Effect of iodine and selenium upon thyroid function. Selenium, zinc, and thyroid hormones in healthy subjects Selenium and iodine supplementation: effect on thyroid function of older New Zealanders. Effect of iron repletion and correction of iron deficiency on thyroid function in iron-deficient Iranian adolescent girls. Efficacy and safety of iodine in the postpartum period in an area of mild iodine deficiency. The Relationship Between Iron Status and Thyroid Hormones in Adolescents Living in an Iodine Deficient Area Effect of iron-, iodine-, and beta-carotene-fortified biscuits on the micronutrient status of primary school children: a randomized controlled trial. The Association between Selenium and Other Micronutrients and Thyroid Cancer Incidence in the NIH-AARP Diet and Health Study Low selenium status in the elderly influences thyroid hormones. Effects of administration of iron, iodine and simultaneous iron-plus-iodine on the thyroid hormone profile in iron-deficient adolescent Iranian girls Effects of selenomethionine supplementation on selenium status and thyroid hormone concentrations in healthy adults. Infant neurocognitive development is independent of the use of iodised salt or iodine supplements given during pregnancy. Minimal impact of excess iodate intake on thyroid hormones and selenium status in older New Zealanders. Efficacy of daily and weekly multiple micronutrient food-like tablets for the correction of iodine deficiency in Indonesian males aged 6-12 mo. Influence of selenium supplements on the post-traumatic alterations of the thyroid axis: a placebo-controlled trial Effect of low-dose selenium on thyroid autoimmunity and thyroid function in UK pregnant women with mild-to-moderate iodine deficiency The relationship between iron status and thyroid hormone concentration in iron-deficient adolescent Iranian girls.
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 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 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 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 BACKGROUND Iodine deficiency ( even moderate ) plays a major role in pregnancy associated goiter development , which is only party reversible after pregnancy . The prevalence of post partum thyroiditis is reported to be slightly lower in areas of iodine deficiency . Thus iodine supplementation may be effective in decreasing pregnancy associated increase in thyroid volume , but enhances the risk of increasing the prevalence of thyroid dysfunction in the post partum period . Therefore , we evaluated the effect of iodine supplementation ( with two different doses : 50 microg and 250 microg ) on the prevalence of post partum thyroiditis and the decrease in thyroid volume up to 8 months post partum in an area of mild iodine deficiency . PATIENTS AND METHODS Thyroid volume of 56 women was evaluated 5 days and 3 months after delivery ( study I ) . In an intervention study ( Study II ) 70 women were r and omized to receive 50 or 250 microg of potassium iodide for a period of 8 months post partum beginning five days after delivery . Thyroid volume , the echogenecity of the thyroid gl and , thyroid hormone parameters ( T4 , T3 , fT4 , TSH ) and thyroid antibodies ( TPO and Tg-Ab ) were measured 5 days , 3 and 8 months after delivery . RESULTS A total number of 11 women developed postpartum thyroid dysfunction : 4 women developed manifest thyroid dysfunction ( 3 hyperthyroidism and 1 hypothyroidism ) 3 months post partum . The remaining seven had sub clinical hypo- or hyperthyroidism . All changes were clinical ly mild and transient as evidence d by normalization of thyroid hormone parameters on reexamination at 8 months . Among the eleven , 6 women in the 50 microg iodine group and 5 women of the 250 microg iodine group developed thyroid dysfunction , suggesting that the iodine dose did not affect post partum thyroiditis . The administration of only 50 microg iodine was associated with a significant fall of thyroid size already 3 months after delivery ( 25.4 + /- 1.5 ml ( mean + /- sem ) to 18.2 + /- 1.25 p < 0.001 ) . The application of 250 microg iodine was equally effective . 8 months post partum a slight but further decrease could be demonstrated . On the other h and , in study I no significant reduction in thyroid volume was observed in women receiving no supplementary iodine ( thyroid volume at delivery 29 + /- 2.2 ml ; at 3 months 27.5 + /- 3.0 ml . CONCLUSION The administration of supplementary iodine ( up to 250 microg ) to an unselected population , residing in an area of mild iodine deficiency , in the post partum period is save as indicated by a prevalence of 5.7 % manifest thyroid dysfunction . These changes are clinical ly mild and transient . Even the amount of 50 microg of iodine supplementation seems to by very efficient in reducing pregnancy associated increments in thyroid volume 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 BACKGROUND Deficiencies of iron , iodine , and vitamin A are prevalent worldwide and can affect the mental development and learning ability of schoolchildren . OBJECTIVE The aim of this study was to determine the effect of micronutrient-fortified biscuits on the micronutrient status of primary school children . DESIGN Micronutrient status was assessed in 115 children aged 6 - 11 y before and after consumption of biscuits ( fortified with iron , iodine , and beta-carotene ) for 43 wk over a 12-mo period and was compared with that in a control group ( n = 113 ) who consumed nonfortified biscuits .  