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بسـم الله الرحمن الر حیـم

هوالطیف

Overview of Overview of IDD assessment IDD assessment and indicators and indicatorsH. Delshad M.DEndocrinologistResearch Institute for Endocrine Sciences

IDDIDD: Iodine Deficiency Disorders: Iodine Deficiency Disorders

The world’s most common endocrine problem

The most preventable cause of mental retardation

The easiest of the major nutritional deficiencies to correct

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WWhat hat isis Iodine Iodine??

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● ● Iodine is a chemical element Iodine is a chemical element ( as are Oxygen ,Hydrogen , Iron ) ( as are Oxygen ,Hydrogen , Iron ) occurs in a variety of chemical formsoccurs in a variety of chemical forms

●● Iodine is an essential trace Iodine is an essential trace element for the humanelement for the human

●● Iodine is an essential Iodine is an essential part of the chemical part of the chemical structure of thyroid structure of thyroid hormoneshormonesTotal quantity present in body is (15-20 mg)

Mostly in thyroid gland

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What does iodine do? And

Why do we need iodine?

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Thyroid hormones synthesis

requires:

◦Normal thyroid gland◦Adequate secretion of T.S.H

◦Availability of iodine

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IodineIodineThe average adult body contains

between 20-50 mg iodine.60% of total iodine is

concentrated in thyroid gland. Iodine is an essential component

of the thyroid hormones. Iodine contributes 65% of T4 and

59% of T3 molecular weight.

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Thyroid horm

one synthesis

How much iodine should

we get?

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Recommended daily intake Recommended daily intake of iodineof iodine

Preschool children 90 g

Schoolchildren (6-12 y) 120 g

Adult (>12 y) 150 g

Pregnant & Lactating women

250 g

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Where do we get iodine from?

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Source of iodine

Water Food

Most of the iodine ingested by humans comes from food of animal and plant origin.

This iodine in turn, is derived from the soil.

Only a relatively small fraction is derived from drinking water.

Worldwide soil distribution of iodine is extremely variable & food grown in areas of low iodine does not contain enough of the mineral to meet requirements.

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Iodine sourcesIodine sources

Iodine sourcesIodine sources

Vegetables grown in iodine rich soil like kelp and onions

Milk & milk productSalt water fish and seafood

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Iodine deficiency – Disease of the soilIodine deficiency – Disease of the soil

Melting of Glaciers

Floods

Rivers changing course

Gradual leaching of iodine from soil due to:

Iodine deficient areasIodine deficient areas

Large population who are living in an environment where the soil has been deprived of iodine are at risk of IDD. ◦Mountainous region of Europe◦The northern Indian subcontinent◦The extensive mountain ranges of

china◦The Andean region in South America

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What happens if we don’t get

enough iodine?

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Mechanisms involved in the adaptation Mechanisms involved in the adaptation to iodine deficiencyto iodine deficiency

Increased thyroid clearance of plasma inorganic iodine.

Hyperplasia of the thyroid and morphologic abnormalities

Changes in iodine stores & TG synthesisModifications of the iodoamins acid

content of the gland.Enrichment of thyroid secretion in T3Enhanced peripheral conversion of T4 to

T3Increased T.S.H production

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The spectrum of The spectrum of IDDIDDFetus Abortions

StillbirthsCongenital anomaliesIncreased perinatal mortalityNeurologic creatinismPsychomotor defects

Neonate Neonatal goiterNeonatal hypothyroidims

Child & adolescent Goitrous juvenile hypothyroidism Impaired mental function Retarded physical development

Adult Goiter with its complications HypothyroidismImpaired mental function

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IDDIDD : Spectrum of Disorders : Spectrum of DisordersIDDIDD : Spectrum of Disorders : Spectrum of Disorders

From SIMPLE GOITER

Large MNG

Hypothyroidism

Severe myxedema

IQ

Psycho motor alteration

Deaf- Mutism

Diplegia

Retarded growth

.

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To CRETINISM

Specific iodine deficiency Specific iodine deficiency disordersdisorders

Endemic goiterEndemic cretinism

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Endemic goiterEndemic goiter

More than 5% of the preadolescent (6-12 years) school age children have enlarged thyroid glands.

