Thyroid autoimmunity in the current iodine environment

The relationship between the gut microbiota and thyroid disorders

Disorders of the thyroid gland are common, more prevalent in women than in men, and range from inflammatory to neoplastic lesions. Autoimmune thyroid diseases (AITD) affect 2-5% of the population, while thyroid cancer is the most frequent endocrine malignancy. Treatment for AITD is still restricted to management rather than prevention or cure. Progress has been made in identifying genetic variants that predispose to AITD and thyroid cancer, but the increasing prevalence of all thyroid disorders indicates that factors other than genes are involved. The gut microbiota, which begins to develop before birth, is highly sensitive to diet and the environment, providing a potential mechanism for non-communicable diseases to become communicable. Its functions extend beyond maintenance of gut integrity: the gut microbiota regulates the immune system, contributes to thyroid hormone metabolism and can generate or catabolize carcinogens, all of which are relevant to AITD and thyroid cancer. Observational and interventional studies in animal models support a role for the gut microbiota in AITD, which has been confirmed in some reports from human cohorts, although considerable geographic variation is apparent. Reports of a role for the microbiota in thyroid cancer are more limited, but evidence supports a relationship between gut dysbiosis and thyroid cancer.

NLRP3 inflammasome and its role in autoimmune diseases: A promising therapeutic target

The NOD-like receptor protein 3 (NLRP3) inflammasome is a protein complex that regulates innate immune responses by activating caspase-1 and the inflammatory cytokines IL-1β and IL-18. Numerous studies have highlighted its crucial role in the pathogenesis and development of inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus, autoimmune thyroid diseases, and other autoimmune diseases. Therefore, investigating the underlying mechanisms of NLRP3 in disease and targeted drug therapies holds clinical significance. This review summarizes the structure, assembly, and activation mechanisms of the NLRP3 inflammasome, focusing on its role and involvement in various autoimmune diseases. This review also identifies studies where the involvement of the NLRP3 inflammasome in the disease mechanism within the same disease appears contradictory, as well as differences in NLRP3-related gene polymorphisms among different ethnic groups. Additionally, the latest therapeutic advances in targeting the NLRP3 inflammasome for autoimmune diseases are outlined, and novel clinical perspectives are discussed. Conclusively, this review provides a consolidated source of information on the NLRP3 inflammasome and may guide future research efforts that have the potential to positively impact patient outcomes.

Urinary iodine concentration and its associations with thyroid function in pregnant women of Shanghai

Objective

To assess the iodine status and its associations with thyroid function in pregnant women of Shanghai.

Methods

In this cross-sectional study, a total of 562 pregnant women were enrolled from January to December 2021. Both serum thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), thyroid peroxidase antibody (TPOAB), thyroglobulin antibody (TGAB), and urinary iodine concentration (UIC) were detected. Participants were divided into four groups based on their UIC values. Correlation analysis was used to investigate the association between UIC and thyroid function-associated parameters.

Results

The median UIC of the pregnant women studied was 158.25µg/L (interquartile range [IQR] 90.15, 245.65µg/L). Among all the subjects, 45.55% had iodine deficiency according to the World Health Organization (WHO) criteria, and 15.65% had thyroid autoimmunity. FT3, FT4, TSH, TPOAB and TGAB levels were not different among different UIC groups (P > 0.05). UIC and TSH were negatively correlated (r=-0.127, p=0.043) in UIC<150 µg/L group. In the group with UIC 250- 499 µg/L, UIC was positively correlated with total T4 (TT4), total T3 (TT3) and TPOAB (r= 0.228, p=0.022, r=0.208, p= 0.039, r=0.190, p=0.042, respectively). A negative correlation between UIC and TPOAB values was observed in TPOAB-positive (+) pregnant women (r=-0.384, p=0.012). The prevalence of isolated hypothyroxinemia in UIC<150 µg/L group was significantly higher than that of other groups(p=0.033). The relationship between the prevalence of thyroid diseases and UIC embodied a U-shaped curve.

Conclusion

Pregnant women on Chongming Island of Shanghai were iodine sufficient during the second trimester, but iodine deficiency was still prevalent. Both low and high gestational iodine status was related to thyroid function and autoimmunity. Optimal iodine nutrition status during gestation was important.

