Effects of iodine supplementation during pregnancy on child growth and development at school age. Improved iodine status is associated with improved mental performance of schoolchildren in Benin. Iodine supplementation improves cognition in mildly iodine-deficient children. Infant neurocognitive development is independent of the use of iodised salt or iodine supplements given during pregnancy. Iodine supplementation in pregnancy and its effect on child cognition. The effects of oral iodized oil on intelligence, thyroid status, and somatic growth in school-age children from an area of endemic goiter. Iodine supplementation improves cognition in iodine-deficient schoolchildren in Albania: a randomized, controlled, double-blind study. Randomized clinical trial comparing different iodine interventions in school children. Attention deficit and hyperactivity disorders in the offspring of mothers exposed to mild-moderate iodine deficiency: a possible novel iodine deficiency disorder in developed countries. Treatment of iodine deficiency in school-age children increases insulin-like growth factor (IGF)-I and IGF binding protein-3 concentrations and improves somatic growth. The effect of iodine supplementation in pregnancy on early childhood neurodevelopment and clinical outcomes: results of an aborted randomised placebo-controlled trial Psychophysiologic aftereffects of prenatal irradiation. 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. Direct iodine supplementation of infants versus supplementation of their breastfeeding mothers: a double-blind, randomised, placebo-controlled trial. Iodine status as determined by urinary iodine excretion in Lesotho two years after introducing legislation on universal salt iodization. The effect of iron deficiency and mental stimulation on Indonesian children's cognitive performance and development. The Relationship Between Iron Status and Thyroid Hormones in Adolescents Living in an Iodine Deficient 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 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 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 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 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 One hundred goitrous school children received 475 mg iodized oil by mouth , while 100 controls received mineral oil , on a double-blind basis . On follow-up 22 months later the urinary iodine had increased and goiter size had decreased in both groups , more strikingly in the iodine-treated children . There were no consistent differences between the two treatment groups in rate of somatic growth or performance on the Stanford-Binet and Bender tests . Because of the complexities introduced by increases in urinary iodine in the controls , we compared goiter reduction with improvement in IQ score in all children , regardless of group , and found a significant relationship ( p = 0.014 ) , particularly in girls ( p = 0.029 ) . We conclude that oral iodized oil is an attractive alternative to its injection but we recommend an approximate doubling of the dose used here for more effective control . Also , while our data are not conclusive , they support the possibility that correction of iodine deficiency may improve mental performance in school age children , particularly girls BACKGROUND Iodine is required for the production of thyroid hormones , which are necessary for normal brain development and cognition . Although several r and omized trials examined the effect of iodine supplementation on cognitive performance in schoolchildren , the results were equivocal . OBJECTIVE We aim ed to ascertain whether providing iodized oil to iodine-deficient children would affect their cognitive and motor performance . DESIGN In a double-blind intervention trial , 10 - 12-y-old children ( n = 310 ) in primary schools in rural southeastern Albania were r and omly assigned to receive 400 mg I ( as oral iodized oil ) or placebo . We measured urinary iodine ( UI ) , thyroid-stimulating hormone ( TSH ) , and total thyroxine ( TT4 ) concentrations and thyroid gl and volume ( by ultrasound ) . The children were given a battery of 7 cognitive and motor tests , which included measures of information processing , working memory , visual problem solving , visual search , and fine motor skills .  Thyroid ultrasound and the biochemical and psychological tests were repeated after 24 wk . RESULTS At baseline , the children 's median UI concentration was 43 microg/L ; 87 % were goitrous , and nearly one-third had low concentrations of circulating TT4 . Treatment with iodine markedly improved iodine and thyroid status : at 24 wk , median UI in the treated group was 172 microg/L , mean TT4 was approximately 40 % higher , and the prevalence of hypothyroxinemia was < 1 % . In the placebo group after the intervention , these variables did not differ significantly from baseline . Compared with placebo , iodine treatment significantly improved performance on 4 of 7 tests : rapid target marking , symbol search , rapid object naming , and Raven 's Coloured Progressive Matrices ( P < 0.0001 ) . CONCLUSION Information processing , fine motor skills , and visual problem solving are improved by iodine repletion in moderately iodine-deficient schoolchildren OBJECTIVE The purpose of this trial was to compare three different iodine interventions . DESIGN School children aged 8 - 10 years were r and omized into one of three groups : group A was provided with iodized salt by research ers with an iodine concentration of 25 ppm ; group B purchased iodized salt from the market ; and group C was similar to group B with the exception that they were given iodized oil capsules containing 400 mg iodine at the beginning of the study . Salt iodine content was measured bimonthly for 18 months and indicators of iodine deficiency were measured at baseline and 6 , 9 , 12 and 18 months after r and