Selenium and the thyroid: a close-knit connection.
BACKGROUND
The recent recognition that the essential trace element selenium is incorporated as selenocysteine in all three deiodinases has decisively confirmed the clear-cut link between selenium and thyroid function. It has additionally been established that the thyroid contains more selenium than any other tissue and that selenium deficiency aggravates the manifestation of endemic myxedematous cretinism and autoimmune thyroid disease.


METHODS
Clinical reports as well as a large number of biochemical articles linking selenium to thyroid have been considered. Interventional, prospective, randomized, controlled studies, including large observational studies, supplementing selenium in autoimmune thyroid disease, together with review articles published in Medline and Pubmed have undergone scrutiny. The methodological differences and variety of results emerging from these trials have been analyzed.


RESULTS
Evidence in support of selenium supplementation in thyroid autoimmune disease is evaluated, the results herein presented demonstrating the potential effectiveness of selenium in reducing the antithyroid peroxidase titer and improving the echostructure in the ultrasound examination. However, considerable discord remains as to who should comprise target groups for selenium treatment, who will most benefit from such treatment, the precise impact of the basal antithyroid peroxidase level, and the effect of disease duration on the treatment outcome. Clearly, further in-depth studies and evaluation are required concerning the mechanism of action of selenium as well as the choice of supplements or dietary intake.


CONCLUSIONS
Maintenance of "selenostasis" via optimal intake not only aids preservation of general health but also contributes substantially to the prevention of thyroid disease.
Duntas
Leonidas H
LH
Endocrine Unit, Evgenidion Hospital, University of Athens, 20 Papadiamantopoulou Street 115 28 Athens, Greece. ledunt@otenet.gr
D015551:Autoimmunity; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000378:metabolism; D011247:Pregnancy; D012643:Selenium / Q000378:metabolism* / Q000627:therapeutic use; D017279:Selenocysteine / Q000378:metabolism; D012645:Selenomethionine / Q000627:therapeutic use; D051140:Selenoproteins / Q000378:metabolism; D013961:Thyroid Gland / Q000276:immunology / Q000378:metabolism*; D013963:Thyroid Hormones / Q000096:biosynthesis; D013967:Thyroiditis, Autoimmune / Q000188:drug therapy; D014131:Trace Elements / Q000378:metabolism
D051140:Selenoproteins; D013963:Thyroid Hormones; D014131:Trace Elements; D017279:Selenocysteine; D012645:Selenomethionine; D007453:Iodide Peroxidase; D012643:Selenium