The role of transforming growth factor beta in thyroid autoimmunity: current knowledge and future perspectives

The complex mechanisms, which are related to the pathophysiology and the development of autoimmune thyroid diseases, involve transforming growth factor beta (TGF-β) and its interplay with the immune system. The aim of this review is to examine the role of TGF-β regarding thyroid autoimmunity and explore the potent role of this molecule either as a diagnostic or prognostic marker or a therapeutic target regarding autoimmune thyroid diseases. TGF-β is clearly a master regulator of the immune response, exerting either inhibitory or facilitatory effects on cells of the immune system. Thus, this molecule is involved in the pathogenesis and development of autoimmune thyroid diseases. Recent research has revealed the involvement of TGF-β in the pathophysiology of autoimmune thyroid diseases. The role of TGF-β in the development of autoimmune thyroid diseases varies, depending on its concentrations, the type of the activated TGF-β signalling pathway, the genetic predisposition of the patient and the pathophysiologic stage of the disease. TGF-β could emerge as a useful diagnostic or prognostic marker for the evolution of thyroid autoimmunity. Promising perspectives for the effective therapeutic use of TGF-β regarding thyroid autoimmunity exist. The main treatment approaches incorporate either enhancement of the immunosuppressive role of TGF-β or inhibition of its facilitatory role in the autoimmune thyroid diseases. Further research towards deeper understanding of TGF-β physiology and clinical application of its possible therapeutic role regarding thyroid autoimmunity is needed.

Effect of Moderate-to-Severe Iodine Deficiency in Early Pregnancy on Subclinical Hypothyroidism: A Longitudinal Study in an Iodine-Sufficient Region in China

Objective

To investigate iodine status among pregnant women in an iodine-sufficient region in China after the implementation of revised universal salt iodization (USI) standards in 2012 and assess the association between urinary iodine concentrations (UIC) in early pregnancy and the incidence of subclinical hypothyroidism (SCH) in euthyroid women negative for antithyroid Ab during different trimesters.

Methods

We measured the iodine status of 1,264 pregnant women, and performed follow-up assessment of thyroid function at 20 and 30 weeks of gestation among a cohort of 250 euthyroid women. We assessed the association of UIC in the 1st trimester with the incidence of SCH in subsequent trimesters. UIC and serum free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb) were measured.

Results

The median UIC was 135.95 μg/L among 1,264 women. Serum FT4 level was significantly higher in the group of UIC 150 to 249 μg/L compared with other UIC groups (P &lt; 0.001). TSH was significantly higher in the UIC more than or equal to 250 μg/L group than the UIC 150 to 249 g/L group (P = 0.043). Of the 250 euthyroid women negative for antithyroid Ab (TSH value of 2.5–3.55 mU/L) in the 1st trimester, pregnant women with UIC lower than 100 μg/L in the 1st trimester exhibited a significantly increased risk of SCH (odds ratio [OR] = 2.47; 95% confidence interval [CI] = 1.22–5.71; P = 0.012, according to the Chinese Medical Association criteria; OR = 5.22, 95% CI = 1.73–6.09, P = 0.004, according to ATA criteria) during the latter half of pregnancy compared with the UIC 150 to 249 μg/L group.

Conclusion

Moderate-to-severe iodine deficiency (UIC lower than 100 μg/L) in the 1st trimester was associated with a significantly higher risk of SCH during the 2nd or 3rd trimesters among euthyroid pregnant women who had negative for antithyroid Ab. Women with SCH during pregnancy require regular UIC tests to maintain appropriate iodine status.

Distributions of serum thyroid-stimulating hormone in 2020 thyroid disease-free adults from areas with different iodine levels: a cross-sectional survey in China

PURPOSE

The aim of the present study was to describe the distributions of serum thyroid- stimulating hormone (TSH) levels in thyroid disease-free adults from areas with different iodine levels in China. Meanwhile, we aimed to evaluate the influence of age and gender on the distribution of TSH, assess the relationship between concentrations of TSH and free thyroxine (FT₄), and analyze the factors that may affect TSH levels.

METHODS

2020 adults were included from April 2016 to June 2019. Urinary iodine concentration, serum iodine concentration, serum TSH, FT₄, free triiodothyronine, thyroid peroxidase antibodies and thyroglobulin antibodies were measured, and thyroid ultrasonography was performed.

RESULTS

The median of TSH in iodine-fortification areas (IFA), iodine-adequate areas (IAA), iodine-excessive areas (IEA) were 2.32, 2.11 and 2.34 mIU/L, respectively. Serum TSH concentrations were significantly higher in IFA and IEA than that in IAA (p = 0.005 and < 0.0001). The TSH values of most adults were distributed within the range of 1.01-3.00 mIU/L with the same trend in three groups. In our study, TSH levels did not change with age, and the TSH level of females was higher than that of males (p < 0.0001). There was a negative correlation between FT₄ and TSH in IAA (r = - 0.160, p < 0.0001) and IEA (r = - 0.177, p < 0.0001), but there was no correlation between FT₄ and TSH in IFA (r = - 0.046, p = 0.370). BMI, smoking status, education levels, and marital status were associated with TSH.

CONCLUSION

Our study provides a basis for establishing the reference intervals of TSH in different iodine level areas.

