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UNSW Embryology

Abnormal Development - Iodine Deficiency

© Dr Mark Hill (2011)

Acknowledgements

Introduction

New Embryology Site

New 2011 Iodine Deficiency

Iodine deficiency disorders (IDD) is the single most common cause of preventable mental retardation and brain damage in the world. Iodine (Greek, ioeides = violet) is required for the synthesis of thyroid hormone, a key regulator of neurological development. IDD causes goiters and decreases the production of hormones vital to growth and development.

(More? Endocrine Development - Thyroid)

 

 Salt Shaker
  • 1.6 billion people are at risk
  • IDD affects 50 million children
  • 100,000 cretins are born every year

Children with IDD can grow up stunted, apathetic, mentally retarded and incapable of normal movement, speech or hearing. IDD in pregnant women cause miscarriage, stillbirth and mentally retarded children. A teaspoon of iodine is all a person requires in a lifetime, but because iodine cannot be stored for long periods by the body, tiny amounts are needed regularly. In areas of endemic iodine deficiency, where soil and therefore crops and grazing animals do not provide sufficient dietary iodine to the populace, food fortification and supplementation have proven highly successful and sustainable interventions. Iodized salt programs and iodized oil supplements are the most common tools in the fight against IDD.

Iodine incorporated into thyroid horomone, Thyroxine (T4)

(Information from International Council for the Control of Iodine Deficiency Disorders)

Some Recent Findings

Food Standards Australia New Zealand (FSANZ) - 22nd Australian Total Diet Study A total diet study of five trace elements: iodine, selenium, chromium, molybdenum, and nickel (More? Abnormal Development - Iodine Deficiency | Endocrine Development - Thyroid

"Whilst the majority of Australians had dietary intakes approaching or above the estimated average requirement (EAR) or AI for selenium, molybdenum and chromium, a substantial proportion of the population had iodine intakes below the EAR. FSANZ has subsequently commissioned further analyses of iodine levels in Australian foods and will be introducing mandatory fortification of iodine in bread, from September 2009."

Goodman JH, Gilbert ME. Modest Thyroid Hormone Insufficiency during Development Induces a Cellular Malformation in the Corpus Callosum: A Model of Cortical Dysplasia. Endocrinology. 2007 Jun;148(6):2593-7. (Rodent study)

Salt

The World Health Organization has made progress recently since the primary intervention strategy for IDD control, Universal Salt Iodization (USI), was adopted in 1993. Iodization can be carried out using potassium iodide or potassium iodate; or sodium iodide or sodium iodate.

Salt was chosen because it is widely available and consumed in regular amounts throughout the year, and because the costs of iodizing it are extremely low - only about US$0.05 per person per year.

Where salt iodization has been in place for over five years, improvement in iodine status has been overwhelming.Over the last decade, the number of countries with salt iodization programmes doubled, rising from 46 to 93. As a result, today 68% of the 5 billion people living in countries with IDD have access to iodized salt and the global rates of goitre, mental retardation and cretinism are falling fast.

(some text information from WHO page)

Iodine Requirements

The current WHO recommended daily iodine intakes are:

(More? World Health Organization - Micronutrient deficiencies Eliminating iodine deficiency disorders | World Health Organization - Iodine data by country)

I - Iodine

This information is about Iodine the element, dietry intake is in the form of iodine as a salt. The solid halogen was discovered in 1811 by Bernard Courtois (1777-1838) in seaweed. Iodine (Greek, ioeides = violet) was named for the color of its vapour.

Australia New Zealand Food Standards Code STANDARD 2.10.2 SALT AND SALT PRODUCTS

Australian Data

(from IDD Prevalence and Control Program Data)

(For other countries see also IDD Regional Data Page)

IDD Prevalence and Control Program Data

Last Modified: 6/98

Australia

I. IDD Prevalence

Goitre:

No national IDD data. Goiter historically limited to mountains of east and Tasmania. Before prophylaxis was introduced in 1950, IDD was greater than 50%. Presently, IDD not likely.

Cretinism:

Not present

TSH:

Neonatal TSH in screening shows levels compatible with iodine sufficiency, including Tasmania.

Urinary Iodine:

Current values: Tasmania 229-356 mcg/L, Sydney 180 mcg/L.

II. Salt Legislation

III. IDD Coordination

IDD Responsible Parties:

No national surveillance program

IV. Salt Supply

Iodized table salt has been available for over 50 years. However, noniodized salt is preferred and data indicate that less than a third of the consumed salt is iodized.

V. Supplementation:

Iodized bread was introduced in 1963 in Canberra and in 1966 in Tasmania. It continues to be a source of iodine.

VI. Monitoring Activities

The following indicators are available to monitor IDD:

VII. Comments

Dietary diversification and use of iodine in farm animals has contributed to iodine sufficiency, and iodine deficiency does not appear a current problem. However, no national surveillance system exists. Recent informal reports raise questions of return of iodine deficiency to Tasmania and assessment is underway (1998).

VIII. Sources

IDD NL 9(1):11, 1993

Australia New Zealand Food Standards Code STANDARD 2.10.2 SALT AND SALT PRODUCTS

WWW Links

Australian NHMRC

The Australian NHMRC (1988) recommends neonates be assessed for follow-up care under the following conditions.

(see the NHMRC WWW Page)

For Normal Childhood Development see Publications (or NHMRC WWW Page)

References

Where to Next?

You should look at normal development. Development Notes

Alternatively, go on to look at Systematic Development of organs and tissues.

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