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 .
Primary school children from northeast Thailand are not at risk of selenium deficiency.
Selenium has important roles as an antioxidant , in thyroid hormone metabolism , redox reactions , reproduction and immune function , but information on the selenium status of Thai children is limited . We have assessed the selenium status of 515 northeast Thai children ( 259 males ; 256 females ) aged 6 to 13 years from 10 rural schools in Ubon Ratchthani province .  Serum selenium ( n=515 ) was analyzed by Graphite Furnace Atomic Absorption Spectrophotometry and dietary selenium intake by Hydride Generation Absorption Spectrophotometry from one-day duplicate diet composites , from 80 ( 40 females ; 40 males ) r and omly selected children . Inter-relationships between serum selenium and selenium intakes , and other biochemical micronutrient indices were also examined . Mean ( SD ) serum selenium  was 1.46 ( 0.24 ) micro mol/L. Concentrations were not affected by infection or haemoglobinopathies , but were dependent on school ( P < 0.001 ) , sex ( P=0.038 ) , and age group ( P=0.003 ) , with serum zinc as a significant covariate . None of the children had serum selenium concentrations indicative of clinical selenium deficiency ( i.e. < 0.1 micro mol/L ) . Significant correlations existed between serum selenium and serum zinc ( r= 0.216 ; P < 0.001 ) , serum retinol ( r = 0.273 ; P < 0.001 ) , urinary iodine ( r = -0.110 ; P = 0.014 ) , haemoglobin ( r = 0.298 ; P < 0.001 ) , and haematocrit ( r = 0.303 ; P < 0.001 ) . Mean ( SD ) dietary selenium intake was 46 ( 22 ) micro g/d . Children with low serum selenium concentrations had a lower mean selenium intake than those with high serum selenium concentrations ( 38 + /- 17 vs.51 + /- 24 micro g/d ; P < 0.010 ) . In conclusion , there appears to be no risk of selenium deficiency among these northeast Thai children
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 .