Immunological Drivers in Graves' Disease: NK Cells as a Master Switcher

Graves' disease (GD) is a common autoimmune cause of hyperthyroidism, which is eventually related to the generation of IgG antibodies stimulating the thyrotropin receptor. Clinical manifestations of the disease reflect hyperstimulation of the gland, causing thyrocyte hyperplasia (goiter) and excessive thyroid hormone synthesis (hyperthyroidism). The above clinical manifestations are preceded by still partially unraveled pathogenic actions governed by the induction of aberrant phenotype/functions of immune cells. In this review article we investigated the potential contribution of natural killer (NK) cells, based on literature analysis, to discuss the bidirectional interplay with thyroid hormones (TH) in GD progression. We analyzed cellular and molecular NK-cell associated mechanisms potentially impacting on GD, in a view of identification of the main NK-cell subset with highest immunoregulatory role.

Reference Range and Sociodemographic Characteristics of TSH among Reproductive Age Women in Rural China

Appropriate reference range of thyroid-stimulating hormone (TSH) is important to interpreting the results of thyroid functional tests. However, the reference range and sociodemographic characteristics of TSH based on large-scale studies are yet to be declared in rural China. To clarify reference range and sociodemographic characteristics of TSH in reproductive age of women from rural China. A nationwide population-based study was conducted as The National Free Preconception Health Examination Project (NFPHEP). Nearly 400,000 (n = 392,659) of Chinese rural women aged 15-55 years were randomly recruited. Predetermined strict exclusion criteria made a number of 359,895 as the reference population. Serum TSH was evaluated with enzyme-linked immunosorbent assay (ELISA). The reference range of TSH on overall and reference population was 0.39-5.20 and 0.39-5.13 uIU/ml (2.5th-97.5th percentiles), respectively. In the reference population, the range (2.5th to 97.5th percentile) of serum TSH in different age groups was 0.40-5.03 uIU/ml, 0.39-5.15 uIU/ml, 0.37-6.10 uIU/ml, and 0.44-7.03 uIU/ml, respectively. The mean TSH value in women aged 26-35 years was 2.26 uIU/ml, significantly lower than those aged 36-45 (p < 0.001). The mean TSH values for eastern, central, and western regions were 2.28 uIU/ml, 2.29 uIU/ml, and 2.24 uIU/ml respectively. The mean of serum TSH concentration was significantly higher in central region than that in western region (p ≤ 0.001). The TSH value 0.39-5.13 uIU/ml (2.5th-97.5th percentiles) was derived as a reference range of reproductive age women from rural China. We use the TSH ranges from reference population to diagnose hyperthyrotropinemia or hypothyroidism in different areas in China. The reference ranges for eastern, central, and western regions were 0.33-5.61 uIU/ml, 0.40-5.04 uIU/ml, and 0.40-4.98 uIU/ml (2.5th-97.5th percentiles) respectively. The value of serum TSH was associated with age, living region, smoking, drinking, educational level, and interpersonal tension, as well as life and economic pressure, but irrelevant to ethnicity or occupation.

Iodine Status in the Colombian Population and the Impact of Universal Salt Iodization: A Double-Edged Sword?

Iodine deficiency and iodine excess have severe consequences on human health and have been associated with the presence of goiter, hypothyroidism, hyperthyroidism, thyroid cancer, thyroid nodules and thyroid autoimmunity, poor mental health, and impaired intellectual development. Universal salt iodization programs have been considered one of the most cost-effective interventions for the prevention of iodine deficiency-associated disorders, as evidenced over time since the implementation of such programs. However, these efforts have also led to an excessive consumption of iodine in certain geographical regions, due to salt overuse. Consequently, the amount of iodine derived from salt intake exceeds the established limits required for achieving the right balance between salt consumption and health benefits and leads to undesirable health effects. In Colombia, the recommendations and standards for the production and commercialization of iodized salt are fully complied with. Nevertheless, there is a remarkable rate of iodine excess among the country's population, which, at least hypothetically, represents a higher risk for developing functional and structural disorders of the thyroid gland. This review analyzes universal salt iodization programs worldwide, particularly their impact on the thyroid gland and the results of the studies conducted in Colombia following the implementation of such strategy.

Excessive Iodine Promotes Pyroptosis of Thyroid Follicular Epithelial Cells in Hashimoto's Thyroiditis Through the ROS-NF-κB-NLRP3 Pathway

Hashimoto's thyroiditis (HT) is a common autoimmune thyroid disease. In recent years, increasing evidence has proven that the incidence of HT is associated with the excessive iodine intake of the body. In the present study, we measured the status of pyroptosis in thyroid tissues from patients with HT and the effects of excessive iodine on the pyroptosis in thyroid follicular cells (TFCs), in an attempt to illuminate the effects of iodine excess on the development of HT disease. Our results showed that increased pyroptosis occurred in the thyroid tissues of HT patients and that an increase in pyroptosis activity in TFCs was primed by excessive iodine in vitro. This process was mediated by reactive oxygen species (ROS) and activation of the NF-κB signaling pathway. In addition, excessive iodine caused NLRP3 inflammasome activation in TFCs, which promoted TFC pyroptosis. Moreover, the release of interleukin-1β (IL-1β) was closely linked to pyroptosis activation. Taken together, our results suggested that excessive iodine contributed to aberrant activation of pyroptosis in TFCs, which could be a pivotal predisposing factor for HT development.

