Earliest prevention of endemic goiter by iodine supplementation during pregnancy. Iodine prophylaxis using iodized salt and risk of maternal thyroid failure in conditions of mild iodine deficiency. Iodine supplementation in pregnancy and its effect on child cognition. Postpartum thyroid dysfunction in pregnant thyroid peroxidase antibody-positive women living in an area with mild to moderate iodine deficiency: is iodine supplementation safe? Serum thyroglobulin and urinary iodine concentration are the most appropriate indicators of iodine status and thyroid function under conditions of increasing iodine supply in schoolchildren in Benin. Comparison of two different doses of iodide in the prevention of gestational goiter in marginal iodine deficiency: a longitudinal study. Cognitive and motor functions of iodine-deficient but euthyroid children in Bangladesh do not benefit from iodized poppy seed oil (Lipiodol). Persistence of goiter despite oral iodine supplementation in goitrous children with iron deficiency anemia in Côte d'Ivoire. Efficacy and safety of iodine in the postpartum period in an area of mild iodine deficiency. Goiter prevalence, urinary iodine excretion, thyroid function and anti-thyroid function and anti-thyroid antibodies after 12 years of salt iodization in Shahriar, Iran. Effects of iodine supplementation during pregnancy on child growth and development at school age. Vitamin A supplementation in iodine-deficient African children decreases thyrotropin stimulation of the thyroid and reduces the goiter rate. Infant neurocognitive development is independent of the use of iodised salt or iodine supplements given during pregnancy. Efficacy of low oral doses of iodized oil in the control of iodine deficiency in Zaire. The effects of iodoprophylaxis on thyroid size during pregnancy. The Danish investigation on iodine intake and thyroid disease, DanThyr: status and perspectives. Iodine supplementation improves cognition in mildly iodine-deficient children. Direct iodine supplementation of infants versus supplementation of their breastfeeding mothers: a double-blind, randomised, placebo-controlled trial. The effect of iodine supplementation in pregnancy on early childhood neurodevelopment and clinical outcomes: results of an aborted randomised placebo-controlled trial Hypothyroid patients showing shortened responsiveness to oral iodized oil have paradoxically low serum thyroglobulin and low thyroid reserve. Thyroglobulin/thyrotropin ratio as a measure of thyroid damage. Selenium and iodine supplementation: effect on thyroid function of older New Zealanders. Effects of maternal iodine supplementation during pregnancy. Amelioration of some pregnancy-associated variations in thyroid function by iodine supplementation.
During pregnancy complex changes of maternal thyroid function occur and they are influenced by the maternal iodine supply . It has been demonstrated that with decreasing iodine supply maternal goiter and hypothyroxinemia as well as fetal and neonatal hypothyroidism become more prevalent . Therefore iodine supplementation during pregnancy is now strongly recommended also in areas of moderate iodine deficiency . To monitor the success of iodine supplementation and its theoretical risk of increasing the frequency of thyroid autoantibodies , we have investigated the thyroid volume , thyroid function , urinary iodine excretion and antibodies to thyroid peroxidase at 10 - 12 weeks of gestation and postpartum in 38 mothers receiving 300 micrograms potassium iodide/day and in 70 mothers without iodine supplementation .  In all of their newborns thyroid volume was determined by ultrasound . The thyrotropin ( TSH ) levels and antibodies to thyroid peroxidase ( TPO-ab ) in the neonates were measured in dried blood spots on filter paper from their newborn screening . Urinary iodine excretion was increased significantly after iodine supplementation in mothers ( p < 0.001 ) and their newborns ( < 0.05 ) . No hypo- or hyperthyroidism was observed in the mothers or newborns . Interestingly , no difference of maternal thyroid volumes was observed between the two groups after pregnancy , but the volumes of the thyroid gl and s in newborns of mothers who received iodine were significantly ( p < 0.004 ) lower ( 0.7 + /- 0.4 ml ) than in the control group ( 1.5 + /- 1.1 ml ) . There was no change in the frequency of TPO-ab in either group after pregnancy . In four mothers transplacental passage of these antibodies was documented by positive measurement in the blood sample of the newborn . This study documents that iodine supplementation during pregnancy in an area of moderate iodine deficiency results in a lower size of neonatal thyroid volume and that this supplementation was not accompanied by an increase in the frequency of TPO-ab CONTEXT Mild to moderate iodine deficiency