human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: 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 
    Output:
    
agent
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 .
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: 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 
    Output:
    