Iodine intake and chronic autoimmune thyroiditis: a comparative study between coastal and mainland regions in Greece

INTRODUCTION

The purpose of this study was to evaluate the relationship between iodine intake and autoimmune thyroiditis in Chios, an island located in the North East Aegean Sea, in comparison to mainland regions in South Western Greece (SWG).

MATERIALS AND METHODS

Urine iodine concentration (UIC), thyroid function (serum TSH, thyroid autoantibodies: anti-TPO and anti-Tg), and thyroid U/S were assessed in 200 subjects (150 females and 50 males) from Chios and 322 subjects (255 females and 67 males) from several mainland regions in SWG. All participants were recruited from outpatient clinics and were diagnosed as euthyroid.

RESULTS

Median UIC in Chios was significantly higher compared to SWG (136.1 vs. 104.5 μg/L, p < 0.001), indicating that both regions are iodine sufficient according to World Health Organization (WHO) criteria. The prevalence of thyroid autoimmunity was 66.5% in Chios and 27% in SWG, significantly higher in females (46.7%) than in males (26.5%). Furthermore, individuals with increased levels of thyroid autoantibodies either anti-TPO or anti-Tg (TAbs) showed increased median UIC levels compared to those / subjects / patients with normal levels (126.7 vs. 108.95 μg/L, p < 0.001). Serum TSH mean values (mIU/L) were greater in females (mean = 2.1 ± 1.41) compared to males (mean = 1.82 ± 1.26) (p = 0.04) and decreased with age.

CONCLUSIONS

In conclusion, in the present study, we clearly indicate that increased thyroid autoimmunity is positively associated with increased iodine intake, as well as with the female gender. Moreover, iodine intake and thyroid autoimmunity appear to be significantly higher in a coastal region (Chios) than in mainland Greece (SWG). Additional environmental factors, apart from iodine, should be investigated in future studies. Mean TSH values were increased in females and decreased with age. The latter is probably due to the presence of autonomous goiter in older Greek populations, as a result of long-term status of iodine deficiency in the past.

Heart failure, micronutrient profile, and its connection with thyroid dysfunction and nutritional status

INTRODUCTION

Heart failure (HF) is a growing public health issue; its risk factors include inappropriate dietary intake of microelements such as iodine, selenium, zinc and iron, which may lead to thyroid dysfunction.

OBJECTIVE

This study aimed to assess the correlation among the functional class stages of patients with HF, iodine, selenium, iron and zinc levels with the presence of thyroid dysfunction.

METHODOLOGY

One hundred nine patients from the HF outpatient clinic of the Clinics Hospital of Ribeirão Preto whose blood and urine were collected for micronutrient analysis and laboratory tests were selected. The subjects' weight and height were also measured to calculate their BMI. First, a descriptive analysis of the data was made into tables, and then statistical analyses were done at a 5% significance level (p < 0.05).

RESULTS

Most patients whose data was analysed were elderly and overweight. Excess ioduria, serum selenium and zinc, erythrocyte zinc and deficiency in serum iron and erythrocyte selenium were observed. The prevalence of thyroid dysfunction was 8.3%. Multivariate logistic regression verified that thyroid dysfunction increases the chance of classification in functional class III or IV (p = 0.015; OR = 8.72) by 8.7 times; each year of age increases the chance by 4.6% of classification in functional class III or IV (p = 0.008; odds ratio [OR] = 1.05), and each unit of BMI increases the chance of classification in functional class III or IV by 9.2% (p = 0.028; OR = 1.09).

CONCLUSION

Patients with HF were deficient in serum iron and erythrocyte selenium. No connection was found between hypothyroidism and mineral deficiency, which seems to be related more to the severity of the disease than to the micronutrient nutritional profile.

Glycyrrhizin, a Direct HMGB1 Antagonist, Ameliorates Inflammatory Infiltration in a Model of Autoimmune Thyroiditis via Inhibition of TLR2-HMGB1 Signaling

BACKGROUND

High mobility group box-1 (HMGB1), a non-histone protein, plays an important role in autoimmune diseases. However, the significance of HMGB1 in the pathogenesis of autoimmune thyroiditis has not been reported. The purpose of this study was to explore whether HMGB1 participates in the pathogenesis of autoimmune thyroiditis, and whether glycyrrhizin (GL), a direct inhibitor of HMGB1, attenuates the severity of thyroid inflammatory infiltration in a murine model of autoimmune thyroiditis.