during pregnancy can cause transient maternal hypothyroidism and impaired mental development of the progeny . These unfavorable effects are preventable by iodine supplementation . In Europe , however , less than 50 % pregnant women receive iodine-containing supplements , thus representing dietary iodized salt the only carrier of iodine for most women in this life stage . OBJECTIVE / DESIGN This longitudinal study is aim ed to investigate the effects of long-term iodized salt consumption on maternal thyroid function during gestation . PARTICIPANTS / OUTCOME MEASURES : We prospect ively evaluated thyroid function in 100 consecutive thyroperoxidase antibody-negative pregnant women from a mildly iodine-deficient area . Sixty-two women who had regularly used iodized salt for at least 2 yr prior to becoming pregnant and 38 who commenced iodized salt consumption upon becoming pregnant were classified as long-term ( LT ) and short-term ( ST ) iodine supplemented , respectively . RESULTS Long-term iodized salt consumption result ed in a very low prevalence of maternal thyroid failure ( MTF ) in LT women . Conversely , short-term iodine prophylaxis does not seem to protect against the risk of MTF , the prevalence of which was almost 6-fold higher in ST than LT women ( 36.8 % vs. 6.4 % ; chi(2 ) 14.7 , P < 0.0005 ; relative risk 5.7 , 95 % confidence interval 2.03 - 16.08 , P < 0.001 ) . The relative risk reduction amounted to 82.5 % , this measure indicating the extent to which long-term iodine prophylaxis using iodized salt would reduce the risk of MTF in ST women . CONCLUSIONS Prolonged iodized salt significantly improves maternal thyroid economy and reduces the risk of maternal thyroid insufficiency during gestation , probably because of a nearly restoring intrathyroidal iodine stores Maternal hypothyroidism and hypothyroxenemia due to iodine deficiency have been shown to affect development of the newborn negatively . Maternal iodine supplementation may therefore improve cognitive performance of the offspring , even in areas of mild-to-moderate iodine deficiency ( ID ) . Several iodine supplementation studies have been performed in mildly ID pregnant women in Europe . These studies have shown that iodine supplementation increases maternal urinary iodine ( UI ) excretion and reduces thyroid volume , as well as prevents increases in infant thyroid volume and thyroglobuline . However , r and omized controlled studies with long-term outcomes are lacking . Therefore , two trials were started in 2008 in areas of low iodine status ; one in Bangalore , India ( n=325 ) , and another in Bangkok , Thail and ( n=514 ) . Pregnant women were recruited < 14 weeks gestational age and r and omized to either receive a daily dose of 200 μg I ( as KI ) or an identical placebo throughout pregnancy . Both trials are ongoing , and women are followed up during pregnancy and at delivery . UI , thyroid hormones , and thyroid size are measured . Birth outcomes are recorded , such as gestational age at delivery , height , weight , and APGAR scores , and cord blood and heel stick blood ( < 72 h ) is collected from the child . Child development is assessed at 6 weeks of age using the Neonatal Behavioral Assessment Scale ( NBAS ) , and at 12 and 24 months of age using the Bayley Scales of Infant Development . The outcomes of these trials will contribute importantly to the evidence base for iodine supplementation of pregnant women living in areas of mild iodine deficiency In moderately iodine-deficient , pregnant , thyroid peroxidase antibody (TPO-Ab)-positive women the role of iodine supplementation in the development of postpartum thyroid dysfunction ( PPTD ) was studied in a placebo-controlled , r and omized , double blind trial . Screening for TPO-Ab was performed in early pregnancy in a population of healthy pregnant Danish women with no previous diagnosed thyroid disease ( prevalence , 117 of 1,284 ; 9.1 % ) . The participants were r and omized , stratified according to TPO-Ab level , to three groups . All participants received a daily vitamin and mineral tablet with 150 microg iodine or no iodine . The + /+ group received iodine during pregnancy and the postpartum period , the + /- group received iodine during pregnancy only , and the -/- group received no iodine supplementation . A total of 66 TPO-Ab positive women were followed , and in the postpartum period sera were collected at 8-week interval for biochemical evaluation of thyroid function and antibody level . Compliance was evaluated by 24-h urinary iodine measurements . PPTD developed in 55 % of the participants . In 67 % of the cases abnormal TSH was accompanied by abnormalities in thyroid hormones , whereas 33 % had abnormal serum TSH only . There was no statistically significant difference in the frequency of PPTD in the three groups : + /+ group , 