Abstract

NOBREGA, Joana Ramos  and  CEBOLAIS, Ana. A case of hyperthyroidism in pregnancy: excessive iodine supplementation?. Rev Port Med Geral Fam [online]. 2019, vol.35, n.3, pp.239-243. ISSN 2182-5173.  https://doi.org/10.32385/rpmgf.v35i3.12009.

In Portugal, iodine supplementation is recommended for all women in pre-conception, during pregnancy and exclusive breastfeeding in the dose of 150 to 200µg/day. After this recommendation, we found an increase of the incidence of autoimmune thyroiditis, both hypo and of hyperthyroidism, by iodine-induced thyrotoxicosis in people with pre-existing multinodular goiter. This article reports a case of hyperthyroidism in a pregnant woman, aiming to describe the difficulty on diagnosis and to alert to the importance of take this situation in mind, especially in the context of current recommendations for iodine supplementation in pregnancy. The case reports a twin pregnancy in a 38-year-old woman with family history of multinodular goiter. She was supplemented with iodine through two supplements: the one prescribed by the doctor and another one in a multivitamin pill over-the-counter. The total dose was much higher than recommended, leading to a iatrogenic hyperthyroidism. There’s no consensus about screening of thyroid dysfunction before supplementation, although some experts defend to ask for preconceptional thyroid-stimulating hormone (TSH), especially in woman at risk, like age over 30 years, personal or family history of goiter or other thyroid disease. Multiple gestation and iatrogenic events are the leading causes of hyperthyroidism in pregnancy. It’s crucial to know the various sources of iodine and the total amount ingested by pregnants, especially if there is risk for thyroid disease. Many pregnants are taking supplements over-the-counter, with the false-perception of security, because it’s not a medication. In this case, there was no previous record of TSH in pre-conception or during pregnancy and total iodine supplementation was excessive, justifying the events, and calling for increased attention for both factors.

Keywords : Iodine; Pregnancy; Thyroid; Thyroid dysfunction.

        · abstract in Portuguese     · text in Portuguese     · Portuguese ( pdf )