METHODS

A total of 80 male NOD.H-2^h4 mice were randomly divided into a control or iodine supplement (NaI) group at four weeks of age, and the control group was fed with regular water, whereas the NaI group was supplied with 0.005% sodium iodine water. Another 24 male NOD.H-2^h4 mice were also randomized into three groups (eight mice per group) as follows: control, NaI, and GL treatment after iodine supplementation (NaI + GL). The NOD.H-2^h4 mice were fed with 0.005% sodium iodide water for eight weeks to enhance autoimmune thyroiditis. After iodine treatment, the mice received intraperitoneal injections of GL for four weeks. The severity of lymphocytic infiltration in the thyroid gland was measured by histopathological studies. The serum levels of HMGB1, tumor necrosis factor alpha, interleukin (IL)-6, IL-1β, and thyroglobulin antibody titers were measured using an enzyme-linked immunosorbent assay. HMGB1 expression was measured by immunohistochemical staining and real-time polymerase chain reaction. TLR2, HMGB1, MyD88, and nuclear transcription factor κB were measured by Western blot.

RESULTS

The mRNA expression of HMGB1 was significantly higher at 8 and 16 weeks in the NaI group than it was in the control group. Serum levels of thyroglobulin antibodies, HMGB1, tumor necrosis factor alpha, IL-6, and IL-1β were significantly increased in the NaI group, but they were dramatically attenuated with GL injection. The prevalence of thyroiditis and the infiltration of lymphocytes were significantly decreased in the NaI + GL group. GL administration also significantly reduced the protein expression of TLR2, MyD88, HMGB1 and nuclear transcription factor κB in the thyroid gland and attenuated the severity of thyroiditis.

CONCLUSION

HMGB1 may play a crucial role in autoimmune thyroiditis by causing inflammatory infiltration, thus increasing the severity of autoimmune thyroiditis. GL effectively attenuated thyroiditis in the iodine-induced NOD.H-2^h4 mice via a molecular mechanism related to the inhibition of TLR2-HMGB1 signaling.

Population-Based National Prevalence of Thyroid Dysfunction in Spain and Associated Factors: Di@bet.es Study

BACKGROUND

The aim of this study was to investigate the national prevalence of thyroid dysfunction in Spain and its association with various clinical, environmental, and demographic variables.

METHODS

The study included 4554 subjects (42.4% men) with a mean age of 50 years (range 18-93 years), who were participants in a national, cross-sectional, population-based survey conducted in 2009-2010. Data gathered included clinical and demographic characteristics, physical examination, and blood sampling. Thyrotropin, free thyroxine, free triiodothyronine, and thyroid peroxidase antibody (TPOAb) concentrations were analyzed by electrochemiluminescence. Urinary iodine (UI) levels were measured in an isolated urine sample.

RESULTS

The prevalence of treated hypothyroidism, untreated subclinical hypothyroidism, and untreated clinical hypothyroidism was 4.2% [confidence interval (CI) 3.6-4.9%], 4.6% [CI 4.0-5.2%], and 0.3% [CI 0.1-0.5%], respectively. The prevalence of total hypothyroidism (including all fractions) was 9.1% [CI 8.2-10.0%]. The prevalence of total hyperthyroidism was 0.8% [CI 0.6-1.1]. A total of 7.5% [CI 6.7-8.3%] of the population tested positive for TPOAbs (≥50 IU/mL). In multivariate logistic regression models, TPOAbs were strongly associated with both hypothyroidism (p < 0.001) and hyperthyroidism (p = 0.005), whereas high UI levels (>200 μg/g creatinine) were associated with hypothyroidism (p < 0.001). The positive association between UI and hypothyroidism remained for both treated (p < 0.001) and untreated (p < 0.05) hypothyroidism, whereas it was especially significant for non-autoimmune (TPOAbs negative) forms (p < 0.001). At UI levels ≥200 μg/g, there was a positive correlation between UI and thyrotropin levels (β = 0.152, p < 0.001) and a negative correlation between UI and free triiodothyronine levels (β = -0.134, p = 0.001).

CONCLUSION

According to the data, a large proportion (10%) of the Spanish population has some evidence of thyroid dysfunction. High TPOAb concentrations were associated with both hypo- and hyperthyroidism, whereas high UI concentrations were associated with hypothyroidism.