59 % ( 95 % confidence interval , 36 - 79 % ) ; + /- group , 60 % ( 36 - 81 % ) ; and -/- group , 46 % ( 26 - 67 % ) . There were also no differences in the severity of the PPTD , as evaluated by duration and grade of deviation of TSH and thyroid hormones from normality . The occurrence , severity , and type of PPTD predominantly depended on the TPO-Ab level : TPO-Ab below 200 U/L at screening , 35 % developed PPTD ; TPO-Ab of 200 - 900 U/L , 54 % ; and TPO-Ab above 900 U/L , 75 % developed PPTD . Women with low levels of antibodies predominantly remained euthyroid or had hyperthyroidism only , whereas women with high antibody levels had hyperthyroidism followed by hypothyroidism or hypothyroidism only . We conclude that iodine supplementation ( 150 microg ) during pregnancy and the postpartum period to TPO-Ab-positive women living in an area with mild to moderate iodine deficiency did not induce or worsen PPTD . The study confirmed that screening for TPO-Ab in early pregnancy can predict women at high risk for development of PPTD Iodine deficiency control programs have greatly reduced iodine deficiency disorders worldwide . For monitoring changes in iodine status , different indicators may be used . The aim of this study was to evaluate the suitability of indicators of iodine status and thyroid function , thyroglobulin ( Tg ) , thyroid-stimulating hormone ( TSH ) and free thyroxine ( FT4 ) in serum , thyroid volume and urinary iodine concentration , in iodine-deficient schoolchildren under conditions of increasing iodine supply . The study was established as a double-blind , placebo-controlled oral administration of a single dose of iodized oil to schoolchildren ( 7 - 10 y old ) , living in an iodine-deficient area of Benin , with an observation period of 10 mo . However , 3 - 4 mo after supplementation , iodized salt became available in the area . The study population therefore comprised an iodized oil-supplemented group  and a nonsupplemented group  , both of which had variable , uncontrolled intakes of iodized salt during the last 6 mo of the study . Initial mean serum concentrations of TSH and FT4 were within the normal range , whereas serum Tg concentration , urinary iodine concentration and thyroid volume were indicative of moderate-to-severe iodine deficiency . At the end of the study , all indicators had improved significantly , except thyroid volume , which had decreased only in the supplemented group . The supplemented group also still had significantly lower serum Tg and higher urinary iodine concentrations than the nonsupplemented group . Serum Tg and urinary iodine concentrations are the indicators most influenced by a changing iodine supply . Current normal reference ranges of serum concentrations of TSH and FT4 are too wide for detecting iodine deficiency in this age group OBJECTIVE A prospect i ve r and omized trial was performed to assess the usefulness of iodine supplementation in the prevention of goiter in pregnant women living in marginally iodine-deficient areas . DESIGN Eighty-six pregnant women were recruited and r and omized in two groups and treated daily for up to six months after delivery with 200 microg iodide ( group A ) or 50 microg iodide ( group B ) . Sixty-seven women ( 32 in group A and 35 in group B ) completed the study . METHODS Thyroid volume ( TV ) , thyroid functional parameters and urinary iodine concentration were determined in all subjects at booking , at the 18th-26th , and the 29th-33rd week of gestation , and at the 3rd and 6th month after delivery . RESULTS A slight but not significant increase in TV during gestation was observed only in group B. After delivery a progressive decrease in TV was documented in both groups , the final TV being significantly reduced with respect to the initial volume in group A. No significant changes in serum free thyroid hormones and TSH concentrations were found during gestation in either group . Postpartum thyroiditis was observed in 5 women ( 2 in group A , 3 in group B ) . No side effects were seen . CONCLUSION The present data indicate that in marginally iodine-deficient areas , the administration of iodide is recommended in pregnancy and lactation . In the conditions of the present trial a dose of 50 microg iodide/day is a safe and effective measure in preventing an increase in TV during pregnancy but a dose of 200 microg iodide/day appeared to be more effective without inducing side effects and without enhancing the frequency of post-partum thyroiditis Iodine supplementation before pregnancy in iodine-deficient women prevents cretinism and neuromotor deficits in their offspring . It is unclear whether iodine supplementation benefits cognitive function in iodine-deficient school-aged children . We therefore conducted a double-blind , r and omized , controlled trial of the effects of iodized