title: The Effect of Vitamin A Supplementation on Thyroid Function in Premenopausal Women Addition of microencapsulated iron to iodized salt improves the efficacy of iodine in goitrous, iron-deficient children: a randomized, double-blind, controlled trial. A cross-sectional survey of urinary iodine status in Latvia. Dual fortification of salt with iodine and iron: a randomized, double-blind, controlled trial of micronized ferric pyrophosphate and encapsulated ferrous fumarate in southern India. Treatment of iron deficiency in goitrous children improves the efficacy of iodized salt in Côte d'Ivoire. Randomized controlled trial of the effect of selenium supplementation on thyroid function in the elderly in the United Kingdom. Vitamin A supplementation in iodine-deficient African children decreases thyrotropin stimulation of the thyroid and reduces the goiter rate. Anemia, Iron Deficiency and Iodine Deficiency among Nepalese School Children Effect of low-dose selenium on thyroid autoimmunity and thyroid function in UK pregnant women with mild-to-moderate iodine deficiency Association of selenium with thyroid volume and echostructure in 35- to 60-year-old French adults. The relationship between iron status and thyroid hormone concentration in iron-deficient adolescent Iranian girls. Primary school children from northeast Thailand are not at risk of selenium deficiency. Urine Selenium Changes During Pregnancy Do Not Correlate with Thyroid Autoantibodies in a Mildly Iodine Deficient Population Selenium, zinc, and thyroid hormones in healthy subjects Concurrent micronutrient deficiencies are prevalent in nonpregnant rural and tribal women from central India. Double-Fortified Salt Is Efficacious in Improving Indicators of Iron Deficiency in Female Indian Tea Pickers123 Thyroglobulin as a marker of iodine nutrition status in the general population. Does selenium supplementation affect thyroid function? Results from a randomized, controlled, double-blinded trial in a Danish population. Urinary selenium and iodine during pregnancy and lactation. Iodine and iron status of pregnant women in Lubumbashi, Democratic Republic of Congo. Dual fortification of salt with iodine and micronized ferric pyrophosphate: a randomized, double-blind, controlled trial. High vitamin D status in younger individuals is associated with low circulating thyrotropin. Effect of iron repletion and correction of iron deficiency on thyroid function in iron-deficient Iranian adolescent girls. Minimal impact of excess iodate intake on thyroid hormones and selenium status in older New Zealanders. Selenium and iodine supplementation: effect on thyroid function of older New Zealanders. Effects of administration of iron, iodine and simultaneous iron-plus-iodine on the thyroid hormone profile in iron-deficient adolescent Iranian girls Effect of iodine and selenium upon thyroid function. Low selenium status in the elderly influences thyroid hormones. The Relationship Between Iron Status and Thyroid Hormones in Adolescents Living in an Iodine Deficient Area Correlations of Trace Element Levels in the Diet, Blood, Urine, and Feces in the Chinese Male
abstract: Objective : Vitamin A and its retinoid derivates play an important role in regulation of normal growth and development . Vitamin A has been shown to regulate thyroid hormone metabolism and inhibit thyroid-stimulating hormone ( TSH ) secretion via down regulation of TSH-β gene expression ; however , the effect of vitamin A on thyroid function in obese individuals who are at higher risk of sub clinical hypothyroidism is still unclear . In the present study we investigate the impact of vitamin A supplementation on thyroid function in obese women . Method : A 4-month r and omized , double blind controlled trial was conducted among 84 healthy women aged 17–50 years old : 56 were obese ( body mass index [ BMI ] 30–35 kg/m2 ) and 28 were nonobese ( BMI 18.5–24.9 kg/m2 ) . Obese women were r and omly allocated to receive either vitamin A ( 25,000 IU/d retinyl palmitate ) or placebo .  Nonobese women  received vitamin A. At baseline and 4 months after intervention , serum concentrations of TSH , total thyroxine ( T4 ) , total triiodothyronine ( T3 ) , retinol-binding protein ( RBP ) , and transthyretin ( TTR ) were measured . Results : Baseline concentrations of thyroid hormones , RBP and TTR were not significantly different between groups . Vitamin A caused a significant reduction in serum TSH concentrations in obese ( p = 0.004 ) and nonobese ( p = 0.001 ) groups . Serum T3 concentrations also increased in both obese and nonobese vitamin A – treated groups ( p < 0.001 ) . Serum T4 decreased in all 3 groups after treatment . The results showed a significant reduction in serum RBP in the obese group after vitamin A supplementation ( p = 0.007 ) , but no significant change was seen in serum TTR . Conclusions : Serum TSH concentrations in vitamin A – treated subjects were significantly reduced ; therefore , vitamin A supplementation might reduce the risk of sub clinical hypothyroidism in premenopausal women OBJECTIVE In many developing countries , children are at high risk for both goiter and anemia . Iron ( Fe ) deficiency adversely effects thyroid metabolism and reduces efficacy of iodine prophylaxis in areas of endemic goiter . The study aim was to determine if co-fortification of iodized salt with Fe would improve efficacy of the iodine in goitrous children with a high prevalence of anemia . DESIGN AND METHODS In a 9-month , r and omized , double-blind trial , 6 - 15 year-old children ( n=377 ) were given iodized salt ( 25 microg iodine/g salt ) or dual-fortified salt with iodine ( 25 microg iodine/g salt ) and Fe ( 1 mg Fe/g salt , as ferrous sulfate microencapsulated with partially hydrogenated vegetable oil ) . RESULTS In the dual-fortified salt group , hemoglobin and Fe status improved significantly compared with the iodized salt group ( P<0.05 ) . At 40 weeks , the mean decrease in thyroid