title: Development of a dried whole-blood spot thyroglobulin assay and its evaluation as an indicator of thyroid status in goitrous children receiving iodized salt. 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. Efficacy of daily and weekly multiple micronutrient food-like tablets for the correction of iodine deficiency in Indonesian males aged 6-12 mo. Intermittent oral administration of potassium iodide solution for the correction of iodine deficiency. Persistence of goiter despite oral iodine supplementation in goitrous children with iron deficiency anemia in Côte d'Ivoire. Cognitive and motor functions of iodine-deficient but euthyroid children in Bangladesh do not benefit from iodized poppy seed oil (Lipiodol). Iodine supplementation improves cognition in iodine-deficient schoolchildren in Albania: a randomized, controlled, double-blind study. Efficacy and safety of iodine in the postpartum period in an area of mild iodine deficiency. Serum Tg--a sensitive marker of thyroid abnormalities and iodine deficiency in epidemiological studies. Assessment of iodine status using dried blood spot thyroglobulin: development of reference material and establishment of an international reference range in iodine-sufficient children. Comparison of two different doses of iodide in the prevention of gestational goiter in marginal iodine deficiency: a longitudinal study. 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. Efficacy of low oral doses of iodized oil in the control of iodine deficiency in Zaire. Earliest prevention of endemic goiter by iodine supplementation during pregnancy. Iodine supplementation with oral or intramuscular iodized oil. A two-year follow-up of a comparative trial. Randomised trial of iodine intake and thyroid status in preterm infants The effect of varying doses of oral iodized oil in the prophylaxis of endemic goitre in elementary schools children.
abstract: BACKGROUND Serum thyroglobulin appears to be a sensitive marker of thyroid dysfunction in endemic goiter . However , its value as an indicator of thyroid status in children after the introduction of iodized salt  has not been tested . OBJECTIVE The objective was to optimize and vali date a thyroglobulin assay on dried whole blood spots and to evaluate thyroglobulin as an indicator of thyroid response to iodized salt . DESIGN A st and ardized , commercially available , s and wich fluoroimmunometric serum thyroglobulin assay was adapted for use on blood spots and vali date d in Swiss children . In a 1-y prospect i ve study in 377 goitrous Moroccan children aged 6 - 15 y , the assay was used to measure thyroglobulin before and after the introduction of iodized salt .  Urinary iodine , thyroid volume , thyrotropin , and thyroxine were measured , and regression was done with thyroglobulin as the dependent variable . RESULTS Correlation between the blood spot and serum assays was excellent ( r = 0.98 ) . The SD of the difference between the blood spot and serum assays was 3.8 micro g/L ; the median CVs for the blood spot assay in controls and sample s were 6.3 % and 14.4 % , respectively . Median thyroglobulin was 24.5 ( range : 0 - 328.8 ) micro g/L at baseline and fell significantly after the introduction of iodized salt to 6.2 ( 0 - 83.1 ) and 4.4 ( 0 - 47.1 ) micro g/L at 5 and 12 mo , respectively ( P < 0.0001 ) . Regression of urinary iodine and thyroid volume on thyroglobulin was highly significant at baseline and at 5 mo ( P < 0.001 ) . CONCLUSION Thyroglobulin , measured in dried whole blood spots , may be a valuable indicator of improving thyroid function in children after supplementation with iodized salt 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 Infants are highly vulnerable to iodine deficiency , and little data exist on the effect of multiple micronutrient supplementation on their iodine status . OBJECTIVE We aim ed to compare the efficacy of daily and weekly multiple micronutrient food-like tablets ( foodLETs ) on increasing iodine status among infants . DESIGN In a double-blind , placebo-controlled trial , 133 Indonesian males aged 6 - 12 mo were r and omly assigned to 1 of 4 groups : a daily multiple-micronutrient foodLET providing the Recommended Nutrient Intake (RNI)(DMM ) , a weekly multiple-micronutrient foodLET providing twice the RNI ( WMM ) , a daily 10-mg Fe foodLET ( DI ) , or placebo .  