Clinical review for general practice

The review focuses on the discussion of the role of selenium in the thyroid hormone metabolism and its impact on the risk of thyroid disorders, among which the most common are autoimmune thyroiditis (Hashimoto's disease) and Graves' disease. Selenium, which is a component of selenoproteins, such as glutathione peroxidase and iodothyronine deiodinases, is involved in the thyroid hormone synthesis and regulation and has an antioxidant effect on thyrocytes. Selenium deficiency can contribute to the development of thyroid disorders, aggravating the inflammatory processes and increasing the levels of antibodies against thyroid peroxidase (TPO AB) and thyroglobulin (TG AB).
Clinical trials show that selenium supplements can reduce the levels of thyroid autoantibodies in patients with autoimmune thyroiditis, thereby improving the thyroid structure and reducing inflammation. In patients with Graves' disease, selenium supplements demonstrate a positive effect on the ophthalmopathy progression and quality of life. However, the effect of selenium varies depending on the mineral baseline levels, which emphasizes the need for individual approach to treatment. The literature review shows an important role of selenium in maintaining health of the thyroid gland and emphasizes the need for further research aimed to optimize therapy based on the selenium supplementation.
Keywords: thyroid hormones, thyrotoxicosis, autoimmune thyroiditis, selenium, antioxidants.

22. Xu B, Wu D, Ying H, Zhang Y. A pilot study on the beneficial effects of additional selenium supplementation to methimazole for treating patients with graves’ disease. Turkish J Med Sci 2019;49(3):715-22. DOI: 10.3906/sag-1808-67 23. Kahaly GJ, Riedl M, König J et al. Double-Blind, Placebo-Controlled, Randomized Trial of Selenium in Graves Hyperthyroidism. J Clin Endocrinol Metab 2017;102(11):4333-41. DOI: 10.1210/jc.2017-01736 24. Caturegli P, De Remigis A, Rose NR. Hashimoto thyroiditis: clinical and diagnostic criteria. Autoimmun Rev 2014;13(4-5):391-7. DOI: 10.1016/j.autrev.2014.01.007 25. Wang F, Li C, Li S et al. Selenium and thyroid diseases. Front Endocrinol (Lausanne) 2023;14:1133000. DOI: 10.3389/fendo.2023.1133000 26. Ragusa F, Fallahi P, Elia G et al. Hashimotos‘ thyroiditis: Epidemiology, pathogenesis, clinic and therapy. Best Pract Res Clin Endocrinol Metab 2019;33(6):101367. DOI: 10.1016/j.beem.2019.101367 27. Ferrari SM, Ragusa F, Elia G et al. Precision medicine in autoimmune thyroiditis and hypothyroidism. Front Pharmacol 2021;12:750380. DOI: 10.3389/fphar.2021.750380 28. Spallholz JE, Boylan LM, Larsen HS. Advances in understanding selenium’s role in the immune system. Ann New York Acad Sci 1990;587:123-39. DOI: 10.1111/j.1749-6632.1990.tb00140.x 29. Taylor EW. Selenium and cellular immunity. evidence that selenoproteins may be encoded in the +1 reading frame overlapping the human Cd4, Cd8, and hla-Dr genes. Biol Trace Element Res 1995;49(2-3):85- 95. DOI: 10.1007/bf02788958 30. Kryczyk-Kozioł J, Prochownik E, Błażewska-Gruszczyk A et al. Assessment of the effect of selenium supplementation on production of selected cytokines in women with hashimoto’s thyroiditis. Nutrients 2022;14(14):2869. DOI: 10.3390/nu14142869 31. Ferrari SM, Fallahi P, Di Bari F et al. Myo-inositol and selenium reduce the risk of developing overt hypothyroidism in patients with autoimmune thyroiditis. Eur Rev Med Pharmacol Sci 2017;21(2 Suppl):36-42. 32. Paparo SR, Ferrari SM, Patrizio A et al. Myoinositol in autoimmune thyroiditis. Front Endocrinol 2022;13:930756. DOI: 10.3389/fendo.2022.930756 33. Yu L, Zhou L, Xu E et al. Levothyroxine monotherapy versus levothyroxine and selenium combination therapy in chronic lymphocytic thyroiditis. J Endocrinol Invest 2017;40(11):1243-50. DOI: 10.1007/s40618- 017-0693-z 34. Qiu Y, Xing Z, Xiang Q et al. Insufficient evidence to support the clinical efficacy of selenium supplementation for patients with chronic autoimmune thyroiditis. Endocrine 2021;73(2):384-97. DOI: 10.1007/s12020-021-02642-z 35. Dumont E, Vanhaecke F, Cornelis R. Selenium speciation from food source to metabolites: A critical review. Anal Bioanal Chem 2006;385(7):1304-23. DOI: 10.1007/s00216-006-0529-8 36. Huang Y, Wang Q, Gao J et al. Daily dietary selenium intake in a high selenium area of enshi, China. Nutrients 2013;5(3):700-10. DOI: 10.3390/nu5030700 37. Hawkes WC, Richter BD, Alkan Z et al. Response of selenium status indicators to supplementation of healthy north American men with highselenium yeast. Biol Trace Element Res 2008;122(2):107-21. DOI: 10.1007/s12011-007-8066-7 38. Maria Del Bas J, Rodríguez B, Puiggròs F et al. Hepatic accumulation of s-adenosylmethionine in hamsters with non-alcoholic fatty liver disease associated with metabolic syndrome under selenium and vitamin e deficiency. Clin Sci (London) 2019;133(3):409-23. DOI: 10.1042/cs20171039 39. Yetgin S, Hincal F, Başaran N, Ciliv G. Serum selenium status in children with iron deficiency anemia. Acta Haematol 1992;88(4):185-8. DOI: 10.1159/000204683 40. Knezevic J, Starchl C, Tmava Berisha A, Amrein K. Thyroid-Gut-Axis: How does the microbiota influence thyroid function? Nutrients 2020;12(6):1769. DOI: 10.3390/nu12061769 41. Zhou J, Chen X. Tolerable upper intake level on vitamins and minerals. Wei sheng yan jiu = J Hyg Res 2004;33(6):771-3.