volume measured by ultrasound in the dual-fortified salt group ( -38 % ) was twice that of the iodized salt group ( -18 % ) ( P<0.01 ) . Compared with the iodized salt group , serum thyroxine was significantly increased ( P<0.05 ) and the prevalence of hypothyroidism and goiter decreased ( P<0.01 ) in the dual-fortified salt group . CONCLUSION Addition of encapsulated Fe to iodized salt improves the efficacy of iodine in goitrous children with a high prevalence of anemia BACKGROUND AND OBJECTIVE A nationwide survey of schoolchildren was conducted to detect regional differences in urinary iodine excretion in Latvia and to compare the results with data from the newborn thyroid-stimulating hormone ( TSH ) screening data base as well with the results of a similar study performed in Latvia 10 years ago . MATERIAL S AND METHODS We conducted a cross-sectional school-based cluster survey of 915 children aged 9 - 12 years in 46 r and omly selected schools in all regions of Latvia .  Urine sample s , question naires on the consumption of iodized salt and information on socioeconomic status were collected . TSH levels in newborns were also measured . RESULTS The median creatinine-st and ardized urinary iodine concentration ( UIC ) in our study was 107.3μg/g Cr . UIC measurements indicative of mild iodine deficiency were present in 31.6 % , moderate deficiency in 11.9 % and severe deficiency in 2.8 % of the participants . The prevalence of iodine deficiency was the highest in the southeastern region of Latgale and the northeastern region of Vidzeme . The prevalence of TSH values > 5mIU/L followed a similar pattern . The self-reported prevalence of regular iodized salt consumption was 10.2 % . Children from urban schools had a significantly lower UIC than children from rural schools . CONCLUSIONS Our findings suggest that although the overall median UIC in Latvian schoolchildren falls within the lower normal range , almost 50 % of the schoolchildren are iodine deficient , especially in urban schools and in the eastern part of Latvia . The absence of a m and atory salt iodization program puts a significant number of children and pregnant women at risk BACKGROUND Dual fortification of salt with iodine and iron could be a sustainable approach to combating iodine and iron deficiencies . OBJECTIVE We compared the efficacy of dual-fortified salt ( DFS ) made by using 2 proposed contrasting formulas-one fortifying with iron as micronized ground ferric pyrophosphate ( MGFePP ) and the other with iron as encapsulated ferrous fumarate (EFF)-with the efficacy of iodized salt ( IS ) in schoolchildren in rural southern India . DESIGN After stability and acceptability testing , a double-blind , household-based intervention was conducted in 5 - 15-y-old children ( n = 458 ) r and omly assigned into 3 groups to receive IS or DFS with iron as MGFePP or EFF , both at 2 mg/g salt . We measured hemoglobin , iron status , and urinary iodine at baseline , 5 mo , and 10 mo . RESULTS Median serum ferritin and calculated median body iron improved significantly in the 2 groups receiving iron . After 10 mo , the prevalence of anemia decreased from 16.8 % to 7.7 % in the MGFePP group ( P < 0.05 ) and from 15.1 % to 5.0 % in the EFF group ( P < 0.01 ) . The median urinary iodine concentration increased significantly in the IS and EFF groups ( P < 0.001 ) but not in the MGFePP group . Losses of iodine in salt with 1.8 % moisture were high for MGFePP , whereas the EFF segregated in salt with 0.5 % moisture and caused color changes in some local foods . CONCLUSIONS Both DFSs were efficacious in reducing the prevalence of anemia and iron deficiency in school-age children . Local salt characteristics should be taken into consideration when choosing an iron fortificant for DFS to achieve optimal iodine stability and color BACKGROUND In many developing countries , children are at high risk of both goiter and iron deficiency anemia . Iron deficiency adversely affects thyroid metabolism and may reduce the efficacy of iodine prophylaxis in areas of endemic goiter . OBJECTIVE The aim of this study was to determine whether iron supplementation in goitrous , iron-deficient children would improve their response to iodized salt . DESIGN We conducted a r and omized , double-blind , placebo-controlled trial in 5 - 14-y-old children in Côte d'Ivoire . Goitrous , iron-deficient children ( n = 166 ) consuming iodized salt ( 10 - 30 mg I/kg salt at the household level ) were supplemented with either iron ( 60 mg Fe/d , 4 d/wk for 16 wk ) or placebo . At 0 , 1 , 6 , 12 , and 20 wk , we measured hemoglobin , serum ferritin , serum transferrin receptor , whole-blood zinc protoporphyrin , thyrotropin , thyroxine , urinary iodine , and thyroid gl and volume ( by ultrasonography ) . RESULTS Hemoglobin and iron status at 20 wk were significantly better after iron treatment than after placebo ( P < 0.05 ) . At 20 wk , the mean reduction in thyroid size in the iron-treated group was nearly twice that in the placebo group ( x + /- SD percentage change in thyroid volume from baseline : -22.8 + /- 10.7 % compared with -12.7 + /- 10.1 % ; P < 0.01 ) . At 20 wk , goiter prevalence was 43 % in the iron-treated group compared with 62 % in the placebo group ( P < 0.02 ) . There were no significant differences between groups in whole-blood thyrotropin or serum thyroxine at baseline or during the intervention . CONCLUSIONS Iron supplementation improves the efficacy of iodized salt in goitrous children with iron deficiency . A high prevalence of iron deficiency among children in areas of endemic goiter may reduce the effectiveness of iodine prophylaxis BACKGROUND Thyroid function depends on the essential trace mineral selenium , which is at the active center of the iodothyronine deiodinase enzymes that catalyze the conversion of the prohormone thyroxine ( T(4 ) ) to the active form of thyroid hormone , triiodothyronine ( T(3 ) ) . OBJECTIVE Because selenium intake in the