The impact of maternal and fetal The impact of maternal and fetal thyroid horome deficiency: thyroid horome deficiency: iodine deficiency disordersiodine deficiency disorders

Professor Steven C. BoyagesProfessor Steven C. BoyagesWestmead HospitalWestmead HospitalSydney, AustraliaSydney, Australia

Iodine Related Thyroid DiseaseIodine Related Thyroid DiseaseSIGNIFICANCESIGNIFICANCE

One of the commonest nutritional disordersOne of the commonest nutritional disorders Over 1 billion people live in deficient Over 1 billion people live in deficient

environmentsenvironments Affects primarily the thyroid but secondarily Affects primarily the thyroid but secondarily

may impact on brain developmentmay impact on brain development Most preventable cause of mental Most preventable cause of mental disabilitydisability Not limited to developing countriesNot limited to developing countries Principles of food fortification to populationsPrinciples of food fortification to populations Structural basis of scientific thinking (Kuhn)Structural basis of scientific thinking (Kuhn)

OutlineOutline Nutritional DisordersNutritional Disorders Principles of thyroid physiologyPrinciples of thyroid physiology Iodine physiologyIodine physiology What is a normal iodine level?What is a normal iodine level? How do we adapt to iodine deficiency?How do we adapt to iodine deficiency? Iodine Deficiency DisordersIodine Deficiency Disorders Are we at risk?Are we at risk? Iodine ExcessIodine Excess Prevention and Food FortificationPrevention and Food Fortification

Nutrition Related DisordersNutrition Related Disorders

MicronutritionMicronutritionUndernutrition PCMUndernutrition PCM

Minerals and VitaminsMinerals and VitaminsFolic AcidFolic Acid

Vitamin D deficiencyVitamin D deficiencyVitamin A deficiencyVitamin A deficiency

Fe deficiencyFe deficiencySelenium deficiencySelenium deficiency

Iodine deficiencyIodine deficiency

MacronutritionMacronutritionObesityObesity

HyperlipidemiaHyperlipidemiaInsulin ResistanceInsulin Resistance

DiabetesDiabetesAlcoholAlcohol

Thyroid PhysiololgyThyroid Physiololgy

Differential expression of TH Differential expression of TH receptorsreceptors

Thyroid Function TestsThyroid Function Tests TSH, direct measure of thyroid TSH, direct measure of thyroid

hormone actionhormone action– Different types of thyroid hormone Different types of thyroid hormone

receptorsreceptors Free T4, estimatesFree T4, estimates Free T3, estimatesFree T3, estimates

Iodine is essential for normal Iodine is essential for normal thyroid hormone synthesisthyroid hormone synthesis

Na Iodide TransporterNa Iodide Transporter

Na Iodide Symporter Na Iodide Symporter distributiondistribution

Altorjay et al. BMC Cancer 2007 7:5   doi:10.1186/1471-2407-7-5

OutlineOutline Nutritional DisordersNutritional Disorders Principles of thyroid physiologyPrinciples of thyroid physiology Iodine physiologyIodine physiology What is a normal iodine level?What is a normal iodine level? How do we adapt to iodine deficiency?How do we adapt to iodine deficiency? Iodine Deficiency DisordersIodine Deficiency Disorders Are we at risk?Are we at risk? Iodine ExcessIodine Excess Prevention and Food FortificationPrevention and Food Fortification

What is normal intake?What is normal intake?Too little and Too much can be Too little and Too much can be

a problema problem

Recommended intakesRecommended intakes

The American Thyroid Association has recently recommended that all women receive 150 µg iodine supplements above their dietary intake during pregnancy and lactation, and that the iodine content in all prenatal vitamins should be standardized at 150 µg

Sources of iodineSources of iodine SaltSalt MilkMilk BreadBread Other foods, eg kelp, seaweed, laverOther foods, eg kelp, seaweed, laver MedicationsMedications