Cognitive function , growth , and morbidity were assessed as secondary outcomes . RESULTS There was a significant between-group treatment effect on serum retinol , serum ferritin , serum iron , transferrin saturation , and urinary iodine ( P < 0.0001 ) and in hemoglobin and hematocrit ( P < 0.05 ) . The prevalence of low serum retinol concentrations ( < 0.70 micromol/L ) decreased from 39.1 % to 12.2 % , of low serum ferritin concentrations ( < 20 microg/L ) from 27.8 % to 13.9 % , of anemia ( hemoglobin < 120 g/L ) from 29.6 % to 15.6 % , and of low urinary iodine concentrations ( < 100 microg/L ) from 97.5 % to 5.4 % . There was a significant between-group treatment effect ( P < 0.05 ) in cognitive function with the digit span forward task ( short-term memory ) . Fewer school days were missed in the intervention than in the control group because of respiratory- ( P = 0.097 ) and diarrhea-related ( P = 0.013 ) illnesses . The intervention had no effect on anthropometric status [ corrected ] . CONCLUSIONS Fortified biscuits result ed in a significant improvement in the micronutrient status of primary school children from a poor rural community and also appeared to have a favorable effect on morbidity and cognitive function [ corrected ] Background Selenium is an essential trace element that is important for thyroid hormone metabolism and has antioxidant properties which protect the thyroid gl and from oxidative stress . The association of selenium , as well as intake of other micronutrients , with thyroid cancer is unclear . Methods We evaluated associations of dietary selenium , beta-carotene , calcium , vitamin D , vitamin C , vitamin E , folate , magnesium , and zinc intake with  thyroid cancer  risk in the National Institutes of Health – American Association of Retired Persons Diet and Health Study , a large prospect i ve cohort of 566,398 men and women aged 50–71 years in 1995–1996 . Multivariable-adjusted Cox proportional hazards regression was used to examine associations between dietary intake of micronutrients , assessed using a food frequency question naire , and thyroid cancer cases , ascertained by linkage to state cancer registries and the National Death Index . Results With the exception of vitamin C , which was associated with an increased risk of thyroid cancer ( HRQ5 vs Q1 , 1.34 ; 95 % CI , 1.02–1.76 ; Ptrend , < 0.01 ) , we observed no evidence of an association between quintile of selenium ( HRQ5 vs Q1 , 1.23 ; 95 % CI , 0.92–1.65 ; Ptrend , 0.26 ) or other micronutrient intake and thyroid cancer . Conclusion Our study does not suggest strong evidence for an association between dietary intake of selenium or other micronutrients  and thyroid cancer risk . More studies are needed to clarify the role of selenium and other micronutrients in thyroid carcinogenesis 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 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 BACKGROUND Selenium , a potential cancer prevention agent currently being tested against prostate cancer in the Selenium and Vitamin E Cancer Prevention Trial ( SELECT ) , plays an integral role in thyroid metabolism . The effects of long-term selenium supplementation on thyroid hormone concentrations are unknown . OBJECTIVE The objective was to investigate the effects of long-term selenium supplementation on thyroid hormone concentrations . DESIGN Twenty-eight healthy adults took 200 microg selenomethionine/d for 28 mo . The thyroid hormones triiodothyronine ( T3 ) , thyroxine ( T4 ) , and thyrotropin ( TSH ) were measured in plasma for 4 mo before supplementation and quarterly during supplementation . The assay methods were changed mid study ; the results of the 2 methods were not comparable . Therefore , one analysis was conducted based on the results of the first method , and a second analysis was based on all of the data , adjusted for the change . Serial data collection permitted a test for trends rather than simply a difference between initial and final values . RESULTS By 9 mo , mean ( + /-SEM ) plasma selenium concentrations had increased from 1.78 + /- 0.07 micromol/L at baseline to 2.85 + /- 0.11 micromol/L for men and from 1.64 + /- 0.04 to 3.32 + /- 0.1.2 micromol/L for women . T3 concentrations in men increased 5 % per year ( P = 0.01 ) . T4 and TSH concentrations were unchanged . CONCLUSIONS Selenium supplementation produced no clinical ly significant changes in thyroid hormone concentrations . A small but statistically significant increase in T3 concentrations was noted in men , with no corresponding decreases in TSH . A subset of SELECT subjects might be monitored periodically for changes during long-term selenium supplementation The benefits of iodine supplements during pregnancy remain controversial in areas with a mild-to-moderate iodine deficiency . The aim of the present study was to determine the effect of improving iodine intakes , with iodised salt ( IS ) or iodine supplements , in pregnant Spanish women . A total of 131 pregnant women in their first trimester were r and omly assigned to three groups : ( 1 ) IS in cooking and at the table , ( 2 ) 200 μg potassium iodide (KI)/d or ( 3 ) 300 μg KI/d . No differences were found in thyroid-stimulating hormone ( TSH ) , free thyroxine ( FT4 ) , free triiodothyronine ( FT3 ) or thyroid volume ( TV ) between the three groups . Regardless of the group in which women were included , those who had been taking IS for at least 1 year before becoming pregnant had a significantly lower TV in the third trimester ( P= 0.01 ) and a significantly higher urinary iodine in the first ( 173.7 ( sd 81.8 ) v. 113.8 ( sd 79.6 ) μg/l , P= 0.001 ) and third trimesters ( 206.3 ( sd 91.2 ) v. 160.4 ( sd 87.7 ) μg/l , P= 0.03 ) . Also , no differences were seen in TSH , FT4 or FT3 . Children 's neurological development was not significantly associated with the consumption of IS for at least 1 year before becoming pregnant and no differences were found according to the treatment group . In conclusion , in pregnant women with insufficient iodine intake , the intake of IS before becoming pregnant was associated with a better maternal thyroid function . The form of iodide intake was not associated with maternal thyroid function or children 's neurological development 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 Infants are highly vulnerable to iodine deficiency , and little data exist on the effect of multiple micronutrient supplementation on their iodine status . OBJECTIVE We aim ed to compare the efficacy of daily and weekly multiple micronutrient food-like tablets ( foodLETs ) on increasing iodine status among infants . DESIGN In a double-blind , placebo-controlled trial , 133 Indonesian males aged 6 - 12 mo were r and omly assigned to 1 of 4 groups : a daily multiple-micronutrient foodLET providing the Recommended Nutrient Intake (RNI)(DMM ) , a weekly multiple-micronutrient foodLET providing twice the RNI ( WMM ) , a daily 10-mg Fe foodLET ( DI ) , or placebo .  Urinary iodine ( UI ) concentrations were measured at baseline and at 23 wk . RESULTS At baseline , the average UI concentration ( 1.37 micromol/L ) was within the normal range , and 30.8 % of subjects had iodine deficiency ( UI < 0.79 micromol/L ) . At 23 wk , the DMM group had the highest increment in UI ; however , after adjustment for initial UI , the changes in UI were not significantly different between the 4 groups ( P = 0.39 ) . Initial UI correlated inversely with the changes in UI ( P < 0.001 ) . The DMM group had the greatest reduction and increment in the proportion of iodine-deficient infants and in infants with iodine excess , respectively ; however , no significant difference was found in these proportions ( P = 0.13 and P = 0.42 ) between the 4 groups . CONCLUSION Daily consumption of a multiple-micronutrient foodLET providing the RNI during infancy may be one strategy to improve iodine status Abstract Objective : To investigate whether early selenium ( Se ) supplementation can modify the post-traumatic alterations of thyroid hormone metabolism , since the first week after trauma is characterised by low plasma Se and negative Se balances . Design : Prospect i ve , placebo-controlled r and omised supplementation trial . Setting : Surgical ICU in a tertiary university hospital . Patients : Thirty-one critically ill trauma patients aged 42±16 years ( mean±SD ) , with severe multiple injury ( Injury Severity Score 30±7 ) . Intervention : Supplementation during the first 5 days after injury with either Se or placebo . The selenium group was further r and omised to receive daily 500 µg Se , with or without 150 mg α-tocopherol ( AT ) and 13 mg zinc supplements . The placebo group received the vehicle . Circulating Se , AT , zinc , and thyroid hormones were determined on D0 (= day 0 , admission ) , D1 , D2 , D5 , D10 , and D20 . Results : Plasma Se , low on D0 , normalised from D1 in the  selenium group ; total T4 and T3 increased more and faster after D2 ( P=0.04 and 0.08 ) , reverse T3 rising less between D0 and D2 ( P=0.05 ) . Conclusions : Selenium supplements increased the circulating Se levels . Supplementation was associated with modest changes in thyroid hormones , with an earlier normalisation of T4 and reverse T3 plasma levels . The addition of AT and zinc did not produce any additional change 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 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 .