United Kingdom has fallen during the past 25 y , we wanted to determine whether current selenium status might be limiting conversion of T(4 ) to T(3 ) in the elderly , in whom marginal hypothyroidism is relatively common . DESIGN We investigated the effect of selenium supplementation in a double-blind , placebo-controlled trial in 501 elderly UK volunteers . Similar numbers of men and women from each of 3 age groups , 60 - 64 y , 65 - 69 y , and 70 - 74 y , were r and omly allocated to receive 100 , 200 , or 300 microg Se/d as high-selenium yeast or placebo yeast for 6 mo . As part of the study , plasma selenium , thyroid-stimulating hormone , and total and free T(3 ) and T(4 ) were measured . Data from 368 euthyroid volunteers who provided blood sample s at baseline and 6 mo were analyzed . RESULTS Although selenium status at baseline correlated weakly with free T(4 ) ( r = -0.19 , P < 0.001 ) and with the ratio of free T(3 ) to free T(4 ) ( r = 0.12 , P = 0.02 ) , we found no evidence of any effect of selenium supplementation on thyroid function , despite significant increases in plasma selenium . However , baseline plasma selenium in our study ( x : 91 microg/L ) was somewhat higher than in previous supplementation studies in which apparently beneficial effects were seen . CONCLUSION We found no indication for increasing selenium intake to benefit T(4 ) to T(3 ) conversion in the elderly UK population BACKGROUND Vitamin A ( VA ) deficiency ( VAD ) and iodine deficiency ( ID ) often coexist in children in Africa . VAD may affect thyroid function and the response to iodine prophylaxis . OBJECTIVE The aim was to investigate the effects of supplementation with iodine or VA alone , and in combination , in children with concurrent VAD and ID . DESIGN A 6-mo r and omized , double-blind , 2 x 2 intervention trial was conducted in 5 - 14 y-old South African children ( n = 404 ) , who , on average , had mild-to-moderate VAD and ID . At baseline and after 3 mo , children received 1 ) iodine ( 191 mg I as oral iodized oil ) + placebo ( IS group ) , 2 ) VA ( 200000 IU VA as retinyl palmitate ) + placebo ( VAS group ) , 3 ) both iodine and VA ( IS+VAS group ) , or 4 ) placebo . At baseline , 3 mo , and 6 mo , urinary iodine ( UI ) , thyroid volume , thyrotropin ( thyroid-stimulating hormone ; TSH ) , total thyroxine ( TT(4 ) ) , thyroglobulin , serum retinol ( SR ) , and retinol-binding protein ( RBP ) were measured . RESULTS SR and RBP increased significantly with VA supplementation ( P < 0.05 ) . For UI , SR , and RBP , there were no significant treatment interactions between iodine and vitamin A. The 3-factor and all three 2-factor interactions were significant for thyroid volume , TSH , and thyroglobulin ( P < 0.001 ) , whereas none of these interactions were significant for TT(4 ) . There was a clear effect of VAS without IS on TSH , thyroglobulin , and thyroid volume ; all 3 variables decreased significantly ( P < 0.05 ) . CONCLUSIONS Iodine prophylaxis is effective in controlling ID in areas of poor vitamin A status . VA supplements are effective in treating VAD in areas of mild ID and have an additional benefit-through suppression of the pituitary TSHbeta gene , VAS can decrease excess TSH stimulation of the thyroid and thereby reduce the risk of goiter and its sequelae Objectives To assess iodine and iron nutritional status among Nepalese school children . Methods A cross-sectional , community based study was conducted in the two districts , Ilam ( hilly region ) and Udayapur ( plain region ) of eastern Nepal . A total of 759 school children aged 6–13 y from different schools within the study areas were r and omly enrolled . A total of 759 urine sample s and 316 blood sample s were collected . Blood hemoglobin level , serum iron , total iron binding capacity and urinary iodine concentration was measured . Percentage of transferrin saturation was calculated using serum iron and total iron binding capacity values . Results The mean level of hemoglobin , serum iron , total iron binding capacity , transferrin saturation and median urinary iodine excretion were 12.29 ± 1.85 g/dl , 70.45 ± 34.46 μg/dl , 386.48 ± 62.48 μg/dl , 19.94 ± 12.07 % and 274.67 μg/L respectively . Anemia , iron deficiency and iodine deficiency ( urinary iodine excretion < 100 μg/L ) were present in 34.5 % , 43.4 % and 12.6 % children respectively . Insufficient urinary iodine excretion ( urinary iodine excretion < 100 μg/L ) was common in anemic and iron deficient children . Conclusions Iron deficiency and anemia are common in Nepalese children , whereas , iodine nutrition is more than adequate . Low urinary iodine excretion was common in iron deficiency and anemia Purpose Selenium is an essential trace mineral and a component of selenoproteins that are involved in the production of thyroid hormones and in regulating the immune response . We aim ed to explore the effect of low-dose selenium supplementation on thyroid peroxidase antibody ( TPO-Ab ) concentration and thyroid function in pregnant women from a mild-to-moderate iodine-deficient population . Methods Sample s and data were from a secondary analysis of Selenium in PRegnancy INTervention ( SPRINT ) , a double-blind , r and omized , placebo-controlled study that recruited 230 women with singleton pregnancies from a UK antenatal clinic at 12 weeks of gestation . Women were r and omized to receive 60 µg/day selenium or placebo until delivery . Serum thyroid peroxidase antibodies ( TPO-Ab ) , thyrotropin ( TSH ) and free thyroxine ( FT4 ) were measured at 12 , 20 and 35 weeks and thyroglobulin antibodies ( Tg-Ab ) at 12 weeks . Results 93.5 % of participants completed the study  . Se supplementation had no more effect than placebo in decreasing TPO-Ab concentration or the prevalence of TPO-Ab positivity during the course of pregnancy . In women who were either TPO-Ab or Tg-Ab negative at baseline ( Thy-Ab−ve ) , TSH increased and FT4 decreased significantly throughout gestation ( P < 0.001 ) , with no difference between treatment groups . In women who were Thy-Ab+ve at baseline , TSH tended to decrease and was lower than placebo at 35 weeks ( P = 0.050 ) . FT4 fell more on Se than placebo supplementation and was significantly lower at 35 weeks ( P = 0.029 ) . Conclusions Low-dose selenium supplementation in pregnant women with mild-to-moderate deficiency had no effect on TPO-Ab concentration , but tended to change thyroid function in Thy-Ab+ve women OBJECTIVE To investigate the relationship between selenium status , thyroid Volume and gl and echostructure . DESIGN Cross-sectional . METHODS In 792 men ( 45 - 60 Years ) and 1108 women ( 35 - 60 Years ) from the SU.VI.MAX study , thyroid Volume and gl and echostructure were determined ultrasonographically . At baseline , thyrotropin , free thyroxine , selenium , zinc , alpha-tocopherol , beta-carotene , retinol , urinary iodine and thiocyanate concentrations were measured . Alcohol consumption , smoking , and menopausal status were assessed by a question naire . A stepwise linear and a logistic regression model were used , adjusting for antioxidant vitamins , trace elements status and age . RESULTS In women , there was an inverse association between selenium status and thyroid Volume ( P=0.003 ) . A protective effect of selenium against goiter ( odds ratio (OR)=0.07 , 95 % confidence interval (CI)=0.008 - 0.6 ) and thyroid tIssue damage ( OR=0.2 , 95 % CI=0.06 - 0.7 ) was observed . There was no evidence of an association between menopausal status and other antioxidant elements , thyroid Volume or thyroid hypoechogenicity . Smoking , but not alcohol consumption , was associated with an increased risk of thyroid enlargement in women ( OR=3.94 , 95 % CI=1.64 - 9.48 ) . No association between thyroid Volume , thyroid structure or selenium was found in men . CONCLUSION Our findings suggest that selenium may protect against goiter . Selenium was related to thyroid echostructure , suggesting it may also protect against autoimmune thyroid disease 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 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 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 Iodothyronine 5′ deiodinase , which is mainly responsible for peripheral T3 production , has recently been demonstrated to be a selenium (Se)-containing enzyme . The structure of nuclear thyroid hormone receptors contains Zinc ( Zn ) ions , crucial for the functional properties of the protein . In the elderly , reduced peripheral conversion of T4 to T3 with a lower T3/T4 ratio and overt hypothyroidism are frequently observed . We measured  serum Se and RBC GSH-Px ( as indices of Se status ) , circulating and RBC Zinc ( as indices of Zn status ) , thyroid hormones and TSH  in 109 healthy euthyroid subjects ( 52 women , 57 men ) , carefully selected to avoid abnormally low thyroid hormone levels induced by acute or chronic diseases or calorie restriction . The subjects were subdivided into three age groups . To avoid under- or malnutrition conditions , dietary records were obtained for a sample of 24 subjects , r and omly selected and representative of the whole population for age and sex .  Low T3/T4 ratios and reduced Se and RBC GSH-Px activity were observed only in the older group . A highly significant linear correlation between the T3/T4 ratio and indices of Se status was observed in the older group of subjects ( r=0.54;p<0.002 , for Se;r=0.50;p<0.002 , for RBC GSH-Px ) . Indices of Zn status did not correlate with thyroid hormones , but RBC Zn was decreased in older as compared with younger subjects . We concluded that reduced peripheral T4 conversion is related to impaired Se status in the elderly OBJECTIVE The existence of concurrent micronutrient deficiencies in Indian women of reproductive age has received little attention . This study aim ed to comprehensively assess the micronutrient status of nonpregnant rural and tribal women 18 - 30 y from central India . METHODS Participants ( n = 109 ) were r and omly selected using a stratified ( rural-tribal ) proportionate-to- population size cluster sampling method from 12 subcenters in Ramtek block , Nagpur . Sociodemographic , anthropometric , dietary , and biochemical data , including blood and urine sample s , were obtained . RESULTS Tribal and rural women had similar sociodemographic characteristics and anthropometric status ; 63 % of women had a body mass index < 18.5 kg/m(2 ) . The median urinary iodine concentration was 215 μg/L ( IQR : 127 , 319 ) . The mean ( SD ) concentration of hemoglobin , serum zinc , retinol , and folate was 112 ( 13 ) g/L , 10.8 ( 1.6 ) μmol/L , 1.2 ( 0.3 ) μmol/L , 18.4 ( 8.4 ) nmol/L , respectively , with a geometric mean serum vitamin B(12 ) concentration of 186 pmol/L. The percentage of women with low values for hemoglobin ( < 120 g/L ) , serum zinc ( < 10.7 μmol/L ) , vitamin B(12 ) ( < 148 pmol/L ) , retinol ( < 0.7 μmol/L ) , and folate ( < 6.8 nmol/L ) was 66 % , 52 % , 34 % , 4 % , and 2 % , respectively . Tribal women had a higher prevalence of zinc deficiency ( 58 % versus 39 % , P = 0.054 ) and concurrent deficiency of any two micronutrients ( 46 % versus 26 % ; P = 0.034 ) , including zinc and anemia ( 38 % versus 21 % , P = 0.024 ) . CONCLUSION Zinc , vitamin B(12 ) , and iron constitute the principal micronutrient deficiencies in these women . Existing supplementation programs should be extended to include 18- to 30-y-old nonpregnant women as the majority of childbearing occurs within this timeframe Poor iron status affects 50 % of Indian women and compromises work productivity , cognitive performance , and reproduction . Among the many strategies to reduce iron deficiency is the commercial fortification of iodized table salt with iron to produce a double-fortified salt ( DFS ) . The objective of this study was to test the efficacy of DFS in reducing iron deficiency in rural women of reproductive age from northern West Bengal , India . The participants were 212 women between 18 and 55 y of age who worked as full-time tea pickers on a large tea estate . Participants in the r and omized , controlled , double-blind study were assigned to use either DFS or a control iodized salt for 7.5 to 9 mo . The DFS was fortified with 3.3-mg ferrous fumarate ( 1.1-mg elemental iron ) per kg of iodized salt , whereas the control salt contained only iodine ( 47 mg/kg potassium io date ) , and both salt varieties were distributed gratis to the families of participants at 0.5 kg/mo for each 2 household members . At baseline , 53 % of participants were anemic ( hemoglobin < 120 g/L ) , 25 % were iron deficient ( serum ferritin < 12 μg/L ) , and 23 % were iron-deficient anemic . Also , 22 % had a transferrin receptor concentration > 8.6 mg/L and 22 % had negative ( < 0.0 mg/kg ) body iron stores . After 9 mo the participants receiving DFS showed significant improvements compared with controls in hemoglobin ( + 2.4 g/L ) , ferritin ( + 0.13 log10 μg/L ) , soluble transferrin receptor ( −0.59 mg/L ) , and body iron ( + 1.43 mg/kg ) , with change in status analyzed by general linear models controlling for baseline values . This study demonstrated that DFS is an efficacious approach to improving iron status and should be further evaluated for effectiveness in the general population . This trial was registered at clinical trials.gov as NCT01032005 OBJECTIVE The iodine status of a population is traditionally evaluated by either urinary iodine ( UI ) excretion or by some measure of thyroid volume and the prevalence of goitre . In this prospect i ve study of a m and atory iodization programme , we aim ed to evaluate serum thyroglobulin ( Tg ) as a marker of iodine status in the population . METHODS Two identical cross-sectional studies were performed before ( 1997 - 1998 , n=4649 ) and after ( 2004 - 2005 , n=3570 ) the initiation of the Danish iodization programme in two areas with mild and moderate iodine deficiency .  Serum Tg was measured from blood sample s. Thyroid volume was measured by ultrasonography . RESULTS Before iodization , the median serum Tg was considerably higher in moderate than in mild iodine deficiency . Iodization led to a lower serum Tg in all examined age groups . The marked pre-iodization difference in Tg level between the regions was eliminated . The prevalence of Tg above the suggested reference limit ( 40 microg/l ) decreased from 11.3 to 3.7 % ( P<0.0001 ) . Using bootstrapping , we demonstrated a higher efficacy of Tg than of thyroid volume to show a difference between pre- and post-iodization values . CONCLUSION We found serum Tg to be a suitable marker of iodine nutrition status in the population . The results may suggest that the Danish iodization programme has led to a sufficient iodine intake , even if the median UI excretion is still marginally low according to WHO criteria OBJECTIVE Selenium is present in the active site of proteins important for thyroid hormone synthesis and metabolism . The objective of this study is to investigate the effect of selenium supplementation in different doses on thyroid function , under conditions of suboptimal dietary selenium intake . DESIGN The Danish PREvention of Cancer by Intervention with SElenium pilot study ( DK-PRECISE ) is a r and omized , double-blinded , placebo-controlled trial . A total of 491 males and females aged 60 - 74 years were r and omized to 100 μg ( n=124 ) , 200 μg ( n=122 ) , or 300 μg ( n=119 ) selenium-enriched yeast or matching yeast-based placebo tablets ( n=126 ) . A total of 361 participants , equally distributed across treatment groups , completed the 5-year intervention period . METHODS Plasma sample s were analyzed for selenium and serum sample s for TSH , free triiodothyronine ( FT3 ) , and free thyroxine ( FT4 ) at baseline , and after 6 months , and 5 years of supplementation . RESULTS Plasma selenium concentrations increased significantly and dose-dependently in treatment groups receiving selenium ( P<0.001 ) . Serum TSH and FT4 concentrations decreased significantly and dose-dependently by 0.066 mIU/l ( P=0.010 ) and 0.11 pmol/l ( P=0.015 ) , respectively , per 100 μg/day increase , with insignificant differences between 6 months and 5 years . No significant effects were found for FT3 and FT3:FT4 ratio . CONCLUSIONS In euthyroid subjects , selenium supplementation minutely and dose-dependently affects thyroid function , when compared with placebo , by decreasing serum TSH and FT4 concentrations . Based on these findings , selenium supplementation is not warranted under conditions of marginal selenium deficiency . However , a role for selenium supplementation in the treatment of autoimmune thyroid diseases is still unresolved The New Zeal and environment is low in selenium and iodine , and is therefore ideally suited for the study of these anionic trace elements . The aim of this study was to determine urinary excretion of selenium and iodine during pregnancy and postpartum as part of an investigation of the influence of pregnancy and lactation on selenium metabolism in women of low selenium status . In a double-blind placebo-controlled study , 35 women in the earliest stages of pregnancy and 17 non-pregnant women were recruited in Dunedin , New Zeal and . Eighteen pregnant women received 50 microg selenium as L-selenomethionine , while the others received a placebo daily during pregnancy and 12 months postpartum . The non-pregnant women received the supplement , serving as a positive control . Blood sample s and twenty-four hour urine sample s were collected monthly during pregnancy and at 3 , 6 , and 12 months postpartum for analysis of selenium and iodine . Selenium content in plasma and urinary excretion of selenium fell during pregnancy ; however , total excretion of selenium was greater during pregnancy than postpartum . Urinary iodine excretion was much lower than reported previously in New Zeal and . Due to large intra- and