poppy seed oil ( Lipiodol ) on cognitive and motor function and weight gain of iodine-deficient school children . The study was conducted with 305 children in grade s 1 and 2 from 10 primary schools in two iodine-deficient areas in Bangladesh . The children were stratified by school and grade and r and omly assigned to receive 400 mg of oral Lipiodol or a placebo . All children were given a battery of cognitive and motor function tests and had their weights , serum thyroxine ( T4 ) and thyroid-stimulating hormone ( TSH ) and urinary iodine levels measured before and 4 mo after the intervention . On enrollment , both groups were moderately iodine deficient ( median urinary iodine values : placebo group = 3.3 micromol/L , n = 148 ; iodine group = 3.1 micromol/L , n = 152 ; goiter prevalence in both groups > 95 % ) . However , their T4 and TSH levels were within the normal range . After 4 mo , there was a significant treatment effect on urinary iodine levels ( P < 0.0001 ) , but the levels of the treated group were still below normal ( median = 7.9 micromol/L ) . No significant differences were found in T4 and TSH levels , weight gain , cognitive or motor function . The findings suggest that Lipiodol supplementation in moderately iodine-deficient children with normal T4 levels is unlikely to benefit their cognitive function . However , it remains possible that other iodine preparations may have benefits BACKGROUND In developing countries , many children are at high risk of goiter and iron deficiency anemia . Because iron deficiency can have adverse effects on thyroid metabolism , iron deficiency may influence the response to supplemental iodine in areas of endemic goiter . OBJECTIVE The aim of this study was to determine whether goitrous children with iron deficiency anemia would respond to oral iodine supplementation . DESIGN A trial of oral iodine supplementation was carried out in an area of endemic goiter in western Côte d'Ivoire in goitrous children ( n = 109 ) aged 6 - 12 y. Group 1 ( n = 53 ) consisted of goitrous children who were not anemic . Group 2 ( n = 56 ) consisted of goitrous children who had iron deficiency anemia . At baseline , thyroid gl and volume and urinary iodine , thyrotropin , and thyroxine were measured by using ultrasound . Each child received 200 mg I orally and was observed for 30 wk , during which urinary iodine , thyrotropin , thyroxine , hemoglobin , and thyroid gl and volume were measured . RESULTS The prevalence of goiter at 30 wk was 12 % in group 1 and 64 % in group 2 . The mean percentage change from baseline in thyroid volume 30 wk after administration of oral iodine was -45.1 % in group 1 and -21.8 % in group 2 ( P < 0.001 ) . Among the anemic children , there was a strong correlation between the percentage decrease in thyroid volume and hemoglobin concentration ( r(2 ) = 0.65 ) . CONCLUSION The therapeutic response to oral iodine was impaired in goitrous children with iron deficiency anemia , suggesting that the presence of iron deficiency anemia in children limits the effectiveness of iodine intervention programs 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 OBJECTIVE In a previous study in 1983 , goiter was found to be endemic in Shahriar , Iran .  Iodized salt has been distributed in the region for the past 12 years , and the present study was performed to examine the effect of iodide supplementation on indicators of iodine deficiency ( IDD ) and thyroid antibodies . DESIGN & METHODS A total of 3164 people , 58 % women and 42 % men , were selected by r and om sampling from the Shahriar area . Goiter was staged according to World Health Organization guidelines . Urinary iodine was measured by a digestion method , and thyroid hormone measurements were done by radioimmunoassay . The results were compared with those of 1983 . RESULTS Goiter prevalence before and after iodine supplementation was 50 and 40 % in men , 70 and 51 % in women , and 60 and 47 % in the whole community , respectively ( p < 0.001 ) . A decrease in the prevalence of goiter was observed especially in younger individuals . The mean urinary iodine excretion was 7.6 and 18.5 micrograms/dL , before and after iodine supplementation . In 1983 , the urinary iodine in 47.5 % of the population studied was between 2 to 5 micrograms/dL , while in 1995 , 65 % of the population studied had urinary iodine between 10 to 25 micrograms/dL , 12 years after iodine supplementation . Mean serum T4 , T3 , and thyroid-stimulating hormone ( TSH ) were normal before and after intervention . There was no significant change in occurrence of positive antibodies , or of hypo- and hyperthyroidism , following iodine supplementation . CONCLUSION The result of this study shows that the use of iodized salt causes an increase in excreted urinary iodine and a decrease in the prevalence of thyroid goiter , especially in younger age groups . Consumption of iodized salt with 40 parts per million ( ppm ) iodine has not caused increased prevalence of thyroid dysfunction in this area Growth and development of 207 children ( 49 % males ; mean age 5.4 years [ SD 0.2 ] , range 4 to 7.3 years whose mothers received iodine during pregnancy , and children who received iodine first in their 2nd year , were examined in 1996 ; 192 children ( 49 % males ; mean age 6.5 years [ SD 0.2 ] , range 5.8 to 6.9 years ) whose mothers received iodine while pregnant were seen in 1998 . Children were from the southern part of China 's Xinjiang Province which has the lowest levels of iodine in water and soil ever recorded .  