Selenium is an essential trace mineral. It is the active centre of many selenoproteins implicated in antioxidant defence mechanisms, thyroid metabolism and the immune function.
Several studies have demonstrated the benefits of selenium supplementation in the management of autoimmune thyroid disorders. In Hashimoto's disease, selenium supplementation appears to potentiate the activity of selenoproteins, thereby decreasing local inflammatory reactions, which decrease anti-TPO antibody production and improves thyroid morphology. In Graves' disease, administration of selenium could help to promote euthyroidism and appears to have a beneficial effect on the development of at least moderate or mild orbitopathy.
Several points, however, need clarification. Plasma or serum selenium concentrations do not reflect intrathyroid concentrations, and assay of selenium levels is therefore not recommended in routine practice. It is indispensible to identify a reliable marker of thyroidal selenium status or thyroidal oxidative stress to backup the value of selenium supplementation in the management of thyroidal disorders and so that treatment doses and durations may be better defined. Furthermore, treatment cost/benefit studies must also be performed on a larger scale.
Currently, progression of Hashimoto's disease cannot be avoided but levothyroxine treatment is perfectly tolerated and inexpensive. Selenium supplementation can only be considered as an option and justified if, at the lowest cost, it truly improves the quality of life of patients by the selenium itself stopping or slowing down thyroid destruction.
The same applies to postpartum thyroiditis. However, the expected benefits of selenium supplementation appear to be superior in indications such as Graves' disease or Graves' orbitopathy as current treatment options for these disorders are sometimes ineffective, insufficient or poorly tolerated.
The authors thank Merck Serono Laboratory (Lyon, France) for editorial assistance in the preparation of this article, as the paper has been checked by a native English speaker.
Clin Endocrinol. 2013;78(2):155-164. © 2013 Blackwell Publishing