Effect of a mandatory iodization program on thyroid gland volume based on individuals' age, gender, and preceding severity of dietary iodine deficiency: a prospective, population-based study. The Danish investigation on iodine intake and thyroid disease, DanThyr: status and perspectives. The nutritional iodine supply of Belgian neonates is still insufficient The impact of iodine supplementation and bread fortification on urinary iodine concentrations in a mildly iodine deficient population of pregnant women in South Australia Iodine supplementation improves cognition in mildly iodine-deficient children. Mild iodine deficiency is associated with elevated hearing thresholds in children in Benin Postpartum thyroid dysfunction in pregnant thyroid peroxidase antibody-positive women living in an area with mild to moderate iodine deficiency: is iodine supplementation safe? Iodine supplementation in pregnancy and its effect on child cognition. Selenium and iodine supplementation: effect on thyroid function of older New Zealanders. Efficacy and safety of iodine in the postpartum period in an area of mild iodine deficiency. Improved iodine status is associated with improved mental performance of schoolchildren in Benin. Cognitive and motor functions of iodine-deficient but euthyroid children in Bangladesh do not benefit from iodized poppy seed oil (Lipiodol). 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. Vitamin A supplementation in iodine-deficient African children decreases thyrotropin stimulation of the thyroid and reduces the goiter rate. Thyroglobulin as a marker of iodine nutrition status in the general population. Iodine prophylaxis using iodized salt and risk of maternal thyroid failure in conditions of mild iodine deficiency. A cross-sectional survey of urinary iodine status in Latvia. Direct iodine supplementation of infants versus supplementation of their breastfeeding mothers: a double-blind, randomised, placebo-controlled trial.
OBJECTIVE We aim ed to evaluate prospect ively the effect of 4 yr of m and atory iodization of salt ( 13 ppm iodine ) on thyroid volume in two regional areas with respectively mild and moderate iodine deficiency . METHODS Two separate cross-sectional studies were performed before ( n=4649 ) and after ( n=3570 ) the iodization in year 2000 in two areas with mild and moderate iodine deficiency . Women aged 18 - 22 , 25 - 30 , 40 - 45 , and 60 - 65 yr and men aged 60 - 65 yr were examined .  Thyroid ultrasonography was performed . RESULTS A lower median thyroid volume was seen in all age groups after iodization . The largest relative decline was found among the younger females from the area with previous , moderate iodine deficiency . Only a minor decrease was seen among the youngest participants in the area with previous , mild iodine deficiency . After iodization , there were no regional differences in median thyroid volume in the age groups younger than 45 yr . When adjusted for confounders , a lower mean volume was seen among those with multiple nodules in both areas and in the group with diffuse structure in the area with moderate iodine deficiency . Before the iodization , 17.6 % of the total cross-section had thyroid enlargement ; after the iodization , 10.9 % of the cross-section had thyroid enlargement . CONCLUSION In this prospect i ve study , we demonstrated a lower thyroid volume in all age groups after iodization of salt . The decline was largest in the area with former , moderate iodine deficiency . The equal volumes in the regions among the younger age groups indicate approximation to an optimal iodine intake 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 Abstract . Belgium used to be affected by mild iodine deficiency . Improvement in iodine nutrition has been recently documented in schoolchildren in Belgium in spite of the absence of any systematic programme of iodine supplementation . The question arises as to whether this ' silent iodine prophylaxis ' affected also the neonates . A total of 185 r and om urine sample s were collected from 90 full term and 65 preterm neonates in Brussels on day 5 and repeated on day 30 in 30 preterms who were bottle-fed with iodine-enriched formula-milk . The iodine content was also determined in 58 sample s of breast-milk on day 5 . The median urinary iodine on day 5 in full term neonates was 86 µg/l , which is markedly higher than the figure of 48 µg/L reported 15 years previously in neonates in the same area but still much lower than normal for this age group ( 150–200 µg/l ) . The mean iodine content of breast-milk was 78 µg/l , which is unchanged as compared to 15 years ago and is about 66 % of normal . Finally , the median urinary iodine increased from 60 µg/l on day 5 to 150 µg/l on day 30 in preterms bottle-fed with iodine-enriched formula-milk . Conclusion : the status of iodine nutrition has also improved spontaneously in Belgian neonates but has not yet normalised . Lactating and probably pregnant women remain clearly iodine deficient . The iodine-enriched formula-milk for preterms is efficient in correcting their iodine deficiency . National measures are urgently required for correction of iodine deficiency in Belgium Mild iodine deficiency during pregnancy can have significant effects on fetal development and future cognitive function . The purpose of this study was to characterise the iodine status of South Australian women during pregnancy and relate it to the use of iodine-containing multivitamins . The impact of fortification of bread with iodized salt was also assessed . Women ( n = 196 ) were recruited prospect ively at the beginning of pregnancy and urine collected at 12 , 18 , 30 , 36 weeks gestation and 6 months postpartum . The use of a multivitamin supplement was recorded at each visit . Spot urinary iodine concentrations ( UIC ) were assessed . Median UICs were within the mildly deficient range in women not taking supplements ( < 90 μg/L ) . Among the women taking iodine-containing multivitamins  UICs were within WHO recommendations ( 150–249 μg/L ) for sufficiency and showed an increasing trend through gestation . The fortification of bread with iodized salt  increased the median UIC from 68 μg/L to 84 μg/L ( p = .011 ) which was still in the deficient range . Pregnant women in this region of Australia were unlikely to reach recommended iodine levels without an iodine