inter-subject variability , no trends in iodide excretion were observed . Factors which influence urinary excretion of selenium include dietary intake , but more closely , plasma concentrations of selenium ( which is probably related to total selenium pool ) , creatinine excretion and therefore lean body mass , and glomerular filtration rate . The exact mechanism and sequence of events remains unclear and future studies incorporating new speciation techniques are necessary OBJECTIVE Adequate iodine and Fe intakes are imperative during pregnancy to prevent fetal defects , but such data are not available in the Democratic Republic of Congo . We aim ed to assess iodine and Fe status in pregnant women from Lubumbashi . DESIGN Cross-sectional study . We measured urinary iodine concentration ( UIC ) in r and om urine sample s using a modified S and ell – Kolthoff digestion method ; the WHO reference medians were used to classify iodine intake as deficient , adequate , more than adequate or excessive . Serum ferritin concentrations were measured by immunoenzymatic assay and considered insufficient when , 12 ng/ml . SETTING Maternity units from rural , semi-urban and urban areas of Lubumbashi , Democratic Republic of Congo . SUBJECTS Two hundred and twenty-five r and omly selected pregnant women attending prenatal consultation , seventy-five postpartum women and seventy-five non-pregnant women as controls . RESULTS Overall median UIC in pregnant women was 138 ( interquartile range : 105–172 ) mg/l , indicating iodine deficiency , whereas postpartum and nonpregnant women had adequate iodine intake : median UIC5144mg/l and 204mg/l , respectively . Median UIC values were lower in late pregnancy than in early pregnancy : in the first , second and third trimester respectively 255mg/l , 70mg/l and 88mg/l in the rural area ; 306mg/l , 166mg/l and 68mg/l in the semi-urban area ; and 203mg/l , 174mg/l and 99mg/l in the urban area . Fe was insufficient in 39 % of pregnant women compared with 21 % of non-pregnant and postpartum women . In the third trimester , deficiencies in both iodine and Fe were high : 40 % , 12 % and 18 % in the rural , semi-urban and urban areas , respectively . CONCLUSIONS Our data suggest that pregnant women are at risk of iodine and Fe deficiencies in Lubumbashi . Country policies fighting against iodine and Fe deficiencies during pregnancy should be reinforced BACKGROUND In many developing countries , children are at high risk for both goiter and anemia . In areas of subsistence farming in rural Africa , salt is one of the few regularly purchased food items and could be a good fortification vehicle for iodine and iron , provided that a stable yet bioavailable iron fortificant is used . OBJECTIVE We tested the efficacy of salt dual-fortified with iodine and micronized ferric pyrophosphate for reducing the prevalence of iodine and iron deficiencies in children . DESIGN In rural northern Morocco , we fortified local salt with 25 microg I ( as potassium io date ) /g salt and 2 mg Fe ( as micronized ferric pyrophosphate ; mean particle size = 2.5 microm)/g salt . After storage and acceptability trials , we compared the efficacy of the dual-fortified salt ( DFS ) with that of iodized salt in a 10-mo , r and omized , double-blind trial in iodine-deficient 6 - 15-y-old children ( n = 158 ) with a high prevalence of anemia . RESULTS After storage for 6 mo , there were no significant differences in iodine content or color lightness between the DFS and iodized salt . During the efficacy trial , the DFS provided approximately 18 mg Fe/d ; iron absorption was estimated to be approximately 2 % . After 10 mo of treatment in the DFS group , mean hemoglobin increased by 16 g/L ( P < 0.01 ) , iron status and body iron stores increased significantly ( P < 0.01 ) , and the prevalence of iron deficiency anemia decreased from 30 % at baseline to 5 % ( P < 0.001 ) . In both groups , urinary iodine ( P < 0.001 ) and thyroid volume ( P < 0.01 ) improved significantly from baseline . CONCLUSION A DFS containing iodine and micronized ferric pyrophosphate can be an effective fortification strategy in rural Africa BACKGROUND Vitamin D is an immunomodulator and may affect autoimmune thyroid diseases . Vitamin D has also been shown to influence thyrocytes directly by attenuating thyrotropin (TSH)-stimulated iodide uptake and cell growth . However , it is unclear how vitamin D status is related to TSH at the population level . The goal of the present study was to investigate the relationship between  vitamin D status and TSH levels according to thyroid autoantibodies in a population -based health survey in Thail and . METHODS A total of 2582 adults , aged 15 - 98 years , were r and omly selected according to the geographical region from the Thail and 4th National Health Examination Survey sample . By study design , the sexes were equally represented .  Serum levels of 25-hydroxyvitamin D [ 25(OH)D ] , TSH , the thyroid peroxidase antibody ( TPOAb ) , and the thyroglobulin antibody ( TgAb ) were measured in all subjects . RESULTS The mean age was 55.0±0.4 ( SE ) years . In subjects positive for serum TgAb , serum TSH levels were higher , whereas total serum 25(OH)D levels were lower . In addition , the prevalence of vitamin D insufficiency in TgAb-positive subjects was significantly higher than that observed in TPOAb- and TgAb-negative subjects , whether based on cutoff values of 20 or 30 ng/mL : 8.3 % vs. 5.6 % , p<0.05 ; or 47.6 % vs. 42.0 % , p<0.05 , respectively . However , vitamin D status was not associated with positive TPOAb and /or TgAb after controlling for sex and age . To explore the probable interaction between vitamin D status and age on serum TSH , analyses were performed according to age tertiles ; it was found that higher 25(OH)D levels were independently associated with lower TSH , but only in subjects in the lowest age tertile . CONCLUSIONS This population -based study showed that high vitamin D