Are Your Patients Iodine Deficient?

The importance of iodine supplementation in pregnant and lactating women was the topic of a viewpoint in a recent issue of the Journal of the American Medical Association.¹ The authors’ intention of highlighting iodine supplementation was to promote awareness in the health care community about the declining levels of iodine in the United States and the potential negative health implications associated with iodine deficiency.

Iodine deficiency during pregnancy is the leading cause of preventable intellectual impairments worldwide. In fact, there is some concern, says Elizabeth Pearce, MD, MSc, a coauthor of the viewpoint, that even a mild iodine deficiency in pregnancy can cause children to have lower IQs.¹ Insufficient levels of iodine can also cause maternal and fetal goiters, cretinism, neonatal hypothyroidism, and increased pregnancy loss and infant mortality.

Iodine, which must be consumed through food or supplements containing the element, is required for the production of thyroid hormone. The authors explain that because adequate thyroid hormone levels are required for normal fetal neurodevelopment, there is an increased need for iodine during pregnancy because of increased thyroid hormone production, increased renal iodine losses, and fetal iodine requirements.

Optimal iodine intake in pregnant women usually generates median urinary iodine values of between 150 and 249 micrograms/L. However, the authors cite that the most recent national data show that the median urinary iodine level for pregnant women in the United States was 125 micrograms/L. It has been recommended that pregnant women consume a minimum of 150 micrograms of potassium iodide daily. The latest recommendations from the US Institute of Medicine are that pregnant women should consume 220 micrograms of iodine daily and lactating women should consume 290 micrograms of iodine daily. However, these recommendations for daily iodine supplementation in women who are pregnant, lactating, or planning to become pregnant have largely been ignored.

The authors also point out that only 51% of prenatal multivitamins currently marketed in the United States contain iodine and that only 20% of pregnant women use these iodine-containing supplements. The authors advocate for the pharmaceutical industry to include at least 150 micrograms of iodine in all prenatal vitamins. Identifying which women are at risk for iodine deficiency is impossible. Therefore, the authors propose that it is the responsibility of every clinician to ensure that pregnant and lactating women receive supplemental iodine.

Pertinent Points:
- Iron deficiency is the leading cause of preventable intellectual impairments worldwide.
- Women who are pregnant should take a prenatal multivitamin that contains at least 150 micrograms of iodine.
 

References:

1. Stagnaro-Green A, Sullivan S, Pearce EN. Iodine supplementation during pregnancy and lactation. JAMA. 2012;308:2463-2464.