Sources of iodineSources of iodine Dietary iodine Daily intake (µg)Dietary iodine Daily intake (µg) Dairy products Dairy products 5252 GrainsGrains 7878 Meat Meat 3131 Mixed dishes Mixed dishes 2626 Vegetables Vegetables 2020 Desserts Desserts 2020 Eggs Eggs 1010 Iodized salt Iodized salt 380380 Other iodine sourcesOther iodine sources(µg)(µg) Vitamin/mineral prep (per tablet) Vitamin/mineral prep (per tablet) 150150 Amiodarone (per tablet) Amiodarone (per tablet) 75,00075,000 Povidone iodine (per mL) Povidone iodine (per mL) 10,00010,000 Ipodate (per capsule) Ipodate (per capsule) 308,000308,000

OutlineOutline Nutritional DisordersNutritional Disorders Principles of thyroid physiologyPrinciples of thyroid physiology Iodine physiologyIodine physiology What is a normal iodine level?What is a normal iodine level? How do we adapt to iodine deficiency?How do we adapt to iodine deficiency? Iodine Deficiency DisordersIodine Deficiency Disorders Are we at risk?Are we at risk? Iodine ExcessIodine Excess Prevention and Food FortificationPrevention and Food Fortification

Adaptation to iodine deficiencyAdaptation to iodine deficiency

Iodine Deficiency DisordersIodine Deficiency Disorders

Endemic GoitreEndemic Goitre

Adaptation to iodine deficiencyAdaptation to iodine deficiency When iodine supply is low, adequate secretion of thyroid

hormones is achieved by modifications of thyroid activity

The principal regulator of these adaptive processes is TSH and the morphological consequences of prolonged TSH stimulation is the development of goiter

The thyroid adaptive processes fall into two broad areas; augmentation of iodide trapping and subsequent steps of intrathyroidal iodine metabolism and second, the preferential synthesis and secretion of T3.

Augmentation of iodide trapping is the fundamental mechanism by which the thyroid adapts to an insufficient iodine supply and is achieved by autoregulation as well as by TSH stimulation.

Pathogenesis of goitrePathogenesis of goitre

OutlineOutline Nutritional DisordersNutritional Disorders Principles of thyroid physiologyPrinciples of thyroid physiology Iodine physiologyIodine physiology What is a normal iodine level?What is a normal iodine level? How do we adapt to iodine deficiency?How do we adapt to iodine deficiency? Iodine Deficiency DisordersIodine Deficiency Disorders

– Iodine and brain damageIodine and brain damage Are we at risk?Are we at risk? Iodine ExcessIodine Excess Prevention and Food FortificationPrevention and Food Fortification

GEOGRAPHICAL GEOGRAPHICAL CLUSTERINGCLUSTERING

Iodine Deficiency DisordersIodine Deficiency Disorders ThyroidThyroid

– Thyroid autonomyThyroid autonomy– Nodular thyroid Nodular thyroid

diseasedisease– GoitreGoitre– Thyroid MalignancyThyroid Malignancy

BrainBrain– Endemic cretinismEndemic cretinism– DeafnessDeafness– Subclinical deafnessSubclinical deafness– intellectual intellectual

disabilitydisability– ?Attention deficits?Attention deficits– ? Colour perception ? Colour perception

deficitsdeficitsIodine Deficiency Disorders (IDD)Iodine Deficiency Disorders (IDD)

1000 million people at risk for 1000 million people at risk for the development of IDDthe development of IDD

Iodine Deficiency DisordersIodine Deficiency Disorders Iodine Deficiency Disorders (IDD) refers to

all of the ill effects of iodine deficiency in a population that can be prevented by ensuring that the population has an adequate intake of iodine

Iodine deficiency at critical stages during pregnancy and early childhood results in impaired development of the brain and consequently in impaired mental function.

