Suplementação de iodo em gestantes : uma revisão sistemática.

Abstract

Introduction: Iodine is an essential element for the body, closely related to the synthesis of thyroid hormones. In pregnancy, the production of these hormones increases by almost 50%, together with an increase in renal excretion of iodine. Due to these factors and the demand for fetal iodine, dietary iodine requirements are higher in pregnant adults; therefore, there is controversy about the need for iodine supplementation in these women. Normal levels of these hormones are essential for neuronal migration and fetal brain myelination. Iodine deficiency affects both maternal and fetal thyroid hormone production and insufficient iodine intake can lead to harmful effects. Urine iodine concentration (UIC) is the measurement used to ascertain the iodine intake of individuals performing an analytical study of this substance. According to the WHO, it is considered that a pregnant woman should have a daily intake of iodine of about 250μg so that there is no lack of this micronutrient. Goals: To elaborate a systematic review to analyze the evidences on the necessity of iodine supplementation, its possible risks and benefits. Methodology: This was a systematic review of clinical studies using the descriptors "thyroid", "pregnancy" and "iodine supplementation" in the MEDLINE / PubMED, LILACS and Scopus electronic databases from March 2008 to March. 2018. Results: The number of pregnant women studied together with all articles was 2674. The method used to evaluate the iodine intake in pregnant women was the UIC, being the method of choice 88.89% of the articles analyzed. The studies presented supplementation doses ranging from 150 to 400 (μg / day), with 88.89% of the articles evaluating to some extent the supplementation with 150 μg / day. In 6 studies (66.67% of the total) the patients were supplemented during the three trimesters of gestation. Conclusion: The safe upper limits for iodine intake in pregnancy are not well defined and more evidence is needed about the safety and efficacy of supplementation during pregnancy before being systematically recommended for all pregnant women.