Resumo

OLIVEIRA, Jaime Luís da Rocha; CARVALHO, Davide Maurício Costa  e  BELO, Sandra Patrícia Mota. Iodine intake and thyroid function in pregnancy. Rev Port Med Geral Fam [online]. 2018, vol.34, n.5, pp.288-306. ISSN 2182-5173.  https://doi.org/10.32385/rpmgf.v34i5.12094.

Aim: To review the published evidence relating iodine intake and thyroid function in pregnancy. Data source: MEDLINE, Scopus, Google Scholar and Scielo databases, as well as official documents from World Health Organization, American Thyroid Association, Iodine Global Network and Direção-Geral da Saúde. Review methods: Review of scientific articles focusing in humans’ species, written in English or Portuguese, and published between 01/01/1990 and 30/09/2016. These articles were searched through a query consisting of the MeSH terms ‘Iodine’, ‘Thyroid Gland’ and ‘Pregnancy’. Results: 107 articles were exhaustively analyzed, and data from 70 of them was included in this review, which were selected based on their scientific relevance. Due to the increased need of iodine during pregnancy and breastfeeding, its deficiency is more common during these periods. Even though mild/moderate, maternal iodine deficiency can affect the fetal neurodevelopment. In face of maternal iodine deficiency, physiological changes of the thyroid during pregnancy can become pathological, with a decrease of free hormones levels, an increase of TSH and an increase of the maternal and fetal thyroglobulin levels and thyroid volume. On the other hand, iodine supplementation during pregnancy appears to be safe, and several studies suggest that it is associated with improved fetal neurodevelopment and the prevention of the increase of both thyroglobulin levels and thyroid volume. Additionally, it appears to improve TSH, despite having no effect on the concentration of total and free thyroid hormones. Conclusions: Inadequate iodine intake is deleterious to maternal thyroid function and fetal neurodevelopment. Supplementation during pregnancy seems to prevent the functional deterioration of the thyroid. However, there are few randomized clinical trials and the evidence available is not always consistent, therefore more research on this topic is needed.

Palavras-chave : Iodine; Thyroid Gland; Thyroid Function; Pregnancy.

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