Timing of insultTiming of insultTiming of Timing of

insultinsultPrenatalPrenatal PostnatalPostnatal

TargetTarget Fetal brainFetal brainFetal thyroidFetal thyroid

Maternal Maternal thyroidthyroid

Child and Child and AdultAdult

ThyroidThyroid

OutcomeOutcome Endemic Endemic cretinismcretinism

Impaired IQImpaired IQ

Endemic Endemic GoitreGoitreShort Short

StatureStature

Early recognition of goitre with Early recognition of goitre with impaired mental abilityimpaired mental ability

"Hence while travelling in a "Hence while travelling in a certain region in the County certain region in the County Tyrol, under the jurisdiction of Tyrol, under the jurisdiction of the Bishop of Gurk, I was the Bishop of Gurk, I was astonished at the very large astonished at the very large number of number of madmen, fools and madmen, fools and doltsdolts; but when I considered ; but when I considered the frigidity and the humidity the frigidity and the humidity of the air, and also perceived of the air, and also perceived the crudity of the waters from the crudity of the waters from the very frequent occurrence the very frequent occurrence of of goitregoitre... all astonishment ... all astonishment ceased entirely." ceased entirely."

EUSTACHIUS RUDIUS, A EUSTACHIUS RUDIUS, A PHYSICIAN FROM UTRECHTPHYSICIAN FROM UTRECHT

(1551-1611)(1551-1611)

Mechanism of damageMechanism of damage Thyroid hormone is essential for normal Thyroid hormone is essential for normal

brain gene expressionbrain gene expression– NeurogenesisNeurogenesis– MyelinationMyelination– MigrationMigration– DifferentiationDifferentiation

Classical sensitive window in the Classical sensitive window in the developing braindeveloping brain

Timing and Region dependent gradient of Timing and Region dependent gradient of sensitivitysensitivity

Endemic CretinismEndemic Cretinism Occurs in areas of Occurs in areas of

severe iodine severe iodine deficiency and deficiency and almost universal almost universal endemic goitreendemic goitre

Geographic Geographic clusteringclustering

Two predominant Two predominant clinical phenotypesclinical phenotypes

Endemic Cretinism: Clinical Endemic Cretinism: Clinical PhenotypesPhenotypes

NeurologicalNeurological– EuthyroidEuthyroid– GoitrousGoitrous– Severe mental Severe mental

disabilitydisability– DeafnessDeafness– Neurological Neurological

abnormalitiesabnormalities– More frequentMore frequent

MyxedematousMyxedematous– HypothyroidHypothyroid– Thyroid atrophyThyroid atrophy– Severe mental Severe mental

disabilitydisability– DeafnessDeafness– Neurological Neurological

abnormalitiesabnormalities– Less frequentLess frequent

THEORIESTHEORIES1. Dualistic Theory 1. Dualistic Theory

2. Bipolar Theory2. Bipolar Theory

3. Two-step Theory3. Two-step Theory

HypothesisHypothesis That a combination of maternal and That a combination of maternal and

fetal hypothyroidism accounts for the fetal hypothyroidism accounts for the neurological manifestations of endemic neurological manifestations of endemic cretinism; ipsi facto all cretins should cretinism; ipsi facto all cretins should display evidence of neurological display evidence of neurological damagedamage

That postnatal factors determine the That postnatal factors determine the final “phenotypic” appearancefinal “phenotypic” appearance

ParadigmParadigm

Th yro id

Th yro id B ra in

Th yro id

F et us

M ot her

N eonat e

Child / A dult

I odine D efi ciency

Prenatal

Postnatal

EpidemiologyEpidemiologyGeographical clustering of phenotypeGeographical clustering of phenotype

ROLE OF MATERNAL ROLE OF MATERNAL GOITREGOITRE

Fodéré (1796)Fodéré (1796)– "if both parents have goitre, they always have "if both parents have goitre, they always have

the misfortune to produce children with certain the misfortune to produce children with certain degrees of cretinism"degrees of cretinism"

McCarrison (1908)McCarrison (1908)– Goitre was present in 96%Goitre was present in 96% of mothers who had of mothers who had

given birth to cretinsgiven birth to cretins Eugster (1938)Eugster (1938)

– No genetic linkageNo genetic linkage– The risk of bearing cretinous children increased The risk of bearing cretinous children increased

with advancing age and for late-born childrenwith advancing age and for late-born children

