Sufficient iodine intake during pregnancy: just do it

Surgical Case Volume has an Impact on Outcomes for Patients with Lateral Neck Disease in Thyroid Cancer

BACKGROUND

This study aimed to assess whether surgical case volume for lateral neck dissection has an impact on the survival of patients who have well-differentiated thyroid cancer (WDTC) with lateral cervical node metastases. The authors used a population-based cohort study design.

METHODS

The study cohort consisted of WDTC patients in Ontario Canada who underwent thyroidectomy and lateral neck dissection. These patients were identified using both hospital- and surgeon-level administrative data between 1993 and 2017 (n = 1832). Surgeon and hospital volumes were calculated based on the number of cases managed in the year before the procedure by the physician and at the institution managing each case, respectively, and divided into tertiles. Multilevel Cox regression models were used to estimate the effect of volume on disease-free survival (DFS).

RESULTS

A crude model without patient or treatment characteristics demonstrated that DFS was associated with both higher surgeon volume tertiles (p < 0.01) and higher hospital volume tertiles (p < 0.01). After control for clustering, patient/treatment covariates, and hospital volume, the lowest surgeon volume tertile (range, 0-20/year; mean, 6.5/year) remained an independent statistically significant negative predictor of DFS (hazard ratio, 1.71; 95 % confidence interval, 1.22-2.4; p < 0.01).

CONCLUSION

Surgeon lateral neck dissection case volume is a predictor of better DFS for thyroid cancer patients, with the lowest surgeon volume tertile (<20 neck dissections per year) demonstrating poorer DFS.

Maternal Urinary Iodine Concentration and Pregnancy Outcomes in Euthyroid Pregnant Women: a Systematic Review and Meta-analysis

Iodine is an essential macronutrient for feto-maternal growth and development. Emerging evidence suggests that maternal iodine deficiency during pregnancy is potentially associated with both maternal and fetal adverse outcomes. The aim of this systematic review and meta-analysis was to investigate the association between maternal iodine status in euthyroid pregnant women and adverse pregnancy outcomes. A comprehensive literature search was performed in PubMed, Web of Science and Scopus up to October 2019 for retrieving related published articles in English. World Health Organization maternal median urinary iodine concentration (UIC) classification was used as follows: median UIC of less than 100, 100-149, 150-249, and more than 250 μg/L, for moderate-to-severe iodine deficiency, mild iodine deficiency, iodine adequate and more than adequate-to-excessive iodine, respectively. The primary outcomes of interest in this meta-analysis were the pooled prevalence and pooled odds ratio of the preterm birth, low birth weight (LBW), and one composite outcome of hypertensive disorders of pregnancy comprising pregnancy hypertension and preeclampsia. The secondary outcome was pooled mean of neonatal characteristics including birth weight, head circumference, Apgar score, and gestational age at birth. A total of 6 studies involving 7698 participants were included in this meta-analysis. The pooled prevalence of preterm birth, LBW, and hypertensive disorders of pregnancy were not statistically significantly different in the four groups of UIC levels. The pooled prevalence of preterm birth was 0.05, 0.04, 0.04, and 0.03 in UIC < 100, 100-149, 150-249, and > 250 μg/L, respectively. No evidence of an association was observed among the odds of preterm birth, LBW, and hypertensive disorders of pregnancy in euthyroid pregnant women with UIC between 100 and 149, 150-249, and > 250 μg/L compared with UCI < 100 μg/L. Likewise, there were not any statistical significant differences between the neonatal characteristics in different UIC groups. The results remained unchanged after subgroup analysis based on UIC less than 150 μg/L as abnormal UIC level. The present meta-analysis showed that the UIC of euthyroid pregnant women is not generally associated with the pregnancy outcomes and it per se is an insufficient indicator for prediction of pregnancy complications. The results of this study are important for reproductive healthcare providers and policymakers in providing appropriate healthcare service for pregnant women. However, further studies are needed to confirm these findings.

The placenta as a window to the brain: A review on the role of placental markers in prenatal programming of neurodevelopment

BACKGROUND

During development, the placenta can be said to be the most important organ, however, the most poorly researched. There is currently a broader understanding of how specific insults during development affect the fetal brain, and also the importance of placental signaling in neurodevelopmental programming. Epigenetic responses to maternal and fetal signals are an obvious candidate for transforming early life inputs into long-term programmatic outcomes. As a mediator of maternal and environmental signals to the developing fetus, epigenetic processes within the placenta are particularly powerful such that alterations of placental gene expression, downstream function, and signalling during foetal development have the potential for dramatic changes in developmental programming.

SUMMARY

In this article, we reviewed emerging evidence for a placental role in prenatal neurodevelopmental programming with a specific focus on nutrient and prenatal stress signals integration into chromatin changes; this new understanding, we hope will provide the means for lowering developmentally based disorder risk, and new therapeutic targets for treatment in adulthood.

KEY MESSAGES

Based on this review, the placenta is a potent micro-environmental player in neurodevelopment as it orchestrates a series of complex maternal-foetal interactions. Maternal insults to this microenvironment will impair these processes and disrupt foetal brain development resulting in the prenatal programming of neurodevelopmental disorders. These findings should inspire advance animal model and human research drive to appraise gene-environment impacts during pregnancy that will target the developmental cause of adult-onset mental disorders.

