Recent advances in the prevention of iodine deficiency disorders

Organización Panamericana de la SaludOrganización Mundial de la Salud

Recent advances in the prevention of iodine deficiency disorders

Ruben Grajeda

Pan American Health Organization


Contents

• Iodine deficiency disorders: Causes and consequences.

• Worldwide Iodine Status

• Recommended Nutrient Intake

• Methods to assess iodine status

• Urinary iodine concentrations in United States

• Urinary iodine concentrations in Pregnant and Childbearing age women form United States

• Iodine Excess

• Urinary Iodine Excretion in School Age Children in Latin American Countries

• Summary


Iodine supplementation not only eliminate new cases of cretinism buy also reduced infant mortality and improved

cognitive function in the rest of the population.

• Iodine is essential component of the hormones produced by the thyroid gland.

• Thyroid hormones regulate many key biochemical reactions, especially protein synthesis and enzymatic activity.

• Major target organs are the developing brain, muscle, heart, pituitary, and kidney.


Consequences

• Birth defects

• Increased risk for abortions and stillbirths

• Retarded physical growth

• Impaired mental functioning

• Cretinism

• Hypothyroidism

• Goiter

Iodine Deficiency Disorders

Iodine deficiency is the major cause of preventable mental retardation.

Causes

• Lack of iodine in natural food.


Strategies to Increase the Iodine Intake

Prevention Strategies

• Food Fortification

• Salt

• Bread

• Water

• Milk

• Iodine Supplementation

Prevalence

• Worldwide 2 billion people have insufficient iodine intake through the usual diet.

• In the Americas region 98 million people may suffer from insufficient iodine intake if additional supply is not ensured.

Salt iodization is the most cost effective intervention to prevent iodine deficiency disorders


Source: de Benoist B, McLean E, Andersson M, Rogers L. Iodine deficiency in 2007: global progress since 2003. Food Nutr Bull. 2008 Sep;29(3):195-202.


Recommended Nutrient Intake


Tolerable upper intake level


Methods to assess iodine status

• Thyroid size (population’s history of iodine nutrition and its present status)

• Urinary iodine concentration (indicator of recent iodine intake)

• Thyroid stimulating hormone, TSH (Useful biomarker in neonates, pregnant and lactating women)

• Thyroglobulin (Useful maker in children and adolescents)

• Thyroid hormone concentration



Source: Caldwell KL, Makhmudov A, Ely E, Jones RL, Wang RY. Iodine Status of the U.S. Population, National Health and Nutrition Examination Survey, 2005-2006 and 2007-2008. Thyroid. 2011 Feb 16.


Percent of the population with low urinary iodine in United States, 2007-2008. National Health and Nutrition

Examination Survey

< 100 µg/L < 50 µg/L < 20 µg/L

Percent of the population 28.2 8.8 1.1


Epidemiological criteria from the WHO for assessment of iodine nutrition in a population based on median or range of UI

< 20 µg/L Insufficient Severe iodine deficiency

20 – 49 µg/L Insufficient Moderate iodine deficiency

50 – 99 µg/L Insufficient Mild iodine deficiency

100 – 199 µg/L Adequate Optimum

200 – 299 µg/L More than adequate Risk of iodine-induce hyperthyroidism

> 300 µg/L Excessive Risk of adverse health consequences



Pregnant <150 µg/L Insufficient

150 – 249 µg/L adequate

250 – 499 µg/L More than adequate

> 500 µg/L Excesive

Nonpregnant <100 µg/L Insufficient

Women of Childbearing age in the United States and low urinary iodine concentrations by pregnancy status bases on National Health and Nutrition

Examination Survey (2005-2008)


Source: Higa AM, Miranda M, Campos M, Sánchez JR. Iodized salt intake in households and iodine nutritional status in women of childbearing age in Peru, 2008. Rev Peru Med Exp Salud Publica. 2010 Jun;27(2):195-200.

Proportion of household with Iodized salt in Peru, 2008


Source: Higa AM, Miranda M, Campos M, Sánchez JR. [Iodized salt intake in households and iodine nutritional status in women of childbearing age in Peru, 2008]. Rev Peru Med Exp Salud Publica. 2010 Jun;27(2):195-200.

Urinary iodine concentrations in fertile age women in Peru, 2008


Urinary Iodine Excretion in School Age Children in Latin American Countries

Source: Pretell, E. Grajeda, R. Iodine Nutrition in Latin America. IDD Newsletter 2009, 31;(1):1-5

More

than adequate Excessive


País

Last year

Median urinary iodine

Proportion of samples

50 y 99

µg/L 20-49µg/L

< 20 µg/L

Argentina (Salte) 2006 207.00 0.00 - -

Cuba 2005 214.50 8.40 2.30

Chile 2006 252.00 14.80 3.70 0.00

Ecuador 2006 257.45 10.52 0.00 0.00

Honduras 2005 356.00 7.30 2.00 0.00

Panamá 2006 209.30 5.50 0.40 0.00

Perú 2006 259.00 8.40 3.80 1.00

Venezuela 2005 185.00 - - -

Median urinary iodine in school age children in selected Latin American Countries 2004-2006.


Iodine Excess

• Iodine - Induce hypothyroidism autoimmune thyroiditis with chronic hypothyroidism

• Iodine – Induce hyperthyroidism after long-standing iodine deficiency (persons with goitres)

• Tolerable Upper Level:

– 600 mg per day in the European Union

– 100 mg per day in the United States. for adults


Summary

• Severe iodine deficiency in pregnancy can cause hypothyroidism, poor pregnancy outcome, cretinism, and irreversible mental retardation.

• Mild-to-moderate iodine deficiency in-utero and in childhood results in less severe learning disability, poor growth, and diffuse goiter.

• In adults, mild-to-moderate iodine deficiency appears to be associated with higher rates of more aggressive subtypes of thyroid cancer and increases risk for nontoxic and toxic nodular goiter and associated hyperthyroidism.


Summary

• In Latin American countries universal salt fortification has shown be effective to prevent iodine deficiencies.

• Even though population iodine status in the United States is adequate, pregnant women are at high risk of iodine deficiencies, just as women in other developed countries are.

• Urinary iodine concentration in some Latin American countries suggests an excess of iodine intake.

• In some countries iodine intake is to high that iodine additions levels and salt consumption must be reviewed and adjusted appropriately.

• Salt fortification programs should be monitored and evaluated to assure adequate iodine intake.


Thank you

Documents

Recent advances in the prevention of iodine deficiency disorders