HISTORICAL PERSPECTIVEHISTORICAL PERSPECTIVE McCarrison (1908, McCarrison (1908,

1917)1917)– Classified endemic Classified endemic

cretins into two cretins into two typestypes

– NERVOUSNERVOUS

– MYXOEDEMATOUSMYXOEDEMATOUS

McCarrison (1908, 1917)McCarrison (1908, 1917) "nervous" for "want of a better term""nervous" for "want of a better term" "cases commonly presented the "cases commonly presented the

clinical features of a combination of clinical features of a combination of these"these"

"deaf-mutism is an almost common "deaf-mutism is an almost common accompaniement of both types of the accompaniement of both types of the disease"disease"

HISTORYHISTORY Resurgence of interest in Resurgence of interest in

iodine deficiency disorders iodine deficiency disorders in the 1950's and 1960'sin the 1950's and 1960's– Western New Western New

GuineaGuinea Gajdusek (1962)Gajdusek (1962) Choufoer (1965)Choufoer (1965)

– Eastern New Eastern New GuineaGuinea McCullagh McCullagh

(1963)(1963)

– Brazil Brazil Lobo (1963)Lobo (1963)

– ZaireZaire Bastenie (1962)Bastenie (1962) Dumont (1963)Dumont (1963) Delange (1972)Delange (1972)

DILEMMADILEMMA The problem posed for these The problem posed for these

researchers was to account for the researchers was to account for the unusually broad range of clinical unusually broad range of clinical findingsfindings

Syndrome of abnormalities observed Syndrome of abnormalities observed in most endemias did not fit with in most endemias did not fit with "typical" cretins."typical" cretins.

Querido (1975)Querido (1975) "After we had completed our studies, "After we had completed our studies,

we had great difficulty in convincing we had great difficulty in convincing others of our conclusions, even after others of our conclusions, even after demonstrating the older descriptions demonstrating the older descriptions of endemic cretinism! When reading of endemic cretinism! When reading the older literature we apparently were the older literature we apparently were not prepared to recognize that the not prepared to recognize that the clinical picture of endemic cretinism clinical picture of endemic cretinism was different from sporadic cretinism."was different from sporadic cretinism."

PathophysiologyPathophysiology The initial approach to the variable The initial approach to the variable

and conflicting findings of endemic and conflicting findings of endemic cretinism was to adopt McCarrison's cretinism was to adopt McCarrison's classification.classification.

Neurological Neurological foetal hypothyroidismfoetal hypothyroidism Myxoedematous Myxoedematous late foetal and late foetal and ppostnatal ostnatal

hypothyroidismhypothyroidism

Argument for the dual Argument for the dual hypothesishypothesis

The strongest argument for a different The strongest argument for a different pathogenesis for the two types of pathogenesis for the two types of endemic cretin was the virtual endemic cretin was the virtual absence of signs of neurological absence of signs of neurological damage in "myxoedematous" cretins.damage in "myxoedematous" cretins.

This was explained on the basis of the This was explained on the basis of the timing of the hypothyroid insult to the timing of the hypothyroid insult to the foetus and the neonate.foetus and the neonate.

1008060402000

Delange (1972)

Ibbertson (1971)

Fierro-Benitez (1970)

Choufoer (1965)

Lobo (1963)

Dumont (1963)

Bastenie (1962)

McCarrison (1908)

Neurological cretinsHypothyroid cretins with neurological signs"Myxoedematous" cretins

Frequency (%)

1008060402000

Halpern (1988)

Boyages (1988)

Chaouki (1988)

Delong (1987)

Squatrito (1981)

Delange (1981)

Djokomoeljanto (1974)

Pharoah (1972)

Neurological cretinsHypothyroid cretins with neurological signs"Myxoedematous" cretins

Frequency (%)

DUALISTIC THEORYDUALISTIC THEORY BIPOLAR THEORYBIPOLAR THEORY

– These hypotheses and subsequent These hypotheses and subsequent modifications that followed did not modifications that followed did not explain why severe iodine deficiency explain why severe iodine deficiency of a similar magnitude should of a similar magnitude should selectively impair prenatal thyroid selectively impair prenatal thyroid hormone levels in some, but not hormone levels in some, but not others. others.

