Recent advances in the prevention of iodine deficiency

Recent advances in the prevention of iodine deficiency disorders Ruben Grajeda Pan American Health Organization Organización Panamericana de la Salud Organización Mundial de la Salud

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 Organización Panamericana de la Salud Organización Mundial de la Salud

• 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. Iodine supplementation not only eliminate new cases of cretinism buy also reduced infant mortality and improved cognitive function in the rest of the population. Organización Panamericana de la Salud Organización Mundial de la Salud

Iodine Deficiency Disorders Causes • Lack of iodine in natural food. Consequences • Birth defects • Increased risk for abortions and stillbirths • Retarded physical growth • Impaired mental functioning • Cretinism • Hypothyroidism • Goiter Iodine deficiency is the major cause of preventable mental retardation. Organización Panamericana de la Salud Organización Mundial de la Salud

Strategies to Increase the Iodine Intake 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. Prevention Strategies • Food Fortification • Salt • Bread • Water • Milk • Iodine Supplementation Salt iodization is the most cost effective intervention to prevent iodine deficiency disorders Organización Panamericana de la Salud Organización Mundial de la Salud

Source: de Benoist B, Mc. Lean E, Andersson M, Rogers L. Iodine deficiency in 2007: global progress since Food Nutr Bull. 2008 Sep; 29(3): 195 -202. Organización Panamericana de la Salud Organización Mundial de la Salud

Recommended Nutrient Intake Organización Panamericana de la Salud Organización Mundial de la Salud

Tolerable upper intake level Organización Panamericana de la Salud Organización Mundial de la Salud

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 Organización Panamericana de la Salud Organización Mundial de la Salud

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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. Organización Panamericana de la Salud Organización Mundial de la Salud

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 28. 2 8. 8 1. 1 Percent of the population 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. Epidemiological criteria from the WHO for assessment of iodine nutrition in a population based on median or range of UI Organización Panamericana de la Salud Organización Mundial de la Salud < 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

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: 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. Pregnant Nonpregnant Organización Panamericana de la Salud Organización Mundial de la Salud <150 µg/L Insufficient 150 – 249 µg/L adequate 250 – 499 µg/L More than adequate > 500 µg/L Excesive <100 µg/L Insufficient

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. Organización Panamericana de la Salud Organización Mundial de la Salud

Urinary iodine concentrations in fertile age women 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. Organización Panamericana de la Salud Organización Mundial de la Salud

Urinary Iodine Excretion in School Age Children in Latin American Countries More than adequate Excessive Source: Pretell, E. Grajeda, R. Iodine Nutrition in Latin America. IDD Newsletter 2009, 31; (1): 1 -5 Organización Panamericana de la Salud Organización Mundial de la Salud

Median urinary iodine in school age children in selected Latin American Countries 2004 -2006. Proportion of samples Last year Median urinary iodine 50 y 99 µg/L 20 -49 µg/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 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 - - - País Organización Panamericana de la Salud Organización Mundial de la Salud

Iodine Excess • Iodine - Induce hypothyroidism autoimmune thyroiditis with chronic hypothyroidism • Iodine – Induce hyperthyroidism after long-standing iodine deficiency (persons with goitres) • Organización Panamericana de la Salud Organización Mundial de la Salud 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. Organización Panamericana de la Salud Organización Mundial de la Salud

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. Organización Panamericana de la Salud Organización Mundial de la Salud

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