Environmental Issues in Thyroid Diseases

Environmental factors are determinant for the appearance of autoimmune thyroid diseases (AITD) in susceptible subjects. Increased iodine intake, selenium, and vitamin D deficiency, exposure to radiation, from nuclear fallout or due to medical radiation, are environmental factors increasing AITD. Cigarette smoking is associated with Graves' disease and Graves' ophthalmopathy, while it decreases the risk of hypothyroidism and thyroid autoimmunity. Viral infections are important environmental factors in the pathogenesis of AITD, too, particularly human parvovirus B19 (EVB19) and hepatitis C virus. Among the many chemical contaminants, halogenated organochlorines and pesticides variably disrupt thyroid function. Polychlorinated biphenyls and their metabolites and polybrominated diethyl ethers bind to thyroid transport proteins, such as transthyretin, displace thyroxine, and disrupt thyroid function. Among drugs, interferon- and iodine-containing drugs have been associated with AITD. Moreover intestinal dysbiosis causes autoimmune thyroiditis. To reduce the risk to populations and also in each patient, it is necessary to comprehend the association between environmental agents and thyroid dysfunction.

Monitoring the prevalence of thyroid disorders in the adult population of Northeast Germany

BACKGROUND

Only a few studies like ours have investigated the effect of long-term stable iodine supply on thyroid disorders in a historically iodine-deficient population, but not with a long follow-up time of 10 years.

METHODS

Data were derived from two independent population-based cohorts of the Study of Health in Pomerania (SHIP-0 [1997-2001] and SHIP-TREND [2008-2012]) comprising 4308 and 4420 subjects, respectively. Diagnosed thyroid disorders were assessed. Thyroid gland dimensions were examined by ultrasound. Levels of serum thyrotropin (TSH) and autoantibodies to thyroperoxidase (anti-TPO Abs) were measured from blood samples.

RESULTS

Median urinary iodine excretion levels decreased from 123.0 μg/l to 112.0 μg/l (p = <0.001) between 2000 and 2010. The prevalence of known thyroid disorders increased from 7.6 % [CI 6.9-8.5] to 18.9 % [CI 17.6-20.1] and of thyroid medication use from 6.2 to 11.1 %. The prevalence of goiter decreased from 35.1 to 29.4 % (p = <0.001), while the prevalence of positive anti-TPO Abs decreased from 3.9 to 2.9 % (p = 0.022). Median serum TSH levels increased from 0.69 mIU/L to 1.19 mIU/L (p = <0.001). Consequently, prevalence of high TSH (mIU/L) increased from 2.6 to 2.9 % (p = 0.452), and low TSH (mIU/L) decreased from 6.6 to 6.4 % (p = 0.737).

CONCLUSION

The decreased prevalence of iodine-deficient disorders and a stable prevalence of markers of autoimmune thyroid disorders argue for an improved iodine supply of the adult population in Northeast Germany. In contrast, the prevalence of diagnosed thyroid disorders and the intake of thyroid medication increased, although this might be related to inappropriate therapeutic decisions.

Recent data on iodine intake in Germany and Europe

Iodine is essential for the synthesis of thyroid hormones. These regulate metabolism, promote growth, development and maturation of all organs, especially the brain. Most iodine is found in oceans and most continental soil and ground water is deficient in iodine. Therefore, around 2 billion individuals are estimated to have insufficient iodine intake and are at risk of iodine deficiency disorders. The best carrier for save iodine supplementation is salt, as the daily intake of salt is mainly constant. Due to the collaboration between international and national organisations and the salt industry, many developing and developed countries introduced universal salt iodization (USI) or have mandatory or voluntary fortification programs. In Germany as in most European countries the use of iodized salt is voluntary not only in household but also in the food industry. Two recent epidemiological surveys in Germany revealed that 33% of children and 32% of adults are still suffering from mild to moderate iodine deficiency. The best surrogate parameter for iodine deficiency is goitre. The goitre prevalence is around 30% in children as well as in adults which is in accordance with the documented iodine deficiency. From other European countries epidemiological derived data on iodine intake are only available from Denmark and Poland. Further efforts are under way to reveal the iodine status with proper methods in all European countries. On this background it might be possible to establish adequate iodine fortification programs in all European countries.

Various Possible Toxicants Involved in Thyroid Dysfunction: A Review

About 300 million people across the world suffer from thyroid gland dysfunction. Environmental factors play an important role in causation of autoimmune thyroid diseases in susceptible individuals. Genetics contributes to 70% of the risk. In order to reduce the risk, we need to understand the association of environmental agents with thyroid dysfunction. These factors are especially relevant for those at increased risk due to positive family history. The ideal study to see the impact of a thyroid toxicant consists of directly measuring the degree of exposure to toxicant in an individual with his thyroid status. Knowledge of various factors influencing thyroid dysfunction can help in interpreting the results of such studies in a better way. This article is an attempt to highlight the various possible toxicants affecting thyroid function so that adequate measures can be undertaken to control excessive exposure in future to reduce the prevalence of thyroid disorders.