HypothesisHypothesis That a combination of maternal and That a combination of maternal and

fetal hypothyroidism accounts for the fetal hypothyroidism accounts for the neurological manifestations of endemic neurological manifestations of endemic cretinism; ipsi facto all cretins should cretinism; ipsi facto all cretins should display evidence of neurological display evidence of neurological damagedamage

That postnatal factors determine the That postnatal factors determine the final “phenotypic” appearancefinal “phenotypic” appearance

Findings: Neurological FeaturesFindings: Neurological Features We found a similar pattern of neurological We found a similar pattern of neurological

involvement in nearly all cretins from both involvement in nearly all cretins from both endemias, regardless of type (myxoedematous or endemias, regardless of type (myxoedematous or neurological), and of current thyroid functionneurological), and of current thyroid function

Characteristic and specificCharacteristic and specific Mental retardationMental retardation DeafnessDeafness Pyramidal disturbancePyramidal disturbance Extrapyramidal dysfunctionExtrapyramidal dysfunction Gait disorderGait disorder

– Halpern JP, Boyages SC et al; Brain Halpern JP, Boyages SC et al; Brain Brain, Vol 114, Issue 2 825-Brain, Vol 114, Issue 2 825-841, Copyright © 1991 by Oxford University Press 841, Copyright © 1991 by Oxford University Press

The pattern of neurological The pattern of neurological damage reflects time and damage reflects time and

regional sensitivity to regional sensitivity to thyroid hormone deficiencythyroid hormone deficiency

Damage to:Damage to:– CochleaCochlea– Cerebral cortexCerebral cortex– Basal gangliaBasal ganglia– Disordered thalamic projectionsDisordered thalamic projections

Why are certain parts of brain Why are certain parts of brain predisposed? predisposed?

Timing of the insult and Timing of the insult and preferential sites for thyroid preferential sites for thyroid

hormone actionhormone action

Postnatal thyroid function Postnatal thyroid function modifies the clinical phenotypemodifies the clinical phenotype Neurological cretinsNeurological cretins

– GoitrousGoitrous

Myxoedematous Myxoedematous cretinscretins– Thyroid atrophyThyroid atrophy

Exhaustion atrophyExhaustion atrophy Goitrogenic effect eg SCNGoitrogenic effect eg SCN Selenium deficiencySelenium deficiency Autoimmune effect, blocking antibodiesAutoimmune effect, blocking antibodies Combination of factorsCombination of factors

Brain Damage: Shift in the IQ Brain Damage: Shift in the IQ distribution to the leftdistribution to the left

The neurological sequelae are not an all or The neurological sequelae are not an all or none phenomenonnone phenomenon

The population distribution of cognitive The population distribution of cognitive function shows a marked shift to the left function shows a marked shift to the left towards lower IQ scorestowards lower IQ scores

10 to 15 IQ points10 to 15 IQ points

20-2

9

30-3

9

40-4

9

50-5

9

60-6

9

70-7

9

80-8

9

90-9

9

100-

109

110-

119

120-

129

130-

139

140-

149

0

10

20

Iodine deficient (pre-prophylaxis)

Rural control (old)

City controls

City controls

Intelligence Quotient (IQ)

Frequency (%)

BEFORE IODISEDSALT PROPHYLAXIS

OutlineOutline Nutritional DisordersNutritional Disorders Principles of thyroid physiologyPrinciples of thyroid physiology Iodine physiologyIodine physiology What is a normal iodine level?What is a normal iodine level? How do we adapt to iodine deficiency?How do we adapt to iodine deficiency? Iodine Deficiency DisordersIodine Deficiency Disorders

– Iodine and brain damageIodine and brain damage Are we at risk?Are we at risk? Iodine ExcessIodine Excess Prevention and Food FortificationPrevention and Food Fortification

Are iodine levels Are iodine levels falling?falling?

Are we at risk?Are we at risk?

Are iodine levels falling?Are iodine levels falling?