Head circumference but not height was improved for those who received iodine during pregnancy ( compared with those receiving iodine at age 2 ) and for those supplemented before the end of the 2nd trimester ( relative to those supplemented during the 3rd trimester ) . Iodine before the 3rd trimester predicted higher psychomotor test scores for children relative to those provided iodine later in pregnancy or at 2 years . Results from the test for cognitive development result ed in trend only differences between those children supplemented during pregnancy versus later . The results address the question of when maternal iodine supplements should begin in public health programs world wide . Findings may be relevant to the treatment of maternal and newborn thyroid deficiency in industrialized countries , particularly for those infants delivered before the end of the second trimester 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 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 BACKGROUND About one billion people worldwide are at risk for iodine deficiency . Despite existing programs of prophylaxis , the prevention of iodine deficiency is still a challenge throughout the developing world . We studied the efficacy of low doses of iodized oil in an area of severe iodine deficiency in Zaire . METHODS Seventy-five subjects with visible goiter were r and omly assigned to receive a single oral dose of placebo or either 0.1 or 0.25 ml of iodized oil , corresponding to 0 , 47 , and 118 mg of iodine , respectively . The mean ages of the subjects in the three groups were 23 , 22 , and 22 years , respectively , and the ratios of males to females were 0.25 , 0.32 , and 0.19 .  Efficacy was assessed by evaluating goiter size and measuring urinary iodine and serum thyroid hormone concentrations for 12 months . RESULTS Goiter size decreased in most of the subjects who received either dose of iodized oil . Their urinary iodine concentrations were normal for six to nine months and their serum thyroxine and thyrotropin concentrations were nearly all normal throughout the study period . There were no side effects , even in subjects whose serum thyroxine concentrations had initially been low . In the placebo group , neither goiter size nor any of the biochemical values changed . CONCLUSIONS The oral administration of a single small dose of iodized oil is capable of correcting iodine deficiency for about a year . This method of supplementation is likely to be more effective , efficient , and acceptable than the administration of either intramuscular or large oral doses of iodized oil Thyroid gl and size was ultrasonographically determined in 35 pregnant women who live in an area with moderate iodine deficiency .  Iodide salt was administered to group A ( n = 17 ) , whereas group B ( n = 18 ) was used as a control . Each group was tested for thyroid-stimulating hormone serum levels , iodine excretion , and thyroid volume . In both groups thyroid-stimulating hormone levels were similar and did not change throughout pregnancy . The iodine excretion at the third trimester in the treated group was significantly ( p less than 0.01 ) higher than that of group B ( 100.0 + /- 39.0 versus 50.0 + /- 37.0 micrograms iodine per 24 hours , respectively ) . Initially , thyroid volume did not differ between the two groups . At the end of pregnancy , no difference was found in thyroid size in group A , whereas in the untreated women it increased significantly ( p less than 0.0001 ) with a mean increase of 1.6 + /- 0.6 ml ( 16.2 % + /- 6.0 % ) . These results show that the increased thyroid size in the control group was mainly a result of relative iodine deficiency and that iodoprophylaxis should be warranted even in areas with moderate iodine deficiency to prevent the increase in thyroid size and , probably , to avoid the risk of maternal and fetal hypothyroidism OBJECTIVE Denmark was an area of iodine deficiency , and m and atory iodine fortification of table salt and salt in bread ( 13 p.p.m . iodine ) was initiated in 2000/2001 . The Danish investigation on iodine intake and thyroid disease ( DanThyr ) is