omization . RESULTS The prevalence of abnormal thyroid volumes , based on the World Health Organization ( WHO ) body surface area reference > 97th percentile , was 18 % at baseline and declined to less than 5 % by 12 months in groups A and C , and to 9 % after 18 months in group B. Results for goitre by palpation were similar . The median urinary iodine was 94 microg l(-1 ) at baseline and increased in all groups to > 200 microg l(-1 ) at the 6-month follow-up . CONCLUSIONS In this population of school children with initially a low to moderate level of iodine deficiency , the group receiving salt with 25 ppm ( group A ) was not iodine deficient on all indicators after 18 months of study . When the iodine content of the salt varied , such as in group B , by 18 months thyroid sizes had not yet achieved normal status Over a period of almost 10 yr , we carried out a prospect i ve study of the neuropsychological development of the offspring of 16 women from a moderately iodine-deficient area ( area A ) and of 11 control women from a marginally iodine-sufficient area ( area B ) whose thyroid function had been monitored during early gestation .  Attention deficit and hyperactivity disorder ( ADHD ) was diagnosed in 11 of 16 area A children ( 68.7 % ) but in none from area B. Total intelligence quotient score was lower in area A than in area B children ( 92.1 + /- 7.8 vs. 110 + /- 10 ) and in ADHD children when compared with both non-ADHD children from the same area and control children ( 88.0 + /- 6.9 vs. 99.0 + /- 2.0 and 110 + /- 10 , respectively ) . Seven of 11 ADHD children ( 63.6 % ) were born to the seven of eight area A mothers who became hypothyroxinemic at early gestation , whereas only one of five non-ADHD children was born to a woman who was hypothyroxinemic at 20 wk of gestation . So far , a similar prevalence of ADHD has been reported only in children with generalized resistance to thyroid hormones . This might suggest a common ADHD pathogenetic mechanism consisting either of reduced sensitivity of the nuclear receptors to thyroid hormone ( generalized resistance to thyroid hormones ) or reduced availability of intracellular T3 for nuclear receptor binding . The latter would be the ultimate consequence of maternal hypothyroxinemia ( due to iodine deficiency ) , result ing in a critical reduction of the source of the intracellular T3 available to the developing fetal brain CONTEXT Iodine deficiency in utero impairs fetal growth , but the relationship between iodine deficiency and postnatal growth is less clear . OBJECTIVE The objective of the study was to determine whether iodine repletion improves somatic growth in iodine-deficient children and investigate the role of IGF-I and IGF binding protein (IGFBP)-3 in this effect . DESIGN , PARTICIPANTS , AND INTERVENTIONS Three prospect i ve , double-blind intervention studies were done : 1 ) in a 10-month study , severely iodine-deficient , 7- to 10-yr-old Moroccan children ( n = 71 ) were provided iodized salt and compared with children not using iodized salt ; 2 ) in a 6-month study , moderately iodine-deficient , 10- to 12-yr-old Albanian children ( n = 310 ) were given 400 mg iodine as oral iodized oil or placebo ; 3 ) in a 6-month study , mildly iodine-deficient 5- to 14-yr-old South African children ( n = 188 ) were given two doses of 200 mg iodine as oral iodized oil or placebo . At baseline and follow-up , height , weight , urinary iodine ( UI ) , total T4 ( TT4 ) , TSH , and IGF-I were measured ; in Albania and South Africa , IGFBP-3 was also measured . RESULTS In all three studies , iodine treatment increased median UI to more than 100 microg/liter , whereas median UI in the controls remained unchanged . In South Africa , iodine repletion modestly increased IGF-I but did not have a significant effect on IGFBP-3 , TT4 , or growth . In Albania and Morocco , iodine repletion significantly increased TT4 , IGF-I , IGFBP-3 , weight-for-age z scores , and height-for-age z scores . CONCLUSION This is the first controlled study to clearly demonstrate that iodine repletion in school-age children increases IGF-I and IGFBP-3 concentrations and improves somatic growth 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 Prenatally  irradiated children ( n = 544 ) , who were born between 26 April 1986 and 26 February 1987 , in regions of the Ukraine which were radioactively contaminated as a result of the Chernobyl disaster , their mothers and teachers have been examined with psychometric tests .  The control group of relevant children ( n = 759 ) , their mothers and teachers , were living at the radioecological ' clear ' regions ( Kharkov and Kharkov Region ) . Further , we r and omly selected 50 prenatally irradiated children whose mothers were evacuated from the Chernobyl exclusion zone and 50 age- and -gender-matched non-exposed children . At this phase clinical examinations ,  psychometric tests , computerized EEG , thyroid function assessment and dosimetric reconstruction  were used . We found a significant increase in mental retardation ( IQ < 70 ) and of borderline and low range IQ , as well as emotional and behavioral disorders and a decrease in high IQ ( IQ > 110 ) in children irradiated in utero as a result of the Chernobyl disaster , in comparison with the controls . One important biological mechanism in the genesis of mental disorders in prenatally irradiated children is the radiation-induced malfunction of the thyroid-pituitary system with the effect threshold of 0.30 Sv of thyroid exposure dose . We hypothesize that the cerebral basis of mental disorders in the prenatally irradiated children is the malfunction of the left hemisphere limbic-reticular structures , particularly in those exposed at the most critical period of cerebrogenesis ( 8 - 25 weeks of gestation ) . The data obtained reveal mental disorders in prenatally irradiated children and obviously reflect