Figure 1. (A) Median U.S. urinary iodine concentrations in males and females, 1971-2002 (B) Median U.S. urinary iodine concentrations in pregnant and non-pregnant women of child-bearing age (15- 44 years old), 1971-2002.[Adapted from Hollowell et al, JCEM 1998; 83:3401-8 & Caldwell et al, Thyroid 2005;15:692-9]

Pregnancy increases risk of Pregnancy increases risk of iodine deficiencyiodine deficiency

Iodine Deficiency in Iodine Deficiency in AustraliaAustralia

TasmaniaTasmaniaUrine Iodine DistributionUrine Iodine Distribution

Median UIE 84mcg/l

Thyroid Size: Boys and GirlsThyroid Size: Boys and Girls

24.6% 20.7%

Other StatesOther States

NINS studyNINS study Overall, children in mainland Australia are borderline

iodine deficient, with a national median UIE of 104 mcg/L.

On a state basis, NSW and Victorian children are mildly iodine deficient, with median UIE levels of 89 mcg/L and 73.5 mcg/L, respectively. South Australian children are borderline iodine deficient, with a median UIE of 101 mcg/L.

Both Queensland and Western Australian children are iodine sufficient, with median UIE levels of 136.5 mcg/L and 142.5 mcg/L, respectively.

There was no significant association between UIE and thyroid volume.

OutlineOutline Nutritional DisordersNutritional Disorders Principles of thyroid physiologyPrinciples of thyroid physiology Iodine physiologyIodine physiology What is a normal iodine level?What is a normal iodine level? How do we adapt to iodine deficiency?How do we adapt to iodine deficiency? Iodine Deficiency DisordersIodine Deficiency Disorders

– Iodine and brain damageIodine and brain damage Are we at risk?Are we at risk? Iodine ExcessIodine Excess Prevention and Food FortificationPrevention and Food Fortification

Just eat sushi! Is that ok?Just eat sushi! Is that ok?

What is normal intake?What is normal intake?Too little and Too much can be Too little and Too much can be

a problema problem

ENDEMIC GOITRE IN CENTRAL CHINA ENDEMIC GOITRE IN CENTRAL CHINA CAUSED BY EXCESSIVE IODINE INTAKECAUSED BY EXCESSIVE IODINE INTAKE

Thyroid status was examined in children from two Thyroid status was examined in children from two villages in China where the iodine concentrations in villages in China where the iodine concentrations in drinking water were 462.5 and 54 μg/1drinking water were 462.5 and 54 μg/1

Goitres were present in 65% (n = 120) and 15.4% Goitres were present in 65% (n = 120) and 15.4%

(n=51), respectively. (n=51), respectively.

Children from the high-iodine village had a lower Children from the high-iodine village had a lower mean serum triiodothyronine and higher serum free mean serum triiodothyronine and higher serum free thyroxine and serum thyroid-stimulating hormone thyroxine and serum thyroid-stimulating hormone concentrations than the children from the control concentrations than the children from the control village. 2 cases of overt hypothyroidism were village. 2 cases of overt hypothyroidism were detected in the high-iodine village.detected in the high-iodine village.

TOPICAL IODINE-CONTAINING ANTISEPTICS AND NEONATAL TOPICAL IODINE-CONTAINING ANTISEPTICS AND NEONATAL HYPOTHYROIDISM IN VERY-LOW-BIRTHWEIGHT INFANTS: HYPOTHYROIDISM IN VERY-LOW-BIRTHWEIGHT INFANTS:

P. Smerdely, S. C. Boyages, et al. Lancet 1989P. Smerdely, S. C. Boyages, et al. Lancet 1989

The thyroid function of very-low-birthweight (VLBW; below 1500 g) The thyroid function of very-low-birthweight (VLBW; below 1500 g) infants admitted to neonatal intensive-care units was studied at two infants admitted to neonatal intensive-care units was studied at two hospitals; one routinely used topical iodinated antiseptic agents and hospitals; one routinely used topical iodinated antiseptic agents and the other used chlorhexidine-containing antiseptics. the other used chlorhexidine-containing antiseptics.

Serial Urinary iodine excretion rose dramatically in the 54 iodine-Serial Urinary iodine excretion rose dramatically in the 54 iodine-exposed infants and was up to fifty times greater than in the 29 non-exposed infants and was up to fifty times greater than in the 29 non-exposed infants. exposed infants.

