Excessive Prenatal Supplementation of Iodine and Fetal Goiter: Report of Two Cases Using Three-dimensional Ultrasound and Magnetic Resonance Imaging

Fetal thyroid complications in pregnancy are uncommon, and are commonly related to the passage of substances through the placenta. The excessive iodine intake during the pregnancy is a well-known mechanism of fetal thyroid enlargement or goiter, and invasive procedures have been proposed for the treatment of fetal thyroid pathologies. In the present report, we demonstrate two cases from different centers of prenatal diagnosis of fetal thyroid enlargement and/or goiter in three fetuses (one pair of twins, wherein both fetuses were affected, and one singleton pregnancy). The anamnesis revealed the ingestion of iodine by the patients, prescribed from inadequate vitamin supplementation. In both cases, the cessation of iodine supplement intake resulted in a marked reduction of the volume of the fetal thyroid glands, demonstrating that conservative treatment may be an option in those cases. Also, clinicians must be aware that patients may be exposed to harmful dosages or substances during pregnancy.

Excessive Iodine Induces Thyroid Follicular Epithelial Cells Apoptosis by Activating HIF-1α-mediated Hypoxia Pathway in Hashimoto Thyroiditis

Purpose Hashimoto thyroiditis (HT) is considered the most common autoimmune thyroid disease. A growing body of evidence suggests that HT incidence correlates with excessive iodine intake. We should probe the effects of excessive iodine intake in HT development and its possible mechanism. Methods The study recruited 20 patients: 10 with HT and 10 with nodular goiter. We detected the expression of an apoptosis-related protein caspase-3 by immunohistochemistry. In vitro study, we explored the proliferation and apoptosis status in thyroid follicular cells (TFCs) stimulated at different iodine concentrations by MTT and flow cytometry. Then we performed RNA sequence analysis of Nthy-ori3-1 cells treated for 48h with different KI concentrations to probe the underlying mechanism. Finally, we used RT-PCR to verify its results. Results We identified apoptosis in thyroid tissue obtained from HT patients coincides with the increase of caspase-3 levels. In vitro study, iodine suppressed proliferation of TFCs and promoted TFCs apoptosis in a dose-dependent manner. RNA sequence results showed that high concentration of iodine activate the hypoxia-inducible factor-1α (HIF-1α)-mediated hypoxia pathway coincide with the upregulation of N-myc downregulated gene-1 (NDRG1) expression. Conclusions Our study confirmed that excessive iodine adsorption activates the HIF-1α-mediated hypoxia pathway to promote apoptosis of TFCs, which may be an important risk factor contributing to HT development.

Establishment of an iodine model for prevention of iodine-excess-induced thyroid dysfunction in pregnant women

This study aims to explore the relationship between the iodine status and thyroid dysfunction (TD) in pregnant women and establish a model to guide them to prevent excessive iodine intake. A total of 515 pregnant women were enrolled in the study. Urinary iodine concentration (UIC), thyroid hormones, and thyroid autoantibodies were measured, and then a logistic regression model was established. The median UIC of pregnant women was 174 ± 120 μg/L. Multivariate logistic regression analysis indicated that multivitamin supplements containing iodine and frequent seafood consumption were risk factors for excessive iodine (UIC ≥500 μg/L). Besides, excessive iodine was a risk factor for TD. Iodine excess was associated with a high prevalence of TD in pregnant women, especially TPOAb-positive women (P < 0.05). A logistic regression model based on potential risk factors was established to predict the risk of excessive iodine intake among pregnant women and provide guidance to minimize the risk of excessive iodine intake, thus reducing the risk of TD.

Iodine, Thyroglobulin and Thyroid Gland

Iodine is essential in the biosynthesis of thyroid hormones that affect metabolic processes in the organism from the prenatal state to the elderly. The immediate indicator of iodine intake is the concentration of iodine in urine, but the indicator of iodine intake in the longer term of several months is thyroglobulin (Tg). Tg negatively correlated with increasing intake of iodine in population that do not suffer from thyroid disease, while a more than adequate to excessive iodine intake leads to an increase in Tg. The dependence of Tg on iodine can be described by a U-shaped curve. Thyroglobulin in serum is elevated in thyroid disease mainly in hyperthyroidism (diagnosis E05 of WHO ICD-10 codes) and in goiter (diagnosis E04 of WHO ICD-10 codes). Tg values decrease below 20 µg/l after effective treatment of patients with thyroid disease. Thyroglobulin may thus be an indicator of thyroid stabilization and the success of the thyroid gland treatment.

Knowledge and awareness of iodine intake - survey among Croatian women of reproductive age

Introduction: Appropriate iodine intake is important for the entire population, especially in fertile women due to decisive role of thyroid hormones in normal foetal brain development. The aim of this study was to investigate knowledge on iodine role among Croatian women of reproductive age. Materials and methods: The survey was conducted among 378 women of reproductive age during May-September 2018. Data on age, education level, salt intake habits, knowledge of the iodine role and possible presence of thyroid disease were collected and results were presented as numbers or percentage of total number of participants. Comparison between groups was performed by Chi square test. Results: Of 378 participants, 178 reported to be familiar with the iodine role in the body (P = 0.115). Significantly higher proportion of the younger woman and woman with lower degree of education weren’t familiar with the iodine role (P < 0.001). More woman were introduced to consequences of insufficient than to excessive iodine intake (273 vs 213; P < 0.001). In addition, participants mainly weren’t familiar with obligation of salt iodination (P < 0.001). Presence of thyroid disease was recorded in 75 subjects with higher prevalence in subjects 36-49 years (P < 0.001). Presence of thyroid disease was not associated with knowledge on iodine role on health. Conclusion: Women of reproductive age are not completely aware of the consequences of excessive iodine intake. Thus, further education focusing on more sensitive groups such as woman of younger age should be considered in order to preserve their and their children’s health.