples were used for estimating T4, T3, TSH, TAC, GPX, MDA levels.
Results: Study population comprised of 38 hypothyroid and 29 hyperthyroid subjects with 67 euthyroid controls. Mean GPX values in hypothyroidism and hyperthyroidism subjects was statistically significantly lower than control group (0.21 ± 0.06 and 0.19 ± 0.06 vs 0.41 ± 0.12 nmol/mL). Mean MDA values in hypothyroidism and hyperthyroidism subjects was statistically significantly higher than control group (7.4 ± 1.5 and 7.6 ± 1.53 vs 4.7 ± 0.8 nmol/mL). Mean TAC values in hypothyroidism and hyperthyroidism subjects was statistically significantly lower than control group (554.7 ± 104.3 and 551.8 ± 69 vs 1166.1 ± 105.7 µmol TE/L).
Conclusion: Lower antioxidant markers (GPX and TAC) and higher oxidative stress marker (MDA) was observed among AITD subjects in comparison to age and sex matched controls. A statistically significant association between AITD and low GPX/TAC status was noted.