developmental abnormalities of brain structure and function as a result of the interaction of prenatal and post-natal factors where it is possible to assume radiation effects on the developing brain . A follow-up study of the children irradiated in utero , who may be at risk for schizophrenia , is proposed because of its particular importance to clinical medicine and neuroscience 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 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 OBJECTIVE Mild to severe iodine deficiency has been documented in Lesotho since 1960 . To eliminate the persisting iodine deficiency , legislation on universal salt iodization was introduced in 2000 as a long-term public health intervention strategy . We assessed the urinary iodine status of school children and women of child-bearing age in Lesotho 2 y after the introduction of legislation on universal salt iodization . METHODS A 31-cluster national survey was conducted in 2002 by using the proportion to population size method . In each cluster , 30 women ages 15 to 30 y and 30 primary school children ages 8 to 12 y were r and omly selected to provide urine sample s for urinary iodine analysis . Data were interpreted according to criteria of the World Health Organization , United Nations Children 's Fund , and International Council for Control of Iodine Deficiency Disorders ( 2001 ) . Statistical analysis was performed using SAS . RESULTS We analyzed 912 urine sample s from children and 924 from women . The median urinary iodine concentrations were 214.7 microg/L for children and 280.1 microg/L for women , indicating more than adequate iodine intake . Median iodine concentration was higher in the lowl and s ( 256.0 microg/L in children and 329.9 microg/L in women ) than in the mountains ( 99.30 microg/L in children and 182.6 microg/L in women ) . Analysis of the distribution of the data showed values below 50 microg/L in 10.1 % of children and in 9.8 % of women . In addition , 21.5 % of children and 17.9 % of women had urinary iodine excretion values below 100 microg/L. In contrast , 36 % of children and 47.2 % of women had urinary iodine concentrations in excess of 300 microg/L. CONCLUSION Results of urinary iodine excretion measurements indicated that iodine deficiency has been eliminated as a public health problem in Lesotho . However , the high median urinary iodine concentration of women in the lowl and s indicated the possibility of a risk of iodine-induced hyperthyroidism in vulnerable people Three studies conducted in Indonesia will be described . Soewondo ( 12 ) investigated the relation of iron deficiency and cognitive function and impact of iron supplementation on verbal intelligence , attention and concept learning among iron deficient children without anemia and iron deficient anemic children . Half of 176 children , aged 3 - 6 years , received elemental Fe for 8 weeks and the other half received  placebo . There were significant changes from pre to post intervention evaluations in ferritin , transferrin saturation , free erythrocyte protoporphyrin , and hemoglobin in the iron deficient anemic children . Pre and post treatment psychological test data showed that iron deficiency anemia produced alterations in cognitive processes related to visual attention and concept acquisition . These alterations can be reversed with iron treatment . Idjradinata ( 4 ) assessed the impact of iron supplementation on iron deficient infant 's mental and psychomotor development . Hundred twenty six subjects aged 12 to 18 month were r and omly assigned to either iron treatment or placebo intervention . After 4 months of iron supplementation , the hemoglobin , ferritin and transferrin saturation changed significantly in the iron deficient infants . A developmental delay was observed in the iron deficient anemic infants before intervention and the conditions were reversed after 4 months of iron treatment . Soemiarti ( 8) examined the effectiveness of a  training course  given to mothers of children aged 12 to 24 month on the rearing environment and consequently to the child 's development .  The subjects were 69 mothers of 20 - 35 years old . The training lasted for 21 days by giving mothers training using the program " Ibu Maju Anak Bermutu " . The rearing environment improved , also the child 's mental and psychomotor development BACKGROUND Iron may be only one of many nutritional factors that influence thyroid hormone metabolism in iodine-deficient areas . OBJECTIVE To evaluate the effect of iron status on thyroid hormone profile in adolescents living in a mild iodine-deficient area in Turkey . SUBJECTS Three hundred and thirty school-aged children with mean age 14 years were examined . METHODS Free triiodothyronine , free tetraiodothyronine and thyrotropin levels were analyzed by chemiluminescent enzyme immunoassay .  Hemoglobin and mean corpuscular volume were measured with a Hemocounter . Iron and total iron binding capacity concentration were determined by colorimetric photometric methods . Ferritin level was determined by immunoturbidimetry . RESULTS Thyroid hormone levels of the children with anemia were not significantly different compared to children without anemia . No significant correlation was found between thyroid hormones and iron status . CONCLUSION The thyroid hormone profile was not significantly affected in this area . This survey showed no correlation between iron status and thyroid hormone levels
Thus , regardless of study design , iodine deficiency had a substantial impact on mental development .
Several review s and meta-analyses have examined the effects of iodine on mental development .
None focused on young children , so they were incomplete in summarizing the effects on this important age group .
The current systematic review therefore examined the relationship between iodine and mental development of children 5 years old and under .