supplement , even after the m and atory iodine supplementation of bread was instituted in October 2009 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 Objective : Elevated hearing thresholds have been demonstrated in population s afflicted by endemic cretinism as a result of severe iodine deficiency . However , data on the effects of less severe iodine deficiency on hearing thresholds in apparently normal children are scant . This study addresses the question whether there is a relationship among iodine variables , hearing and mental performance in a mildly iodine-deficient population . Design : A r and omized , placebo-controlled intervention trial with an observation period of 11 months . Setting : An iodine-deficient area in northern Benin . Subjects : A total of 197 school children , aged 7–11 y. Interventions : A total of 97 children received an oral dose of iodized oil , containing 540 mg I , while 100 children received a placebo . About 3–4 months after supplementation , the whole population began to have access to iodized salt .  Non-verbal mental tests were administered and biochemical indicators ( thyrotropin , free thyroxine , thyroglobulin and urinary iodine ) were measured at the beginning and the end of the study . Hearing was measured at the end of the study in both ears by pure-tone audiometry at seven frequencies . Results : In this mildly iodine-deficient child population children with higher serum thyroglobulin concentrations had significantly higher hearing thresholds in the higher frequency range ( ≥2000 Hz ) than children with lower serum thyroglobulin concentration . Moreover children with lower hearing thresholds performed significantly better on the mental tests used . Conclusions : Even when iodine deficiency is ‘ mild ’ , promotion of adequate iodine intake through salt iodization programs and other means remains crucial . Sponsorship : Nestlé Foundation , Lausanne , Switzerl and ; Wageningen University , Wageningen , The Netherl and s . European Journal of Clinical Nutrition ( 2001 ) 55 , 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 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 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 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 An adequate iodine supply in utero and shortly after birth is known to be crucial to an individual 's physical and mental development . The question of whether iodine supplementation later in life can exert a favorable influence on the mental performance of iodine-deficient population s was addressed in various studies , but with contradictory results . OBJECTIVE The aim of this study was to examine the effect of an improvement in iodine status on mental and psychomotor performance of schoolchildren ( 7 - 11 y ) who were moderately to severely iodine deficient . DESIGN The study , which was originally planned as a double-blind , r and omized , placebo-controlled intervention , was carried out in an iodine-deficient population of schoolchildren ( n = 196 ) in northern Benin . As the population began to have access to iodized salt during the 1-y intervention period , the study population was split post hoc-on the basis of urinary iodine concentrations-into a group with improved iodine status and a group with unchanged iodine status . Changes in mental and psychomotor performance over the intervention period were compared . RESULTS Children with increased urinary iodine concentrations had a significantly greater increase in performance on the combination of mental tests than did the group with no change in urinary iodine concentrations . CONCLUSIONS An improvement in iodine status , rather than iodine status itself , determined mental performance in this population , which was initially iodine deficient . These findings suggest a " catch-up " effect in terms of mental performance 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 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 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 OBJECTIVE The iodine status of a population is traditionally evaluated by either urinary iodine ( UI ) excretion or by some measure of thyroid volume and the prevalence of goitre . In this prospect i ve study of a m and atory iodization programme , we aim ed to evaluate serum thyroglobulin ( Tg ) as a marker of iodine status in the population . METHODS Two identical cross-sectional studies were performed before ( 1997 - 1998 , n=4649 ) and after ( 2004 - 2005 , n=3570 ) the initiation of the Danish iodization programme in two areas with mild and moderate iodine deficiency .  Serum Tg was measured from blood sample s. Thyroid volume was measured by ultrasonography . RESULTS Before iodization , the median serum Tg was considerably higher in moderate than in mild iodine deficiency . Iodization led to a lower serum Tg in all examined age groups . The marked pre-iodization difference in Tg level between the regions was eliminated . The prevalence of Tg above the suggested reference limit ( 40 microg/l ) decreased from 11.3 to 3.7 % ( P<0.0001 ) . Using bootstrapping , we demonstrated a higher efficacy of Tg than of thyroid volume to show a difference between pre- and post-iodization values . CONCLUSION We found serum Tg to be a suitable marker of iodine nutrition status in the population . The results may suggest that the Danish iodization programme has led to a sufficient iodine intake , even if the median UI excretion is still marginally low according to WHO criteria 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 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 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
Controlled trials on infant neurodevelopment were lacking ; gestational iodine supplementation reduced maternal thyroid volume and serum thyroglobulin and in some studies prevented a rise in serum thyroid-stimulating hormone .
Iodine supplementation improves some maternal thyroid indices and may benefit aspects of cognitive function in school-age children , even in marginally iodine-deficient areas .
BACKGROUND Although the detrimental effects of severe iodine deficiency are well recognised , the benefits of correcting mild-to-moderate iodine deficiency are uncertain .
OBJECTIVES We undertook a systematic review of the impact of iodine supplementation in population s with mild-to-moderate iodine deficiency .