Genomics and phenomics of Hashimoto's thyroiditis in children and adolescents: a prospective study from Southern India

BACKGROUND

Hashimoto's thyroiditis (HT) is the commonest cause of acquired hypothyroidism in children and adolescents in iodine non-endemic areas. The genetic analysis in HT shows two types of susceptibility genes-immune regulatory and thyroid specific genes. The exact genotype-phenotypic correlations and risk categorization of hypothyroid phenotypes resulting from these known mutations are largely speculative. The genetic studies in pediatric HT are very sparse from Indian sub-continent. In this context, we analysed the prevalence of TPO, NIS and DUOX2 gene mutations along with genotype-phenotype correlations in hypothyroid children with HT.

METHODS

This is inter-disciplinary study conducted by collaboration between a tertiary care endocrinology hospital, biochemistry department of a teaching medical institute and genetics lab. In this prospective study, we employed 8 sets of primers and screened for 142 known single nucleotide polymorphisms in TPO, NIS, DUOX2 genes. The subjects were children and adolescents with hypothyroidism due to HT. Congenital hypothyroidism, iodine deficiency and dyshormonogenetic hypothyroidism cases were excluded.

RESULTS

We detected 8 mutations in 7/20 (35%) children in the entire cohort (6 in NIS and 2 in TPO genes. No mutations were observed in DUOX2 gene. All our mutations were localized in introns and we found none in exons. Except for bi-allelic, synonymous polymorphism of TPO gene in child No. 18, all other mutations were heterozygous in nature. Genotype-phenotype correlations show that our mutations significantly expressed the presence of associated autoimmune manifestations and existence of family history. Clinical phenotypes of painful thyroiditis, severity of hypothyroidism and absence of goiter were statistically significant in the presence of these mutations. But, they could not reach significance on multivariate analysis.

CONCLUSIONS

NIS gene followed by TPO mutations appears to be most prevalent mutations in HT amongst South Indian children and these mutations significantly influenced phenotypic expressions such as severity of hypothyroidism, goiter, auto-immune manifestations and family history.

Determination of thyrotropin reference values in an adult Mexican population

BACKGROUND AND OBJECTIVE

The upper limit of TSH reference level is controversial. The purpose of our study was to determine TSH reference values in a Mexican population in accordance with the National Academy of Clinical Biochemistry (NACB) criteria and in correlation with thyroid ultrasound (US) examination.

PATIENTS AND METHODS

The study was conducted in volunteers with no known thyroid disease. We recruited 482 subjects, most of them medical or administrative staff from our hospital. They answered a questionnaire on demographic data, family history, co-morbidities, and drug use. Their thyroid hormone levels and thyroid antibodies were determined, and a complete physical examination and thyroid US were performed. The population used to establish the TSH reference intervals was selected according to the NACB criteria and their normal thyroid structural and echogenic characteristics in US examination.

RESULTS

Among 482 subjects (209 males) with a median age of 26 years, prevalence rates of TPOAb and TgAb were 9.3% and 10.3% respectively. Mean TSH level in the overall population was 1.90±1.94, with a 97.5th percentile of 6.76 mIU/L. The reference population was limited to 282 subjects (41.5% were excluded) with a mean TSH of 1.86±1.63 and a 97.5th percentile of 4.88 mIU/L. No sex difference was found (p=0.287). Median urinary iodine level in the reference population was 267 μg/L IQR (161.3-482.5).

CONCLUSIONS

The TSH reference interval in the reference population was 0.71 (CI 0.65-0.77) to 4.88 mIU/L (CI 4.5-5.3); these limits may be influenced by iodine nutritional status in this population.

2014 European thyroid association guidelines for the management of subclinical hypothyroidism in pregnancy and in children

This guideline has been produced as the official statement of the European Thyroid Association guideline committee. Subclinical hypothyroidism (SCH) in pregnancy is defined as a thyroid-stimulating hormone (TSH) level above the pregnancy-related reference range with a normal serum thyroxine concentration. Isolated hypothyroxinaemia (defined as a thyroxine level below the 2.5th centile of the pregnancy-related reference range with a normal TSH level) is also recognized in pregnancy. In the majority of SCH the cause is autoimmune thyroiditis but may also be due to iodine deficiency. The cause of isolated hypothyroxinaemia is usually not apparent, but iodine deficiency may be a factor. SCH and isolated hypothyroxinaemia are both associated with adverse obstetric outcomes. Levothyroxine therapy may ameliorate some of these with SCH but not in isolated hypothyroxinaemia. SCH and isolated hypothyroxinaemia are both associated with neuro-intellectual impairment of the child, but there is no evidence that maternal levothyroxine therapy improves this outcome. Targeted antenatal screening for thyroid function will miss a substantial percentage of women with thyroid dysfunction. In children SCH (serum TSH concentration >5.5-10 mU/l) normalizes in >70% and persists in the majority of the remaining patients over the subsequent 5 years, but rarely worsens. There is a lack of studies examining the impact of SCH on the neuropsychological development of children under the age of 3 years. In older children, the evidence for an association between SCH and impaired neuropsychological development is inconsistent. Good quality studies examining the effect of treatment of SCH in children are lacking.

