Guidelines Summary
World Health Organization
The World Health Organization (WHO) recommended dietary allowance (RDA) of iodine is as follows [3] :
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Adults and adolescents: 150 mcg/day
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Pregnant and lactating women: 250 mcg/day
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Children aged 6-12 years: 120 mcg/day
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Infants to 6 years: 90 mcg/day
The WHO notes that although a reduction in the intake of salt to less than 5 g/day, on average, is needed to reduce cardiovascular risk, individuals still consume about 10 g/day, most from household salt used for home cooking and at the table. Therefore, the WHO strongly recommends all food-grade salt should be fortified with iodine as a safe and effective strategy for the population-based prevention and control of iodine deficiency disorders.
Additional recommendations include the following:
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Monitoring of salt intake and iodine intake is needed to adjust salt iodization as necessary to ensure that individuals consume sufficient iodine despite reduction of salt intake.
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Iodized salt should be used universally after the age of 1 year. Infants and young children are assumed to be covered via breast milk or iodine-enriched infant formula milk.
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Since pregnant women have a higher daily iodine requirement of 250 mcg/day, other interventions such as iodine supplementation could be considered if iodine inadequacy is found
Iodine Deficiency Prevention During Pregnancy
The following organizations have issued guidelines for the management of thyroid dysfunction during pregnancy, which include recommendations for management of iodine deficiency:
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Endocrine Society (ES)
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American Thyroid Association (ATA)
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European Thyroid Association (ETA)
The Endocrine Society (ES) guidelines offer the following recommendations for iodine nutrition during pregnancy [32] :
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Women of childbearing age should have an average iodine intake of 150 μg/day. Prior to conception, during pregnancy, and while breastfeeding, women should increase their intake to 250 μg/day.
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Iodine intake during pregnancy and breastfeeding should not exceed 500 μg/day.
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Once-daily prenatal vitamins should contain 150–200 μg iodine in the form of potassium iodide or iodate. Supplementation should be started before conception.
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Breastfeeding mothers should maintain a daily intake of 250 μg of iodine to ensure that breast milk provides 100 μg of iodine per day to the infant.
The American Thyroid Association (ATA) guidelines concur with the ES guidelines and include the following additional recommendations [33] :
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There is no need to initiate iodine supplementation in pregnant women who are being treated for hyperthyroidism or who are taking LT4.
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Excessive doses of iodine exposure during pregnancy should be avoided, except in preparation for the surgical treatment of Graves disease.
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Clinicians should carefully weigh the risks and benefits when ordering medications or diagnostic tests that will result in high iodine exposure.
The European Thyroid Association (ETA) recommends daily iodine intake during pregnancy, and lactation should be at least 250 μg and should not exceed 500 µg. Iodine intake should be supplemented with 150 μg of iodine/day, beginning prior to conception and continuing through lactation. [36]
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Iodine Deficiency. Distribution of iodine deficiency in developing countries.
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Iodine Deficiency. Typical endemic goiters in 3 women from the Himalayas, an area of severe iodine deficiency. Image courtesy of F. DeLange.
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Iodine Deficiency. A man and 3 females (age range, 17-20 y) with myxedematous cretinism from the Republic of the Congo in Africa, a region with severe iodine deficiency. Image courtesy of F. DeLange.
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Iodine Deficiency. Histologic sections from a normal thyroid and from an endemic goiter that was removed because of compressive symptoms. The normal thyroid (A) contains thyroid cells arranged in a monolayered sheet around a storage form of thyroid hormone, colloid, while the endemic goiter (B) shows intense hyperplasia with no colloid. Image courtesy of F. DeLange.
Tables
Iodine Deficiency |
None |
Mild |
Moderate |
Severe |
Median urine iodine, mcg/L |
>100 |
50-99 |
20-49 |
< 20 |
Goiter prevalence |
< 5% |
5-20% |
20-30% |
>30% |
Neonatal thyroid-stimulating hormone (TSH), >5 IU/mL whole blood |
< 3% |
3-20% |
20-40% |
>40% |
Cretinism |
0 |
0 |
+ |
+ |
Adapted from the World Health Organization (WHO)/United Nations Children's Fund (UNICEF)/International Council for Control of Iodine Deficiency Disorders (ICCIDD). |
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