status in younger individuals is associated with low circulating TSH The aim of this study was to determine whether iron supplementation in iron-deficient adolescent girls would improve thyroid function . A double-blind clinical trial was performed in a region in southern I.R. Iran . A total of 103 iron deficient participants were chosen . In all , 94 participants successfully completed this study . Participants were r and omly assigned to one of two groups and treated with a 300 mg ferrous sulfate 5 times/week ( n = 47 ) and placebo 5 times/week ( n = 47 ) for 12 weeks . Blood sample s were collected and assayed for hemoglobin , hematocrit , serum ferritin , iron , total iron binding capacity ( TIBC ) , Thyroid stimulating hormone ( TSH ) , total thyroxine ( TT4 ) , total triiodothyronine ( TT3 ) , free thyroid hormones ( FT4 and FT3 ) , triiodothyronine resin uptake ( T3RU ) , reverse triiodothyronine ( rT3 ) , selenium and albumin concentrations . Statistical analysis was performed with parametric and non-parametric methods as appropriate . Data analysis revealed a significant increase in TT4 , TT3 , T3RU and a significant decrease in rT3 concentration in comparison to initial values in iron treated group ( 12 % , p<0.001 ; 3.5 % , p<0.001 ; 16 % , p<0.05 and 47 % , p<0.001 , respectively ) . At 12 week there were significant differences between control and placebo in TT4 , TT3 , T3RU and rT3 concentrations ( 9.9 vs 8.4 microg dL(-1 ) , 145.2 vs 130.4 microg dL(-1 ) , 32.5 vs 28.4 % and 23 vs 41 microg dL(-1 ) , respectively , all p<0.001 ) . Alterations in FT3 and TSH concentration were not significant , but concentration of FT4 revealed a significant difference between the beginning and the end of the study in iron treated group ( 10.3 vs 11.4 , p<0.001 ) . Iron supplementation improves some indices of thyroid function in iron-deficient adolescent girls OBJECTIVE Iodine deficiency has re-emerged in New Zeal and , while selenium status has improved . The aim of this study was to investigate the effects of excess iodine intake as io date on thyroid and selenium status . METHODS In a r and omized controlled trial on older people ( mean±s.d . 73±4.8 years ; n=143 ) , two groups received > 50 mg iodine as io date /day for 8 weeks because of supplement formulation error , either with 100 μg selenium ( Se+highI ) or without selenium ( highI ) . Four other groups received 80 μg iodine as io date /day with selenium ( Se+lowI ) or without selenium ( lowI ) , selenium alone ( Se+ ) , or placebo . Thyroid hormones , selenium status , and median urinary iodine concentration ( MUIC ) were compared at weeks 0 , 8 , and 4 weeks post-supplementation . RESULTS MUIC increased nine- and six-fold in Se+highI and highI groups , decreasing to baseline by week 12 . Plasma selenium increased in selenium-supplemented groups ( P<0.001 ) . The level of increase in whole blood glutathione peroxidase ( WBGPx ) in the Se+highI group was smaller than Se+ ( P=0.020 ) and Se+lowI ( P=0.007 ) groups . The decrease in WBGPX in the highI group was greater than other non-selenium-supplemented groups , but differences were not significant . Ten of 43 participants exposed to excess io date showed elevated TSH ( hypothyroidism ) at week 8 . In all but two , TSH had returned to normal by week 12 . In three participants , TSH decreased to < 0.10 mIU/l ( hyperthyroidism ) at week 8 , remaining low at week 12 . CONCLUSIONS Excess io date induced hypothyroidism in some participants and hyperthyroidism in others . Most abnormalities disappeared after 4 weeks . Excess io date reduced WBGPx activity and result ed in smaller increases in WBGPx after selenium supplementation BACKGROUND The New Zeal and population has both marginal selenium status and mild iodine deficiency . Adequate intakes of iodine and selenium are required for optimal thyroid function . OBJECTIVE The aim of the study was to determine whether low selenium and iodine status compromises thyroid function in an older New Zeal and population . DESIGN We investigated the effects of selenium and iodine supplementation in a double-blind , r and omized , placebo-controlled trial in 100 Dunedin volunteers aged 60 - 80 y. Participants received 100 microg Se/d as l-selenomethionine , 80 microg I , 100 microg Se + 80 microg I , or placebo for 3 mo . Thyroid-stimulating hormone ( TSH ) , free triiodothyronine ( T(3 ) ) , free thyroxine ( T(4 ) ) , thyroglobulin , plasma selenium , whole-blood glutathione peroxidase ( GPx ) activity , and urinary iodine concentrations ( UICs ) were measured . RESULTS Plasma selenium ( P < 0.0001 ) and whole-blood GPx activity ( P<0.0001 ) increased from baseline to week 12 in the selenium and selenium plus iodine groups in comparison with the placebo group . Median UIC at baseline was 48 microg/L ( interquartile range : 31 - 79 microg/L ) , which is indicative of moderate iodine deficiency . UIC increased in the iodine and selenium plus iodine groups and was significant only for the iodine group ( P = 0.0014 ) . Thyroglobulin concentration decreased by 24 % and 13 % of baseline in the iodine and selenium plus iodine groups in comparison with the placebo group ( P = 0.009 and P = 0.108 , respectively ) . No significant treatment effects were found for TSH , free T(3 ) , free T(4 ) , or ratio of T(3 ) to T(4 ) . CONCLUSIONS Additional selenium improved GPx activity but not the thyroid hormone status of older New Zeal and ers . Iodine supplementation alleviated the moderate iodine deficiency and reduced elevated thyroglobulin concentrations . No synergistic action of selenium and iodine was observed . The trial was registered at www.anzctr.org.au/registry/ as ACTRN012605000368639 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 Iodine is an essential element with unique role in organism : it is indispensable component of thyroid hormones . After binding with specific nuclear receptor , T3/T4 induce transcription of genetic code via mRNA and regulate