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 .
The relationship between iron status and thyroid hormone concentration in iron-deficient adolescent Iranian girls.
Extensive data from animal and human studies indicate that iron deficiency impairs thyroid metabolism . The aim of this study was to determine thyroid hormone status in iron-deficient adolescent girls . By stepwise r and om sampling from among all public high schools for girls in Lar and its vicinity in southern Iran , 103 out of 431 iron deficient subjects were selected . Urine and serum sample s were collected and assayed for urinary iodine and serum ferritin , iron , total iron binding capacity ( TIBC ) , thyroid stimulating hormone ( TSH ) , thyroxine ( T4 ) , triiodothyronine ( T3 ) , free thyroid hormones ( fT4 and fT3 ) , triiodothyronine resin uptake ( T3RU ) , reverse triiodothyronine ( rT3 ) , selenium and albumin concentrations . Hematological indices for iron status confirmed that all subjects were iron-deficient . There was a significant correlation between T4 and ferritin ( r = 0.52 , P < 0.001 ) and between TSH and ferritin ( r = -0.3 , P < 0.05 ) . Subjects with low serum ferritin had a higher ratio of T3/T4 ( r = -0.42 , P < 0.01 ) . Using stepwise regression analysis , only ferritin contributed significantly to the rT3 concentration ( r = -0.35 , P < 0.01 ) . The results indicate that the degree of iron deficiency may affect thyroid hormone status in iron-deficient adolescent girls
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 .