Within 14 days, 25% (9 of 36) of the infants exposed to iodine had Within 14 days, 25% (9 of 36) of the infants exposed to iodine had serum thyrotropin levels above 20 mIU/l, compared with none of the serum thyrotropin levels above 20 mIU/l, compared with none of the control group.control group.

The mean serum thyroxine level in these 9 infants (44·1 nmol/l) was The mean serum thyroxine level in these 9 infants (44·1 nmol/l) was significantly lower than that in exposed infants with normal significantly lower than that in exposed infants with normal thyrotropin levels (83·1 nmol/l) and in the non-exposed control group thyrotropin levels (83·1 nmol/l) and in the non-exposed control group (83·0 nmol/l), thyroxine levels fell before serum thyrotropin rose. (83·0 nmol/l), thyroxine levels fell before serum thyrotropin rose.

MedicationsMedications

Amiodarone related thyroid Amiodarone related thyroid diseasedisease

OutlineOutline Nutritional DisordersNutritional Disorders Principles of thyroid physiologyPrinciples of thyroid physiology Iodine physiologyIodine physiology What is a normal iodine level?What is a normal iodine level? How do we adapt to iodine deficiency?How do we adapt to iodine deficiency? Iodine Deficiency DisordersIodine Deficiency Disorders

– Iodine and brain damageIodine and brain damage Are we at risk?Are we at risk? Iodine ExcessIodine Excess Prevention and Food FortificationPrevention and Food Fortification

Percentage of households with Percentage of households with access to iodised saltaccess to iodised salt

Food FortificationFood Fortification Eradication of iodine deficiency has always the highest Eradication of iodine deficiency has always the highest

priority.priority. Optimal prevention of thyroid disease by modification of Optimal prevention of thyroid disease by modification of

iodine intake in the population is achieved by keeping iodine iodine intake in the population is achieved by keeping iodine intake in individuals within a relatively narrow interval intake in individuals within a relatively narrow interval around the recommended level. around the recommended level.

To run an optimal iodization program it is necessary to have To run an optimal iodization program it is necessary to have information on dietary habits in the population, and on iodine information on dietary habits in the population, and on iodine contents of different food items. contents of different food items.

Iodine used for enrichment of food should be well distributed Iodine used for enrichment of food should be well distributed in different food items, e. g. by universal or nearly universal in different food items, e. g. by universal or nearly universal iodization of salt. Optimal methods may differ between iodization of salt. Optimal methods may differ between European countries depending on dietary habits. European countries depending on dietary habits.

Risks of iodisation programmesRisks of iodisation programmes Sudden increase in the prevalence of Sudden increase in the prevalence of

hyperthyroidismhyperthyroidism– Jod Basedow phenomenonJod Basedow phenomenon

Development of hypothyroidism in those Development of hypothyroidism in those with pre-existing autoimmune thyroid with pre-existing autoimmune thyroid diseasedisease– Positive anti-TPO antibodiesPositive anti-TPO antibodies

Change in the pattern of thyroid disease, Change in the pattern of thyroid disease, rise in the prevalence of thyroid rise in the prevalence of thyroid autoimmunityautoimmunity

CONCLUSIONCONCLUSIONThyroid hormone is essential for Thyroid hormone is essential for

normal somatic and neurological normal somatic and neurological development. development.

Iodine deficiency leads to thyroid Iodine deficiency leads to thyroid hormone deficiency at critical periods hormone deficiency at critical periods of brain development that leads to of brain development that leads to irreversible neurological damage.irreversible neurological damage.

Prevention of iodine deficiency is Prevention of iodine deficiency is essentialessential

AcknowledgementsAcknowledgements AustraliaAustralia

– CJ EastmanCJ Eastman– JP HalpernJP Halpern– John K CollinsJohn K Collins– Li MuLi Mu

ChinaChina IndonesiaIndonesia The NetherlandsThe Netherlands

– Hemmo DrexhageHemmo Drexhage USA, AtlantaUSA, Atlanta

– GF MaberlyGF Maberly Italy, PisaItaly, Pisa

– Alessandro AntonelliAlessandro Antonelli