Although observational evidence suggests that concentrations of selenium , zinc , and iron are positively associated with iodine status , data from r and omized controlled trials fail to confirm this relationship .
Context The metabolism of thyroid hormones , which are essential for normal development , involves many proteins and enzymes .
It requires iodine as a key component but is also influenced by several other micronutrients , including selenium , zinc , iron , and vitamin A. Objective This systematic review was design ed to investigate the effect of micronutrient status and supplementation on  iodine status and thyroid hormone concentrations .
Urine Selenium Changes During Pregnancy Do Not Correlate with Thyroid Autoantibodies in a Mildly Iodine Deficient Population
Selenium ( Se ) is a key component of iodinases ; higher Se levels are associated with lower titers of antithyroid peroxidase antibodies ( anti-TPO ) . Pregnancy exerts profound effects on thyroid function and autoimmunity . To assess the relationship of urine Se levels with thyroid function and autoimmunity in pregnant women residing in Athens , Greece , we studied prospect ively 47 euthyroid women in uncomplicated singleton pregnancies ( mean age + SD : 30 + 5 years ) in each trimester , measuring urine Se levels , urine iodine , plasma thyrotropin ( TSH ) , free thyroxine and triiodothyronine ( FT4 and FT3 ) , as well as levels of anti-TPO antibodies . Changes of the measured parameters were assessed over each trimester ; thyroid parameters were assessed with relation to Se levels . Urine Se dropped by the third trimester , whereas urine iodine did not change appreciably during pregnancy . TSH and anti-TPO did not show appreciable changes ; FT4 and FT3 gradually decreased as the pregnancy advanced . No relationship between urine Se levels and anti-TPO was found . During pregnancy , changes in urine Se levels accompany mild changes in thyroid function . However , we did not find some association between these changes and thyroid autoimmune activity over this period , probably because the effect of Se on thyroid autoimmunity may only become apparent in case of excess Se fortification
Although observational evidence suggests that concentrations of selenium , zinc , and iron are positively associated with iodine status , data from r and omized controlled trials fail to confirm this relationship .
Context The metabolism of thyroid hormones , which are essential for normal development , involves many proteins and enzymes .
It requires iodine as a key component but is also influenced by several other micronutrients , including selenium , zinc , iron , and vitamin A. Objective This systematic review was design ed to investigate the effect of micronutrient status and supplementation on  iodine status and thyroid hormone concentrations .