Urinary iodine ( UI ) concentrations were measured at baseline and at 23 wk . RESULTS At baseline , the average UI concentration ( 1.37 micromol/L ) was within the normal range , and 30.8 % of subjects had iodine deficiency ( UI < 0.79 micromol/L ) . At 23 wk , the DMM group had the highest increment in UI ; however , after adjustment for initial UI , the changes in UI were not significantly different between the 4 groups ( P = 0.39 ) . Initial UI correlated inversely with the changes in UI ( P < 0.001 ) . The DMM group had the greatest reduction and increment in the proportion of iodine-deficient infants and in infants with iodine excess , respectively ; however , no significant difference was found in these proportions ( P = 0.13 and P = 0.42 ) between the 4 groups . CONCLUSION Daily consumption of a multiple-micronutrient foodLET providing the RNI during infancy may be one strategy to improve iodine status Iodized salt and iodized oil are the main methods used to prevent iodine deficiency , but sometimes alternative approaches are needed . We tested the efficacy of various regimens for the intermittent administration of potassium iodide in Hwedza , Zimbabwe , an area of known severe iodine deficiency . We divided 304 schoolchildren aged 7 - 13 y into five equal groups that received iodine as a 10 % solution of potassium iodide as follows : 8.7 mg every 2 wk ( group A ) , 29.7 mg every month ( group B ) , 148.2 mg every 3 mo ( group C ) , 382 mg every 6 mo ( group D ) , or 993 mg once ( group E ) . The follow-up period was 13 mo . No adverse effects were encountered with any of these doses . After 6 mo , the median blood spot thyroglobulin concentration had decreased in all groups and had normalized in groups A and B to values found in iodine-sufficient population s. The number of children with elevated thyroid-stimulating hormone concentrations decreased in groups A-C , but the changes were not significant . Urine iodine concentration generally remained low in all groups but increased in group A. After 13 mo , mean thyroid volume measured by ultrasound had decreased in groups A and B to values comparable with those in iodine-sufficient areas , and was unchanged in the other groups . We conclude that oral potassium iodide is effective for the prophylaxis of iodine deficiency if given as a dose of 30 mg I monthly or 8 mg biweekly 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 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 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 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 Serum Tg is widely used in the control of thyroid cancer but also in the diagnosis of certain other thyroid diseases . Serum Tg may be useful in the characterization of the iodine status of a population , but little is known about determinants of serum Tg levels . We examined a r and om selection of 4,649 subjects from 2 regions in Denmark with different iodine status . Thyroid volume and structure were determined with ultrasonography , and thyroid function tests and Tg analysis were performed . The factor with the closest association with serum Tg levels was thyroid volume at ultrasonography ( P < 0.001 ) . Also thyroid nodularity ( P < 0.001 ) and iodine excretion ( P < 0.001 ) had close associations to serum Tg , even after adjusting for the influence of the other parameters . Thyroid dysfunction had a less pronounced but still highly significant association with serum Tg ( P < 0.001 ) , but no relation was found to serum TSH in general . The association with age seemed to rely on differences in the prevalence of thyroid abnormalities , and men had lower Tg levels than women of the same age . There was a marked difference in serum Tg between the two regions with slightly different iodine excretion also after adjusting for the other factors . In conclusion , serum Tg reflects thyroid abnormalities and thyroid function and is a sensitive marker of iodine deficiency in a population CONTEXT Thyroglobulin ( Tg ) may be a valuable indicator of improving thyroid function in children after salt iodization . A recently developed Tg assay for use on dried whole blood spots ( DBS ) makes sampling practical , even in remote areas . OBJECTIVE The study aim was to develop a reference st and ard for DBS-Tg , establish an international reference range for DBS-Tg in iodine-sufficient children , and test the st and ardized DBS-Tg assay in an intervention trial . DESIGN , PARTICIPANTS , AND INTERVENTIONS Serum Tg reference material of the European Community Bureau of Reference ( CRM-457 ) was adapted for DBS and its stability tested over 1 yr . DBS-Tg was determined in an international sample of 5- to 14-yr-old children ( n = 700 ) who were euthyroid , anti-Tg antibody negative , and residing in areas of long-term iodine sufficiency . In a 10-month trial in iodine-deficient children , DBS-Tg and other indicators of iodine status were measured before and after introduction of iodized salt . RESULTS Stability of the CRM-457 Tg reference st and ard on DBS over 1 yr of storage at -20 and -50 C was acceptable . In the international sample of children , the third and 97th percentiles of DBS-Tg were 4 and 40 microg/liter , respectively . In the intervention , before introduction of iodized salt , median DBS-Tg was 49 microg/liter , and more than two thirds of children