the monitoring of the iodine fortification program . DESIGN AND METHODS DanThyr consists of three main parts : a study of population cohorts initialized before ( n=4649 ) and after ( n=3570 ) iodization of salt  , a prospect i ve identification of incident cases of overt hyper- and hypothyroidism in a population of around 550,000 people since 1997 , and compilation of data from the national registers on the use of thyroid medication , thyroid surgery , and radioiodine therapy . Studies were carried-out in parallel in subcohorts living in areas with differences in iodine content of ground water . RESULTS The study showed profound effects of even small differences in iodine intake level on the prevalence of goiter , nodules , and thyroid dysfunction . Mild and moderate iodine deficiency was associated with a decrease in serum TSH with age . Other environmental factors were also important for goiter development ( increase in risk , smoking and pregnancy ; decrease in risk , oral contraception and alcohol consumption ) , and the individual risk depended on the genetic background . Environmental factors had only a minor influence on the prevalence of thyroid autoantibodies in the population . There were more cases of overt hypothyroidism in mild than in moderate iodine deficiency caused by a 53 % higher incidence of spontaneous ( presumably autoimmune ) hypothyroidism . On the other h and , there were 49 % more cases of overt hyperthyroidism in the area with moderate iodine deficiency . The cautious iodine fortification program , aim ing at an average increase in iodine intake of 50 mug/day has been associated with a 50 % increase in incidence of hyperthyroidism in the area with the most severe iodine deficiency . The incidence is expected to decrease in the future , but there may be more cases of Graves ' hyperthyroidism in young people . CONCLUSION A number of environmental factors influence the epidemiology of thyroid disorders , and even relatively small abnormalities and differences in the level of iodine intake of a population have profound effects on the occurrence of thyroid abnormalities . Monitoring and adjustment of iodine intake in the population is an important part of preventive medicine BACKGROUND The effects of severe iodine deficiency during critical periods of brain development are well documented . There is little known about the consequences of milder forms of iodine deficiency on neurodevelopment . OBJECTIVE The objective was to determine whether supplementing mildly iodine-deficient children with iodine improves cognition . DESIGN A r and omized , placebo-controlled , double-blind trial was conducted in 184 children aged 10 - 13 y in Dunedin , New Zeal and . Children were r and omly assigned to receive a daily tablet containing either 150 microg I or placebo for 28 wk .  Biochemical , anthropometric , and dietary data were collected from each child at baseline and after 28 wk . Cognitive performance was assessed through 4 subtests from the Wechsler Intelligence Scale for Children . RESULTS At baseline , children were mildly iodine deficient [ median urinary iodine concentration ( UIC ) : 63 microg/L ; thyroglobulin concentration : 16.4 microg/L ] . After 28 wk , iodine status improved in the supplemented group ( UIC : 145 microg/L ; thyroglobulin : 8.5 microg/L ) , whereas the placebo group remained iodine deficient ( UIC : 81 microg/L ; thyroglobulin : 11.6 microg/L ) . Iodine supplementation significantly improved scores for 2 of the 4 cognitive subtests [ picture concepts ( P = 0.023 ) and matrix reasoning ( P = 0.040 ) ] but not for letter-number sequencing ( P = 0.480 ) or symbol search ( P = 0.608 ) . The overall cognitive score of the iodine-supplemented group was 0.19 SDs higher than that of the placebo group ( P = 0.011 ) . CONCLUSIONS Iodine supplementation improved perceptual reasoning in mildly iodine-deficient children and suggests that mild iodine deficiency could prevent children from attaining their full intellectual potential . The trial was registered with the Australia New Zeal and Clinical Trials Register as ACTRN12608000222347 BACKGROUND Iodine deficiency in infants can damage the developing brain and increase mortality . Present recommendations state that oral iodised oil should be given to breastfeeding mothers to correct iodine deficiency in infancy when iodised salt is not available , and that direct supplementation should be given to infants who are not being breastfed or receiving iodine-fortified complimentary foods . However , there is little evidence for these recommendations . We aim ed to assess the safety and efficacy of direct versus indirect supplementation of the infant . METHODS We did this double blind , r and omised , placebo-controlled trial in Morocco . Healthy breastfeeding mothers and their term newborn babies ( aged ≤8 weeks ) were block r and omised by clinic day to receive either : one dose of 400 mg iodine to the mother and placebo to the infant ( indirect infant supplementation ) , or one dose of about 100 mg iodine to the infant and placebo to the mother ( direct infant supplementation ) . R and omisation was masked to participants and investigators . Co primary outcomes were : maternal and infant urinary iodine concentrations , breastmilk iodine concentration , maternal and infant thyroid-stimulating hormone ( TSH ) concentrations , maternal and infant thyroxine ( T4 ) concentrations , and infant growth . These outcomes were measured at baseline , and when infants were aged about 3 months , 6 months , and 9 months , and the two groups were compared using mixed effects models . This study is registered with Clinical Trials.gov , number NCT01126125 . FINDINGS We recruited 241 mother-infant pairs between Feb 25 , and Aug 10 , 2010 , and completed data collection by Aug 6 , 2011 . At baseline , median urinary iodine concentration was 35 μg/L ( IQR 29 - 40 ) in mothers and 73 μg/L ( 29 - 237 ) in infants , suggesting iodine deficiency . During the study , maternal urinary iodine concentration ( p=0.011 ) , breastmilk iodine concentration ( p<0.0001 ) , and infant urinary iodine concentration ( p=0.042 ) were higher in the indirect infant supplementation group than in the direct supplementation group . Maternal TSH ( p=0.276 ) and T4 ( p=0.074 ) concentrations did not differ between the groups over the course of the study , nor did infant TSH ( p=0.597 ) and T4 ( p=0.184 ) concentrations , but the number of infants with thyroid hypofunction was lower ( p=0.023 ) in the indirect supplementation group than the direct supplementation group . The infant groups did not differ in anthropomorphic measures , except that length-for-age Z score was slightly greater in the direct infant supplementation group ( p=0.032 ) . At 3 months and 6 months of age , median infant urinary iodine concentration in the indirect infant supplementation group was sufficient ( > 100 μg/L ) , whereas infant urinary iodine concentration was sufficient only at 6 months in the direct supplementation group . There were no serious adverse events in either group . INTERPRETATION In regions of moderate-to-severe iodine deficiency without effective salt iodisation , lactating women who receive one dose of 400 mg iodine as oral iodised oil soon after delivery can provide adequate iodine to their infants through breastmilk for at least 6 months , enabling the infants to achieve euthyroidism . Direct supplementation is less effective in improving infant iodine status . FUNDING ETH Zurich , Switzerl and ; the Medicor Foundation , Vaduz , Lichtenstein Background Concern that mild iodine deficiency in pregnancy may adversely affect neurodevelopment of offspring has led to recommendations for iodine supplementation in the absence of evidence from r and omised controlled trials . The primary objective of the study was to investigate the effect of iodine supplementation during pregnancy on childhood neurodevelopment . Secondary outcomes included pregnancy outcomes , maternal thyroid function and general health . Methods Women with a singleton pregnancy of fewer than 20 weeks were r and omly assigned to iodine ( 150 μg/d ) or placebo from trial entry to birth . Childhood neurodevelopment was assessed at 18 months by using Bayley Scales of Infant and Toddler Development ( Bayley-III ) . Iodine status and thyroid function were assessed at baseline and at 36 weeks ’ gestation . Pregnancy outcomes were collected from medical records . Results The trial was stopped after 59 women were r and omly assigned following withdrawal of support by the funding body . There were no differences in childhood neurodevelopmental scores between the iodine treated and placebo groups . The mean cognitive , language and motor scores on the Bayley-III ( iodine versus placebo , respectively ) were 99.4 ± 12.2 versus 101.7 ± 8.2 ( mean difference ( MD ) −2.3 , 95 % confidence interval ( CI ) −7.8 , 3.2 ; P = 0.42 ) , 97.2 ± 12.2 versus 97.9 ± 11.5 ( MD −0.7 , 95 % CI −7.0 , 5.6 ; P = 0.83 ) and 93.9 ± 10.8 versus 92.4 ± 9.7 ( MD 1.4 , 95 % CI −4.0 , 6.9 ; P = 0.61 ) , respectively . No differences were identified between groups in any secondary outcomes . Conclusions Iodine supplementation in pregnancy did not result in better childhood neurodevelopment in this small trial . Adequately powered r and omised controlled trials are needed to provide conclusive evidence regarding the effect of iodine supplementation in pregnancy . Trials registration The trial was registered with the Australian New Zeal and Clinical Trials Registry at http://www.anzctr.org.au . The registration number of this trial is ACTRN12610000411044 . The trial was registered on 21 May 2010 In