Serum Selenium Status in Autoimmune Thyroid Disorders: A Case-control Study

Introduction: Selenium is a trace element essential for normal health, playing a crucial role in thyroid hormone synthesis and metabolism. In Autoimmune Thyroid Disorders (AITD), selenium deficiency can exacerbate inflammation, impair thyroid hormone production and escalate tissue damage. Assessing the selenium status as part of comprehensive management strategies for AITD is crucial. Aim: To evaluate the selenium levels and autoantibody levels in AITD and to establish the risk of AITD among patients with low selenium. Materials and Methods: This case-control study was conducted at the Department of Surgery, Medicine, Biochemistry and Physiology, MOSC Medical College, Kolenchery, Kerala, India from July 2022 to May 2023. A total of 134 participants were enrolled, including 67 cases with AITD and 67 matched controls. Serum selenium levels, thyroid function {Triiodothyronine (T3), Thyroxine (T4),Thyroid Stimulating Hormone (TSH)} and thyroid autoantibodies {anti-Thyroid Peroxide (TPO) and antiThyroglobulin (TGO)} were evaluated using blood samples collected in the morning (6-8 AM). Statistical analysis was performed with Pearson’s correlation coefficient to assess relationships and Chi-square tests evaluated the association between selenium status and AITD. Odds Ratios (OR) for AITD in relation to selenium levels were calculated. Results: Study population comprised of 38 hypothyroid and 29 hyperthyroid subjects, along with 67 euthyroid controls. Mean selenium levels among AITDs cases (0.088±0.07 μg/ mL) were statistically significantly lower in comparison to controls (0.12±0.01 μg/mL). OR for association between serum selenium and AITD was 8.6 (95% CI 0.619-3.677; p<0.0001). Observed Relative Risk (RR) for low selenium to have AITD was 1.95. The Chi-square value of 8.59 with p=0.0034 indicated a statistically significant association between AITD and low selenium status. Conclusion: Selenium levels among hypothyroid and hyperthyroid subjects were significantly lower comparison to age- and sex-matched euthyroid controls. The calculated OR of 8.60 and an RR of 1.95 highlight selenium's potential role in thyroid health, particularly in regulating immune response and hormone metabolism.