Influence of maternal thyroid hormones during gestation on fetal brain development

Thyroid hormones (THs) play an obligatory role in many fundamental processes underlying brain development and maturation. The developing embryo/fetus is dependent on maternal supply of TH. The fetal thyroid gland does not commence TH synthesis until mid gestation, and the adverse consequences of severe maternal TH deficiency on offspring neurodevelopment are well established. Recent evidence suggests that even more moderate forms of maternal thyroid dysfunction, particularly during early gestation, may have a long-lasting influence on child cognitive development and risk of neurodevelopmental disorders. Moreover, these observed alterations appear to be largely irreversible after birth. It is, therefore, important to gain a better understanding of the role of maternal thyroid dysfunction on offspring neurodevelopment in terms of the nature, magnitude, time-specificity, and context-specificity of its effects. With respect to the issue of context specificity, it is possible that maternal stress and stress-related biological processes during pregnancy may modulate maternal thyroid function. The possibility of an interaction between the thyroid and stress systems in the context of fetal brain development has, however, not been addressed to date. We begin this review with a brief overview of TH biology during pregnancy and a summary of the literature on its effect on the developing brain. Next, we consider and discuss whether and how processes related to maternal stress and stress biology may interact with and modify the effects of maternal thyroid function on offspring brain development. We synthesize several research areas and identify important knowledge gaps that may warrant further study. The scientific and public health relevance of this review relates to achieving a better understanding of the timing, mechanisms and contexts of thyroid programing of brain development, with implications for early identification of risk, primary prevention and intervention.

An evo-devo approach to thyroid hormones in cerebral and cerebellar cortical development: etiological implications for autism

The morphological alterations of cortical lamination observed in mouse models of developmental hypothyroidism prompted the recognition that these experimental changes resembled the brain lesions of children with autism; this led to recent studies showing that maternal thyroid hormone deficiency increases fourfold the risk of autism spectrum disorders (ASD), offering for the first time the possibility of prevention of some forms of ASD. For ethical reasons, the role of thyroid hormones on brain development is currently studied using animal models, usually mice and rats. Although mammals have in common many basic developmental principles regulating brain development, as well as fundamental basic mechanisms that are controlled by similar metabolic pathway activated genes, there are also important differences. For instance, the rodent cerebral cortex is basically a primary cortex, whereas the primary sensory areas in humans account for a very small surface in the cerebral cortex when compared to the associative and frontal areas that are more extensive. Associative and frontal areas in humans are involved in many neurological disorders, including ASD, attention deficit-hyperactive disorder, and dyslexia, among others. Therefore, an evo-devo approach to neocortical evolution among species is fundamental to understand not only the role of thyroid hormones and environmental thyroid disruptors on evolution, development, and organization of the cerebral cortex in mammals but also their role in neurological diseases associated to thyroid dysfunction.

Urgent global opportunities to prevent birth defects

Birth defects are an urgent global health priority. They affect millions of births worldwide. But their prevalence and impact are largely under-ascertained, particularly in middle- and low-income countries. Fortunately, a large proportion of birth defects can be prevented. This review examines the global prevalence and primary prevention methods for major preventable birth defects: congenital rubella syndrome, folic acid-preventable spina bifida and anencephaly, fetal alcohol syndrome, Down syndrome, rhesus hemolytic disease of the fetus and the newborn; and those associated with maternal diabetes, and maternal exposure to valproic acid or iodine deficiency during pregnancy. Challenges to prevention efforts are reviewed. The aim of this review is to bring to the forefront the urgency of birth defects prevention, surveillance, and prenatal screening and counseling; and to help public health practitioners develop population-based birth defects surveillance and prevention programs, and policy-makers to develop and implement science-based public health policies.

Thyroid disease in pregnancy: (Women's Health Series)

Pregnancy is a state of many hormonal changes that can make interpretation of thyroid function tests difficult. Measuring trimester-specific reference values of thyrotropin and free thyroxine is recommended. Because overt maternal hypothyroidism negatively affects the fetus, timely recognition and treatment are important. Women taking levothyroxine prepregnancy require a ≤50% dose increase during pregnancy. Hyperthyroidism can result from excessive human chorionic gonadotropin or Graves disease. Radioactive scanning should be avoided during pregnancy. Antithyroidal drug therapy should consist of propylthiouracil during the first trimester and methimazole thereafter. If indicated, beta blockers can be administered under obstetrical supervision. Iodine deficiency is a known goitrogen and stimulus for thyroid nodular growth. Thyroid nodules may enlarge, but the incidence of thyroid cancer is not increased during pregnancy. Suspicious nodules should be biopsied and, if necessary, removed during the second trimester; otherwise, follow-up can safely be conducted postpartum. Thyroid-stimulating hormone suppression for any preexisting thyroid cancer or suspicious nodules should achieve free or total T4 in the upper normal range for pregnancy. Postpartum thyroiditis occurs more frequently in antithyroid peroxidase-positive women, who should be screened by measuring serum thyrotropin at 6 to 12 weeks' gestation and at 3 and 6 months postpartum.