Central Africa , all of northern Zaire is very severely deficient in iodine . A peculiar feature of this endemia is that iodine deficiency and the ensuing thyroid gl and stimulation not only leads to goitre formation but also to progressive thyroid involution and to myxoedematous cretinism . An iodine supplementation trial based on oral administration of small doses of iodine was made in 81 schoolchildren . All of them received a small dose of iodine ( 0.1 ml containing 48 mg ) per os and the thyroid status was followed during 4 months . Blood and urine sample s were collected at the start of the study , then 2 weeks , 2 months and 4 months after iodine administration . Before iodine supplementation the mean urinary iodine level was 0.18 + /- 0.02 micromol/l , and 10 % of the subjects had a urinary iodine level below 0.08 micromol/l . Fifty-two percent of the subjects had a serum thyrotropin ( TSH ) level above 10 mU/l . All the subjects responded to the administration of iodine . and all of them recovered a euthyroid status . Most of them were still euthyroid at the end of the study . However . within 4 or even 2 months , some subjects ( 15 % of the total ) reverted to hypothyroidism . At the entry of the study these subjects were all hypothyroid and had elevated TSH and paradoxically low serum thyroglobulin ( TG ) values . In myxoedematous cretins living in the same area , even lower serum TG levels were found . Together with the absence of goitre , a paradoxically low serum TG Suggests a low thyroid reserve , and in the present case a reduced amount of functional thyroid tissue . We show that the serum TG/TSH ratio may be used as a predictive index of thyroid reserve and of positive response to iodine administration . These data further suggest that thyroid damage is not confined to myxoedematous cretins . but is widely distributed in the phenotypically normal population . Widely distributed thyroid damage may render iodine prophylaxis based on oral administration unpredictable 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 Reduced maternal thyroid hormone concentrations during pregnancy can adversely affect fetal neurological development . In the context of national iodine supplementation programmes , concern has been expressed over the theoretical possibility that iodine supplementation during pregnancy might adversely affect fetal development as a result of maternal thyroid inhibition from the Wolff-Chaikoff effect . In a double blind controlled trial in five villages in Papua New Guinea , several measures of motor and cognitive function showed no significant differences at either age 11 or 15 years between those children whose mothers had received supplementary iodine during pregnancy and the control children whose mothers had received the placebo Knowledge of the effect of differences in iodine intake levels on public health in areas with no endemic goiter is limited . Groups at risk when iodine intake is relatively low are pregnant and lactating women and their newborns . A prospect i ve r and omized study was performed to evaluate the effect of iodine supplementation in an area where the median daily iodine excretion in urine is around 50 micrograms . Fifty-four normal pregnant women were r and omized to be controls or to receive 200 micrograms iodine/day from weeks 17 - 18 of pregnancy until 12 months after delivery . In the control group , serum TSH , serum thyroglobulin ( Tg ) , and thyroid size showed significant increases during pregnancy . These variations were ameliorated by iodine supplementation . Iodine did not induce significant variations in serum T4 , T3 , or free T4 . Cord blood Tg was much lower when the mother had received iodine , whereas TSH , T4 , T3 , and free T4 levels were unaltered . The results suggest that a relatively low iodine intake during pregnancy leads to thyroidal stress , with increases in Tg release and thyroid size . However , the thyroid gl and is able to adapt and keep thyroid hormones in the mother and the child normal , at least under normal circumstances , as evaluated in the present study . It is not known whether this stress is sufficient to be of importance for late development of autonomous thyroid growth and function
REVIEW ER 'S CONCLUSIONS Iodine supplementation in a population with high levels of endemic cretinism results in an important reduction in the incidence of the condition with no apparent adverse effects
BACKGROUND Iodine deficiency is the leading preventable cause of intellectual impairment in the world .
Although iodine supplementation is generally considered to be safe , there is a possibility of high doses of iodine suppressing maternal thyroid function .
OBJECTIVES The objective of this review was to assess the effects of iodine supplementation before or during pregnancy in areas of iodine deficiency .