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Simple (nontoxic goiter)

WHO Region Population Population affected by goitre

In millions In millions % of the Region

Africa

612 122 20%

The Americas

788 39 5%

South-East Asia

1477 172 12%

Europe

869 130 15%

Eastern Mediterranean

473 152 32%

Western Pacific

1639 124 8%

Total 5858 741 13%

World wide prevalence of goiter

Pathogenesis of goiter Pathogenesis of goiter

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Impaired hormone synthesis • Iodine deficiency • Goitrogen in the diet• Dyshormogenesis

T.SH Alter sensitivity

Thyroid follicular cellHyperplasia and hypertrophy

Thyroid enlargement (GOITER)

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Three women of the Himalayas with typical endemic goiters.

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Huge Multinodular goiter

Iodine deficiency in the Iodine deficiency in the fetusfetus

Mental retardation:◦Is the result of iodine deficiency in

the mother◦Insufficient supply of TH to the

developing brain may result in mental retardation.

◦During the first and second trimesters of pregnancy the supply of the TH to the growing fetus is almost exclusively of maternal origin.

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Importance of iodine in brain development Importance of iodine in brain development

50,000 brain cells produced per

Second in developing fetal brain

90 % of human brain development occurs between 3rd month of

pregnancy & 3rd year of life

(Critical period)

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Importance of iodine in brain development Importance of iodine in brain development

Deficiency of iodine during this critical period of

development results in permanent brain damageThis brain damage can primarily be prevented by

correcting iodine deficiency before & during

pregnancyThis makes it vital that all expectant & lactating

mothers get their daily requirement of iodine

Importance of iodine in brain development Importance of iodine in brain development

Iodine deficiency is single most common cause of mental handicap worldwide

It is totally preventable

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Congenital Hypothyroidism

Endemic CretinismEndemic Cretinism

Is now largely a disease in remote, underdeveloped areas of the third world.

It occurs when iodine intake is below a critical level of 25 g/day

It is an irreversible changes in mental development of the fetus born in an area of endemic goiter.

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1% - 10%

Cretinism

5% - 30%

Some brain damage

30% - 70%

Loss of energy due to hypothyroidism

Cretinism, Tip of the Iceberg

Endemic CretinismEndemic Cretinism(Neurologic Form)(Neurologic Form)

Sever mental deficiencyDeaf mutism (Cochlear lesion)Motor spasticity (spastic diplegia) proximal rigidity of both lower and upper extremities and the trunk. Goiter

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Endemic CretinismEndemic Cretinism(Neurologic Form)(Neurologic Form)

Endemic CretinismEndemic Cretinism(Myxedematous Form)(Myxedematous Form)

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Less sever degree of mental retardation Sever growth retardationPuffy featuresMyxedematous and dry skinDelayed sexual maturation No goiter

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An adult male from the Congo,

with three women of the same

age (17-20 years),

all of whom are myxedematous cretins.

Myxedematous Cretinism

Myxedematous Myxedematous CretinismCretinism

Iodine deficiency is a prerequisite in the etiology of the disorder.

Three additional factors, acting alone or in combination may be responsible for thyroid atrophy. ◦Thiocyanate overload resulting from the

chronic consumption of poorly detoxified cassava.

◦Thiocyanate crosses the placenta and inhibits the trapping of iodine by the placenta and fetal thyroid.

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Cont’dCont’d

◦Selenium deficiency:H2O2 is produced in excess in thyroid

cells hyperstimulated by T.S.H H202 within the thyroid cells couldinduce thyroid cell destruction.

Selenium detoxifies H202 ◦Blocking autoantibiotdies.

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Specific Etiologies of Specific Etiologies of GoiterGoiter

Congenital goiter◦Familial: genetics disorders of

hormongenesis◦Sporadic:

Intrauterine iodide deficiency Fetal exposure to goitrogen (Antithyroid

drugs)

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Cont’dCont’dEndemic goiter

◦Iodine deficiency◦Dietary goitrogen

Cabbage Turnip Kale Rape Cassava

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Cont’dCont’d

Sporadic goiter Iodine excess

Wolff-chaikoff Jodbusedow

◦Goitrogenic drugs

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Drugs reported to cause goiterDrugs reported to cause goiter

Agent MechanismsIodide Inhibition of TH release and

synthesis

Thionamides Inhibition of tyrosyl iodination and coupling

Aminoglutethimide Inhibition of iodide organization

Lithium Inhibition of iodide organization

Amiodaron Inhibition of TH synthesis

Fluoride Exacerbation of effects of iodide deficiency

Carbutamide Decreased iodide uptake and inhibition of TH synthesis

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