Selenium deficiency mitigates hypothyroxinemia in iodine-deficient subjects

Abstract

Studies were performed to assess the role of combined selenium and iodine deficiency in the etiology of endemic myxedematous cretinism in a population in Zaire. One effect of selenium deficiency may be to lower glutathione peroxidase activity in the thyroid gland, thus allowing hydrogen peroxide produced during thyroid hormone synthesis to be cytotoxic. In selenium-and-iodine-deficient humans, selenium supplementation may aggravate hypothyroidism by stimulating thyroxin metabolism by the selenoenzyme type I iodothyronine 5'-deiodinase. Selenium supplementation is thus not indicated without iodine or thyroid hormone supplementation in cases of combined selenium and iodine deficiencies.

Nrf2 and selenoproteins are essential for maintaining oxidative homeostasis in erythrocytes and protecting against hemolytic anemia

“…29 Subsequent reports have shown that low serum selenium levels may also be associated with anemia in humans. [18][19][20] This study strongly supports the contention that selenium deficiency is a causative factor in anemia and can be explained by the loss of selenoprotein function, which is important for maintaining the oxidative status of erythrocytes. In the absence of selenoproteins, the Nrf2 gene battery inhibits ROS production and lysis, demonstrating the functional overlap of these antioxidant systems in preventing hemolytic anemia.…”

“…14 Selenium/selenoprotein deficiency has previously been shown to compromise the function of various immune cell types, [15][16][17] and low serum selenium has been suggested to contribute to anemia in humans. [18][19][20] Therefore, we were interested in evaluating the relative importance of selenoprotein activity for the homeostasis of hematopoietic lineages. In addition, our previous results showing overlapping but nonredundant function of selenoproteins and Nrf2 in cellular redox maintenance prompted us to consider the interaction of these 2 antioxidant systems.…”

Association of selenium with thyroid volume and echostructure in 35- to 60-year-old French adults

“…In combined iodine and selenium deficiency, selenium supplementation is not indicated without prior iodine supplementation (7,8). All these studies were conducted in severely selenium-and iodinedeficient populations.…”

Analysis of iodine and selenium trace elements in umbilical cord blood in cretinous regions in northwest China in 1999

“…Among the three counties, the level of selenium in Yijun was the lowest, in Lintong it was moderate, and in Ziyang it was the higher, which is in accordance with the results of previous investigations 6,7) . Increasing numbers of animal studies reveal that Se plays a role in sub-clinical cretinism as a factor of coordination, which aggravates the harm of iodine deficiency to brain tissue 8,9) . Firstly, as the active center of GSHPX, Se exerts a protective action similar to that of cellular membranes against the oxidation of lipid peroxide and hydrogen peroxide.…”

“…It is assumed that the cause is related to the following factors: First, among the three counties, the iodine level in Ziyang was the lowest while the level of selenium was clearly higher than those in the other two counties. It was reported that in conditions of insufficient iodine, high levels of selenium would aggravate mental retardation [16][17][18] . Second, in Ziyang County, intermarriage is more common, so there might be non-environmental factors to harm mental intelligence.…”