Thyroïde et environnement

Correlation Between Drinking Water and Iodine Status: a Systematic Review and Meta-analysis

Iodine is a micronutrient essential for maintaining normal body functioning, and the consumption depends on the distribution in the environment, and insufficient or excessive intake results in thyroid dysfunction. The purpose of this review was to evaluate the correlation between iodine concentration in drinking water and the iodine status of the population. The systematic review was conducted following the PRISMA guidelines and was registered at the International Prospective Register of Ongoing Systematic Reviews (CRD42019128308). A literature search was conducted using MEDLINE/PUBMED (National Library of Medicine), LILACS (Latin-American and Caribbean Literature on Health Sciences), and Cochrane Library, June 2021. The quality of the studies was assessed by a checklist for cross-sectional studies developed by Joanna Briggs Institute. The initial search identified 121 articles, out of which ten were included in this systematic review, and five were included in the meta-analysis. Among the articles listed, six adopted cutoff points to classify the iodine content in the drinking water. The study identified median iodine concentration in drinking water from 2.2 to 617.8 μg/L and the correlation between iodine concentration in drinking water and urinary iodine concentration was 0.92, according to meta-analysis. Furthermore, the iodine status was correlated to the iodine content in water. The determination of a cutoff point can contribute to the implementation of iodine consumption control measures.

Epidemiological, Clinical, Ultrasonographic and Cytological Characteristics of Thyroid Nodules in an Afro-Caribbean Population: A Series of 420 Patients

Simple Summary

This study describes the epidemiological, clinical and ultrasound characteristics of malignancy in thyroid nodules and evaluates the value of cytology in the diagnosis of malignancy in an Afro-Caribbean population. Our results revealed that none of the standard ultrasound criteria of malignancy were significantly predictive of cancer, but hypoechogenicity and central vascularity were frequently found in malignant nodules. These results could increase awareness and guide practitioners in their diagnostic approach and management of thyroid nodules in Afro-Caribbean populations. Bethesda system-based cytology revealed low sensitivity in analyzing the risk of malignancy in this population. The high prevalence of papillary microcarcinomas may explain the inconclusive ultrasound and cytological results.

Abstract

The incidence of thyroid cancer is increasing worldwide. The aim of this study is to describe the epidemiological, clinical and ultrasound characteristics of malignancy in thyroid nodules and to evaluate the predictive value of the Bethesda system for thyroid cytology in the diagnosis of malignancy in an Afro-Caribbean population. We conducted a retrospective study in Martinique involving 420 patients with a diagnosis of thyroid nodules between 2011 and 2014. Of the 192/420 (45.7%) patients operated on for thyroid nodules, 9% had thyroid cancer. All patients with thyroid cancer were obese women with a mean age of 50 years. The final histological examination revealed papillary microcarcinomas in 61% of cases and papillary carcinomas in 39% of cases. Thyroid cytology alone had a low sensitivity (22.2%) and positive predictive value (15.4%) for the diagnosis of malignancy, with a good specificity (91.1%) and negative predictive value (94.2%). None of the standard ultrasound criteria of malignancy were significantly predictive of cancer, but hypoechogenicity and central vascularity were frequently found in malignant nodules. These epidemiological, clinical and ultrasound results could increase awareness and guide practitioners in their diagnostic approach and management of thyroid nodules in an Afro-Caribbean population. Bethesda system-based cytology revealed lower sensitivity in analyzing the risk of malignancy in this population. The high prevalence of papillary microcarcinomas may explain the inconclusive ultrasound and cytological results.

Endocrine disruptors and thyroid autoimmunity

Many papers evaluated the effect of the environmental, or occupational endocrine disruptors (ED), on the thyroid gland, that can lead to thyroid autoimmunity. A higher prevalence of autoimmune thyroid diseases (AITD) was observed in people living in polluted areas near to petrochemical plants, and in petrochemical workers, but also in area contaminated with organochlorine pesticides, or with polychlorinated biphenyls, or near aluminum foundries. The exposure to Hg in chloralkali workers, or in swordfish consumers has been also found to increase AITD prevalence. Vanadium has been shown to increase the inflammatory response of thyrocytes. A beneficial effect of omega-3 fatty acids, and of myo-inositol and selenomethionine have been shown to counteract the appearance of AITD in subjects exposed to environmental or occupational ED. More large studies are needed to investigate the potential roles of ED in the induction of AITD, and of agents or habits that are able to prevent them.

Epidemiology of Childhood Hyperthyroidism in France: A Nationwide Population-Based Study

CONTEXT

Hyperthyroidism affects all age groups, but epidemiological data for children are scarce.

OBJECTIVE

To perform a nationwide epidemiological survey of hyperthyroidism in children and adolescents.

DESIGN

A cross-sectional descriptive study.

SETTING

Identification of entries corresponding to reimbursements for antithyroid drugs in the French national insurance database.

PARTICIPANTS

All cases of childhood hyperthyroidism (6 months to 17 years of age) in 2015.

MAIN OUTCOME MEASURES

National incidence rate estimated with a nonlinear Poisson model and spatial distribution of cases.

RESULTS

A total of 670 cases of childhood hyperthyroidism were identified. Twenty patients (3%) had associated autoimmune or genetic disease, with type 1 diabetes and Down syndrome the most frequent. The annual incidence for 2015 was 4.58/100,000 person-years (95% CI 3.00 to 6.99/100,000). Incidence increased with age, in both sexes. This increase accelerated after the age of 8 in girls and 10 in boys and was stronger in girls. About 10% of patients were affected before the age of 5 years (sex ratio 1.43). There was an interaction between age and sex, the effect of being female increasing with age: girls were 3.2 times more likely to be affected than boys in the 10 to 14 years age group and 5.7 times more likely to be affected in the 15 to 17 years age group. No conclusions about spatial pattern emerged.

CONCLUSION

These findings shed light on the incidence of hyperthyroidism and the impact of sex on this incidence during childhood and adolescence. The observed incidence was higher than expected from the results published for earlier studies in Northern European countries.

The effect of maternal exposure to endocrine disrupting chemicals on fetal and neonatal development: A review on the major concerns

There is a widespread exposure of general population, including pregnant women and developing fetuses, to the endocrine disrupting chemicals (EDCs). These chemicals have been reported to be present in urine, blood serum, breast milk, and amniotic fluid. Endocrine disruptions induced by environmental toxicants have placed a heavy burden on society, since environmental exposures during critical periods of development can permanently reprogram normal physiological responses, thereby increasing susceptibility to disease later in life-a process known as developmental reprogramming. During development, organogenesis and tissue differentiation occur through a continuous series of tightly-regulated and precisely-timed molecular, biochemical, and cellular events. Humans may encounter EDCs daily and during all stages of life, from conception and fetal development through adulthood and senescence. Nevertheless, prenatal and early postnatal windows are the most critical for proper development, due to rapid changes in system growth. Although there are still gaps in our knowledge, currently available data support the urgent need for health and environmental policies aimed at protecting the public and, in particular, the developing fetus and women of reproductive age. Birth Defects Research (Part C) 108:224-242, 2016. © 2016 Wiley Periodicals, Inc.