From the Guidelines
Iodine supplementation is crucial for pregnant and lactating women, particularly in areas with iodine deficiency, with a recommended daily dose of 150 micrograms to prevent iodine deficiency disorders and ensure proper thyroid function. The thyroid gland plays a vital role in regulating metabolism, and iodine is essential for the production of thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3) 1. Insufficient iodine intake can lead to hypothyroidism, causing fatigue, weight gain, cold intolerance, and in severe cases, goiter (thyroid enlargement), while excessive iodine can trigger hyperthyroidism in susceptible individuals, particularly those with underlying thyroid conditions like Graves' disease or nodular goiter 1.
Iodine Requirements
The recommended daily intake of iodine varies by age and pregnancy status:
- Adults: 150 micrograms/day
- Pregnant women: 220 micrograms/day
- Breastfeeding women: 290 micrograms/day 1 It is essential to note that the Tolerable Upper Intake Level (UL) for adults is 1.1 mg/day, and there is no evidence that iodine intakes superior to the Dietary Reference Intake (DRI) are beneficial 1.
Iodine Supplementation
Iodine supplementation is recommended for pregnant and lactating women, especially in areas with iodine deficiency, to prevent iodine deficiency disorders and ensure proper thyroid function 1. The American Thyroid Association, the Endocrine Society, and the US National Academy of Sciences propose that all prenatal supplements should include 150 µg potassium iodide 1. However, it is crucial to consider the potential risks of iodine supplementation, including overactive thyroid function, nausea, and vomiting during pregnancy, particularly in areas with mild-to-moderate iodine deficiency 1.
Monitoring Thyroid Health
Regular thyroid function tests (TSH, T3, T4) can help monitor thyroid health in individuals concerned about iodine status or with thyroid disorders 1. It is essential to consult healthcare providers before taking iodine supplements, as self-supplementation can worsen existing thyroid conditions.
From the FDA Drug Label
Certain forms of iodine help your thyroid gland work right. The thyroid can “store” or hold only a certain amount of iodine. If you take KI, it will block or reduce the chances that radioactive iodine will enter your thyroid gland.
The relationship between iodine and the thyroid is that iodine is necessary for the thyroid gland to function properly. In a nuclear radiation emergency, taking potassium iodide (KI) can help block or reduce the uptake of radioactive iodine by the thyroid gland, thus preventing potential damage 2.
- Key points:
- Iodine is essential for thyroid function
- KI can block radioactive iodine uptake by the thyroid
- Certain thyroid conditions may require precautions when taking KI 2
From the Research
Iodine and Thyroid Function
- Iodine is a micronutrient essential for thyroid hormone production, and adequate intake is crucial during pregnancy and early life for brain development 3, 4.
- Iodine deficiency can result in inadequate production of thyroxine and related thyroid, metabolic, developmental, and reproductive disorders 4.
- The thyroid gland requires iodine to synthesize thyroid hormones, and iodine deficiency can lead to goiter, hypothyroidism, cretinism, and impaired cognitive development 4, 5.
Iodine Intake and Recommendations
- Iodine intake recommendations vary around the world, but most recommendations reflect the increased requirements during pregnancy and lactation 3.
- Adequate iodine intake before pregnancy is also important, and health organizations, governments, and clinicians should ensure that adequate iodine is consumed by everyone in the population 3.
- Iodized salt is the cornerstone of iodine prophylaxis in endemic areas, and continuous monitoring of community iodine intake and its related clinical outcomes is essential 4.
Effects of Excess Iodine Intake
- High iodine intakes are well tolerated by most healthy individuals, but excess iodine intakes may precipitate hyperthyroidism, hypothyroidism, goiter, and/or thyroid autoimmunity in some people 6.
- Individuals with preexisting thyroid disease or those previously exposed to iodine deficiency may be more susceptible to thyroid disorders due to an increase in iodine intake 6.
- The median urinary iodine concentration (UIC) of a population reflects the total iodine intake from all sources and can accurately identify populations with excessive iodine intakes 6.
Clinical Implications of Iodine Deficiency
- Potential consequences of iodine deficiency include goiter, hypothyroidism, cretinism, and impaired cognitive development 5.
- Iodine status in the United States is considered sufficient at the population level, but intake varies widely across the population, and the percentage of women of childbearing age with iodine deficiency is increasing 5.
- Physicians should be aware of the risks of iodine deficiency and the indications for iodine supplementation, especially in women who are pregnant or lactating 5.