Selenium Supplementation in Pregnant Women with Autoimmune Thyroiditis: A Practical Approach

Abstract

Selenium (Se) is an essential trace element with antioxidant and anti-inflammatory properties and a pivotal role in thyroid metabolism. Ensuring a sufficient Se supply is possible via a balanced, wholesome diet; however, Se content in foods may be different throughout geographical areas. Se supplementation is expected to improve inflammatory status in patients with autoimmune thyroiditis, especially in those with high activity, and has been demonstrated as effective in reducing the thyroid peroxidase antibodies titer. Se status seems to affect thyroid function in pregnancy, which prompts the potential role of Se supplementation in such patients. Few clinical trials have investigated the effectiveness of Se supplementation in pregnant women with thyroiditis, and their results suggest the safety and effectiveness of this element in reducing autoantibody levels and preventing postpartum thyroiditis development, although limited. Hence, more robust evidence is needed to confirm these data. The current study aims to summarize published data on the relationship between Se and thyroid status in pregnant women with thyroiditis and the potential use of Se. Moreover, an algorithm for Se supplementation is proposed for pregnant women with thyroiditis to help endocrinologists in daily clinical practice to consider Se status.

Keywords: autoimmune thyroiditis; pregnancy; selenium; thyroid.

Figure 1

Thyroid gland selenoproteins. Selenoprotein P (SELENOP) and glutathione peroxidase 3 (GPX3) are actively secreted from the thyrocyte and exert oxidoreductase functions, protecting thyrocytes from excessive H₂O₂ accumulation. Other selenoproteins, including Selenoprotein K, N, and S (SELENOK, SELENON, and SELENOS, respectively) take part in the quality control pathways within the endoplasmic reticulum. Type 1 (DIO1) and 2 iodothyronine deiodinase (DIO2) regulate thyroid hormone levels, converting T4 into T3. GPX4 and thioredoxin reductase 2 (TXNRD2) are localized in the mitochondria, affording protection against the hydrogen peroxide produced by the mitochondrial respiratory chain. This figure was created using Servier Medical Art templates, which is licensed under the Creative Commons Attribution 3.0 Unported License; https://smart.servier.com (accessed on 17 February 2022).

Figure 2

Proposed algorithm for selenium supplementation in pregnant women with thyroiditis. This figure was created using Servier Medical Art templates, which is licensed under the Creative Commons Attribution 3.0 Unported License; https://smart.servier.com (accessed on 17 February 2022).