Low Selenium Lowers Thyroid Hormone

In this experiment, selenium deficiency had a major impact on the function of liver enzymes, in particular those that are involved in one-carbon metabolism reactions. Specifically, induced selenium deficiency reduced the activity of deiodinase enzymes in the liver that convert the precursor hormone T4 into the bioactive form of thyroid hormone T3, thus reducing serum thyroid hormone levels. In addition, enzymes that protect against lipid peroxidation (the selenoproteins glutathione reductase and thioredoxin reductase) were reduced in the presence of insufficient selenium.
(Journal of Nutritional Biochemistry, September 2014)

http://www.spectracell.com/volume-2014-issue-no-8-august/ Web. 03 September. 2014.