had DBS-Tg values greater than 40 microg/liter . After 5 and 10 months of iodized salt use , median DBS-Tg decreased to 13 and 8 microg/liter , respectively , and only 7 and 3 % of children , respectively , had values greater than 40 microg/liter . DBS-Tg correlated well at baseline and 5 months with urinary iodine and thyroid volume . CONCLUSIONS The availability of reference material and an international reference range facilitates the use of DBS-Tg for monitoring of iodine nutrition in school-age children 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 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 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 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 A controlled trial of iodine supplementation comparing oral with intramuscular iodized oil has been carried out in an iodine deficient area of Zaire . Two years after the administration of 2 ml of oral iodized oil to the population of four villages the overall goitre prevalence had fallen from 64 to 54 % . In a further two villages given 2 ml of intramuscular oil the prevalence fell from 65 to 50 % . The effectiveness of supplementation was also assessed by measuring changes in thyroid function in women of reproductive age . Among women in the villages given oral iodized oil , the geometric mean thyroxine concentration , measured in dried bloodspots , rose from 27.2 to 52.6 nmol/L at the two-year follow-up . This was similar to the response of the intramuscularly treated villages in which thyroxine levels rose from 32.1 to 65.4 nmol/L. There was no change in goitre prevalence or thyroid function in two control villages . Oral iodized oil is a cheaper and simpler alternative to the injected form providing effective iodine prophylaxis for up to two years after a single dose BACKGROUND Low levels of circulating thyroid hormones have been associated with poorer general and neurodevelopmental outcome in preterm babies and it has been speculated that the association is causal . Low levels of circulating thyroid hormone have been reported after inadequate intake of iodine in preterm infants being fed milk formula . AIM To investigate whether increased iodine intake from supplemented preterm formula would improve thyroid hormone levels in preterm babies ( this study ) and hence improve neurodevelopmental status ( planned subsequent study ) . METHOD A total of 121 preterm infants were entered into a r and omised controlled trial of st and ard ( 68 μg/l ) versus increased ( 272 μg/l ) iodine in preterm formula . RESULTS The two groups were comparable at recruitment . No evidence of an effect of the intervention on thyroid hormone levels was seen up to 41 weeks after conception . CONCLUSION Calls for increased iodine content of preterm infant formulas are not justified by this study . Key message Increasing milk iodine content in line with the latest recommendations for preterm babies had no effect on thyroid hormone levels in the perinatal The effect of oral iodine supplementation on total goitre rate ( % TGR ) and urinary iodine excretion among school children 4 to 16 years of age was studied . In the first group ( n = 57 ) 200 mg oral iodized oil reduced % TGR from 31.6 % to 17.5 % and 33.3 % to 24.6 % in males and females respectively , while in the second group ( n = 53 ) , 400 mg iodine reduced the % TGR from 34.0 % to 20.8 % in males and 35.9 % to 24.5 % in females after 13 months of intervention . This gave a relative indication that the 200 mg is as effective as the 400 mg in goitre reduction . In subsequent tests , the maximum urinary iodine excretion was obtained from the groups which received two doses of iodized oil 24 hours after the intervention . A significant ( p = 0.003 ) greater increase in urinary iodine excretion was noted at 24 hours among both male and female children administered 400 mg than among those who received 200 mg . Measurements after 24 hours showed no significant difference between urinary iodine excretion of the two dose groups . These results suggest that : ( i ) 200 mg is likely equally effective as 400 mg for iodine deficiency disorders control and prevention among children and ( ii ) iodine could be administered annually rather than biannually
target: Despite the high risk of bias of many of the included studies , the results suggested that urinary iodine , thyroglobin , serum thyroxine , and thyroid-stimulating hormone are useful biomarkers of iodine status , at least in some groups .
background: BACKGROUND Biomarkers of iodine status are required to study iodine deficiency disorders in different parts of the world and to evaluate the effects of fortification strategies .
  OBJECTIVE The objective was to assess the usefulness of biomarkers of iodine status in humans by systematic ally review ing intervention studies that altered iodine status .