Two systematic review s have evaluated controlled trials among patients with autoimmune thyroiditis and report that selenium supplementation decreases circulating thyroid autoantibodies .
The immunomodulatory effects of selenium might involve reducing proinflammatory cytokine release .
In Graves ’ disease , some , but not all , trials indicate that adjuvant selenium supplementation enhances the restoration of biochemical euthyroidism , and might benefit patients with mild Graves ’ orbitopathy .
The available evidence from trials does not support routine selenium supplementation in the st and ard treatment of patients with autoimmune thyroiditis or Graves ’ disease .
However , correction of moderate to severe selenium deficiency may offer benefits in preventing , as well as treating , these disorders .
Purpose of review This review provides an appraisal of recent evidence for or against selenium supplementation in patients with autoimmune thyroid diseases , and discusses possible effect mechanisms .
Recent findings Epidemiological data suggest an increased prevalence of autoimmune thyroid diseases under conditions of low dietary selenium intake .
However , clinical ly relevant effects of selenium supplementation , including improvement in quality of life , are more elusive .
Effects of a six month treatment with selenomethionine in patients with autoimmune thyroiditis.
OBJECTIVE Selenium ( Se ) in the form of selenocysteine is an essential component of the family of the detoxifying enzymes glutathione peroxidase ( Gpx ) and of the iodothyronine selenodeiodinases that catalyse the extrathyroidal production of tri-iodothyronine ( T(3 ) ) . Thus , Se deficiency may seriously influence the generation of free radicals , the conversion of thyroxine ( T(4 ) ) to T(3 ) and the autoimmune process . Therefore , we performed a r and omised , placebo-controlled prospect i ve study to investigate the effects of Se treatment on patients with autoimmune thyroiditis ( AIT ) . DESIGN AND METHODS Sixty five patients aged 22 - 61 years ( median age 48 years ) with AIT were recruited into two groups . Group I ( Gr I ) ( n=34 ) was treated with selenomethionine ( Seme ) 200 microg , plus L-thyroxine ( LT(4 ) ) to maintain TSH levels between 0.3 - 2.0 mU/l , whereas group II ( Gr II ) ( n=31 ) received LT(4 ) plus placebo over a period of 6 months . Moreover , the pharmacokinetics of Seme  were studied in 10 patients and eight volunteers at baseline and 2 h , 4 h , 6 h and 24 h after oral administration of a 200 microg tablet of Seme . Finally , Se levels were measured at the end of the study in some patients of both groups and their results were correlated with thyroid hormone levels . RESULTS In the pharmacokinetics study , basal serum concentration of Se ( 75+/-6 microg/l ) was within the reference range ( 70 - 125 microg/l ) , it promptly increased at 2 h , peaked at 4 h ( 147+/-17 microg/l ; P<0.0001 ) and it was abundant in serum at 24 h. In Gr I , antibodies against thyroid peroxidase ( anti-TPO ) levels showed an overall decrease of 46 % at 3 months ( from 1875+/-1039 U/l to 1013+/-382 U/l ; P<0.0001 ) and of 55.5 % at 6 months . In Gr II the overall decrease of anti-TPO amounted to 21 % at 3 months and to 27 % at 6 months ( from 1758+/-917 U/l to 1284+/-410 U/l ; P<0.005 ) . There were no significant changes of antibodies against thyroglobulin levels between the groups . At the end of this study Se levels were found to be statistically significantly increased in Gr I ( n = 9/34 ) compared with Gr II ( n=11/31 ) ( 97+/-8.4 vs 79+/-8 ; P<0.01 ) but no correlation with thyroid hormone was found . CONCLUSIONS Seme is proven to be rapidly absorbed by the gastrointestinal tract . It appears to be useful as adjunctive therapy with LT(4 ) in the treatment of AIT . The exact mechanism(s ) is not very well determined , it might enhance the activity of detoxifying enzymes and enforce the defense against oxidative stress
Two systematic review s have evaluated controlled trials among patients with autoimmune thyroiditis and report that selenium supplementation decreases circulating thyroid autoantibodies .
The immunomodulatory effects of selenium might involve reducing proinflammatory cytokine release .
In Graves ’ disease , some , but not all , trials indicate that adjuvant selenium supplementation enhances the restoration of biochemical euthyroidism , and might benefit patients with mild Graves ’ orbitopathy .
The available evidence from trials does not support routine selenium supplementation in the st and ard treatment of patients with autoimmune thyroiditis or Graves ’ disease .
However , correction of moderate to severe selenium deficiency may offer benefits in preventing , as well as treating , these disorders .
Purpose of review This review provides an appraisal of recent evidence for or against selenium supplementation in patients with autoimmune thyroid diseases , and discusses possible effect mechanisms .
Recent findings Epidemiological data suggest an increased prevalence of autoimmune thyroid diseases under conditions of low dietary selenium intake .
However , clinical ly relevant effects of selenium supplementation , including improvement in quality of life , are more elusive .