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 .
Effects of administration of iron, iodine and simultaneous iron-plus-iodine on the thyroid hormone profile in iron-deficient adolescent Iranian girls
Objective : To investigate whether iron supplementation can improve thyroid hormone function in iron-deficient adolescent girls . Design : A double-blind r and omized intervention study . Setting : The study was performed from 2002 through 2003 in the Islamic Republic of Iran . Subjects:103 iron-deficient non-anaemic girls who fulfilled all inclusion criteria were included , and 94 subjects successfully completed the study . Interventions : Patients were r and omly assigned to one of four groups and treated with a single oral dose of 190 mg iodine plus 300 mg ferrous sulphate 5 times/week ( n=24 ) , 300 mg ferrous sulphate 5 times/week ( n=23 ) , a single oral dose of 190 mg iodine ( n=25 ) , or a placebo ( n=22 ) for 12 weeks . Results : All groups were comparable at baseline . After the intervention , there was a significant increase in ferritin and transferrin saturation in the iron+iodine group ( 17.6 vs 8.7 μg/dl , and 18.8 vs 7.2 % , respectively , P<0.001 for both ) and in the iron group ( P<0.001 for both ) . Urinary iodine doubled in the iron+iodine group and in the iodine group ( P<0.001 for both ) . Thyroid indices tT4 , tT3 and T3RU increased and reverse RT3 decreased in the iron+iodine group ( 10 vs 8.9 μg/dl , P < 0.001 ; 143 vs 138 μg/dl , P<0.05 ; 32.3 vs 28.4 % , P<0.001 and 24.8 vs 44.2 ng/dl , P<0.001 , respectively ) and in the iron group . These two groups did not differ for any of the four indices , but both differed significantly from the iodine and placebo groups . Conclusions : Our results indicate that improvement of iron status was accompanied by an improvement in some indices of thyroid hormones . Sponsorship : This study was supported by the Dean of Research Affairs of the Tehran University of Medical Sciences
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 .