proteo synthesis in most tissues . Thyroid hormones regulate rate of metabolic processes and consequently development of organism . Czech Republic was in past typical region with moderate to severe iodine deficiency . Therefore epidemiological survey was started in r and omly selected sample s of peoples . Thereafter a complex program of improving iodine supply was realized . Prompt effects of this changes were recorded , namely increase of ioduria and decrease of thyroid volume . Essential trace element selenium has a fundamental importance to the cell and body metabolism regulation by thyroid hormones . Activities of selenoenzymes deiodinases lead to the activation of prohormone T4 to active hormone T3 and the inactivation of T3 and of T4 , as well . There is unfortunately moderate to mild Se deficit in the CR . Average serum Se concentrations for the population s from 6 to 65 years are in the regions of the CR between 42 and 62 micrograms/l and urine Se values are between 8 and 15 micrograms/l . We have found statistically significant correlations among indexes of selenium status and indexes of thyroid hormone metabolism and function . Especially dangerous are concomitant deficiencies of both key elements for thyroid hormone metabolism -- I and Se -- from the point of thyroid hormone regulative functions 1 . Iodothyronine 5'-deiodinase , which is mainly responsible for peripheral triiodothyronine ( T3 ) production , has recently been demonstrated to be a selenium-containing enzyme . In the elderly , reduced peripheral conversion of thyroxine ( T4 ) to T3 and overt hypothyroidism are frequently observed . 2 . We measured  serum selenium and erythrocyte glutathione peroxidase ( as indices of selenium status ) , thyroid hormones and thyroid-stimulating hormone in 109 healthy euthyroid subjects ( 52 women , 57 men ) , carefully selected to exclude abnormally low thyroid hormone levels induced by acute or chronic diseases or calorie restriction . The subjects were subdivided into three age groups . To avoid conditions of under-nutrition or malnutrition , dietary records were obtained for a sample of 24 subjects , r and omly selected and representative of the whole population for age and sex . 3 . In order to properly assess the influence of selenium status on iodothyronine 5'-deiodinase type I activity , a double-blind placebo-controlled trial was also carried out on 36 elderly subjects , resident at a privately owned nursing home . 4 . In the free-living population , a progressive reduction of the T3/T4 ratio ( due to increased T4 levels ) and of selenium and erythrocyte glutathione peroxidase activity was observed with advancing age . A highly significant linear correlation between T4 , T3/T4 and selenium was observed in the population as a whole ( for T4 , R = -0.312 , P < 0.002 ; for T3/T4 ratio , R = 0.32 , P < 0.01 ) and in older subjects ( for T4 , R = -0.40 , P < 0.05 ; for T3/T4 ratio , R = 0.54 , P < 0.002 ) . 5 . The main result of the double-blind placebo-controlled trial was a significant improvement of selenium indices and a decrease in the T4 level in selenium-treated subjects ; serum selenium , erythrocyte glutathione peroxidase activity and thyroid hormones did not change in placebo-treated subjects . 6 . We concluded that selenium status influences thyroid hormones in the elderly , mainly modulating T4 levels BACKGROUND Iron may be only one of many nutritional factors that influence thyroid hormone metabolism in iodine-deficient areas . OBJECTIVE To evaluate the effect of iron status on thyroid hormone profile in adolescents living in a mild iodine-deficient area in Turkey . SUBJECTS Three hundred and thirty school-aged children with mean age 14 years were examined . METHODS Free triiodothyronine , free tetraiodothyronine and thyrotropin levels were analyzed by chemiluminescent enzyme immunoassay .  Hemoglobin and mean corpuscular volume were measured with a Hemocounter . Iron and total iron binding capacity concentration were determined by colorimetric photometric methods . Ferritin level was determined by immunoturbidimetry . RESULTS Thyroid hormone levels of the children with anemia were not significantly different compared to children without anemia . No significant correlation was found between thyroid hormones and iron status . CONCLUSION The thyroid hormone profile was not significantly affected in this area . This survey showed no correlation between iron status and thyroid hormone levels In order to explore the associations between trace elements in dietary intake and the other three biological media ( blood , urine , or feces ) and inter-element interactions among the latter , we simultaneously collected 72-h diet duplicates , whole blood , and 72-h urine and feces from 120 free-living healthy males in China . Correlations among the toxic ( cadmium [ Cd ] , lead [ Pb ] ) , and nutritionally essential ( zinc [ Zn ] , copper [ Cu ] , iron [ Fe ] , manganese [ Mn ] , selenium [ Se ] , iodine [ I ] ) elements were evaluated using Spearman rank correlation analysis based on analytical data determined by inductively coupled plasma-mass spectrometry . Dietary Cd intakes were highly correlated with the fecal Cd and blood Cd levels . Inverse correlations were found for Fe – Cd and Fe – Pb in both diet versus blood and diet versus feces . Cd – Zn and Cd – Se were significantly directly correlated in the urine and feces . Cd – Se and Pb – Se were negatively correlated in blood . In addition , there existed an extremely significant association between urinary Se and urinary I. Moreover , the other two highly direct correlations were found for Se – Fe and for I – Fe in urine . Improved knowledge regarding their mutual associations is considered to be of fundamental importance to underst and more the complex interrelationships in trace element metabolism
target: 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 .
background: 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 .