Potential Preventive Effect of Selenium on Iodine-induced Thyroid Autoimmunity During Pregnancy

In 1994, the WHO and UNICEF Joint Committee on Health Policy recommended Universal Salt Iodization as a safe, cost-effective and sustainable strategy to ensure sufficient intake of iodine by all individuals. However, it is still absent in Latvia. A recent countrywide study in 2013 shows iodine deficiency among pregnant women in Latvia: 81 % of pregnant women had UIC levels below the WHO recommended range of 150-250 mcg/g Cr. Because mild to moderate iodine deficiency during pregnancy can adversely affect fetal brain development, WHO-UNICEF and ICCIDD advise an increase in the recommended daily dosage of iodine to 250 mcg/day for pregnant women and breastfeeding women and 150 mcg/day for women in the preconception period. Data from a survey of the Latvian population indicate that approximately 100 mcg of iodine per day is consumed through foods and iodized salt. To meet the increased iodine requirement in pregnancy, pregnant women should take a supplement containing 150 mcg of iodine daily from the earliest time possible. A sudden increase in iodine intake in an iodine-deficient population may increase thyroid autoimmunity. It is evident that thyroid disease has multiple adverse effects during pregnancy and in the developing fetus especially in women with elevated serum anti-thyroid antibody titers. Studies have considered supplementing with selenium to reduce the risk of auto-immune thyroiditis/post-partum autoimmune thyroid disease. Of the 11 trials of selenium supplementation in patients with autoimmune thyroiditis, 7 have shown benefit with treatment for 6 months or longer. Aim of study is to approve that 150 mcg of iodine daily improves iodine status in pregnant women and iodine 150 mcg in combination with selenium 100 mcg daily reduce risk of thyroid autoimmunity. Hypothesis of study is that 150 mcg iodine daily during pregnancy improves iodine status. Iodine in combination with selenium is less associated with thyroid autoimmunity. Study design: Pregna