Prevalence of hypothyroidism in adults: An epidemiological study in eight cities of India

BACKGROUND

Hypothyroidism is believed to be a common health issue in India, as it is worldwide. However, there is a paucity of data on the prevalence of hypothyroidism in adult population of India.

MATERIALS AND METHODS

A cross-sectional, multi-centre, epidemiological study was conducted in eight major cities (Bangalore, Chennai, Delhi, Goa, Mumbai, Hyderabad, Ahmedabad and Kolkata) of India to study the prevalence of hypothyroidism among adult population. Thyroid abnormalities were diagnosed on the basis of laboratory results (serum FT3, FT4 and Thyroid Stimulating Hormone [TSH]). Patients with history of hypothyroidism and receiving levothyroxine therapy or those with serum free T4 <0.89 ng/dl and TSH >5.50 μU/ml, were categorized as hypothyroid. The prevalence of self reported and undetected hypothyroidism, and anti-thyroid peroxidase (anti-TPO) antibody positivity was assessed.

RESULTS

A total of 5376 adult male or non-pregnant female participants ≥18 years of age were enrolled, of which 5360 (mean age: 46 ± 14.68 years; 53.70% females) were evaluated. The overall prevalence of hypothyroidism was 10.95% (n = 587, 95% CI, 10.11-11.78) of which 7.48% (n = 401) patients self reported the condition, whereas 3.47% (n = 186) were previously undetected. Inland cities showed a higher prevalence of hypothyroidism as compared to coastal cities. A significantly higher (P < 0.05) proportion of females vs. males (15.86% vs 5.02%) and older vs. younger (13.11% vs 7.53%), adults were diagnosed with hypothyroidism. Additionally, 8.02% (n = 430) patients were diagnosed to have subclinical hypothyroidism (normal serum free T4 and TSH >5.50 μIU/ml). Anti - TPO antibodies suggesting autoimmunity were detected in 21.85% (n = 1171) patients.

CONCLUSION

The prevalence of hypothyroidism was high, affecting approximately one in 10 adults in the study population. Female gender and older age were found to have significant association with hypothyroidism. Subclinical hypothyroidism and anti-TPO antibody positivity were the other common observations.

Genetic and epigenetic mechanisms in thyroid autoimmunity

Autoimmune thyroid diseases (AITD), including Graves' disease and Hashimoto's thyroiditis, are among the commonest autoimmune disorders, affecting approximately 5 % of the population. Epidemiological data support strong genetic influences on the development of AITD. Since the identification of HLA-DR3 as a major AITD susceptibility gene, there have been significant advances made in our understanding of the genetic mechanisms leading to AITD. We have shown that an amino acid substitution of alanine or glutamine with arginine at position 74 in the HLA-DR peptide binding pocket is a critical factor in the development of AITD, and we are continuing to dissect these mechanisms at the molecular level. In addition to the MHC class II genes, there are now several other confirmed gene loci associated with AITD, including immune-regulatory (CD40, CTLA-4, PTPN22, FOXP3, and CD25) and thyroid-specific genes (thyroglobulin and TSHR). Mechanistically, it is postulated that susceptibility genes interact with certain environmental triggers to induce AITD through epigenetic effects. In this review, we summarize some of the recent advances made in our laboratory dissecting the genetic-epigenetic interactions underlying AITD. As shown in our recent studies, epigenetic modifications offer an attractive mechanistic possibility that can provide further insight into the etiology of AITD.

Thyroid status two decades after salt iodization: country-wide data in school children from India

OBJECTIVE

Country-wide evaluation of thyroid disorders in school children following two decades of universal salt iodization (USI) has not been carried out till date. This study was planned with aim to assess thyroid status of school children two decades after the launch of USI programme.

DESIGN

Population survey.

PATIENTS

We collected data from 25 schools in 19 cities across five different geographical zones of India. Those children who were evaluated for anthropometry, and goitre status by palpation formed 'total population'. Children who consented to give blood samples were defined as 'study population'.

MEASUREMENTS

Serum free T3, free T4, TSH, anti-TPO antibody and thyroid ultrasound.

RESULTS

A total of 38,961 children aged 5-15 years formed total population. Goitre rate was 15.5% while thyroid hypoechogenicity was found in 4404 (11.3%) children. In the study population (13,790 children), 2258 (16.4%) had goitre, 505 (3.7%) had positive anti-TPO antibody titres, 1001 (7.3%) had hypothyroidism (TSH > 5.2 μIU/ml) and 41 (0.3%) had thyrotoxicosis (TSH < 0.1 μIU/ml). Among goitrous children, 203 (9.0%) had anti-TPO positivity, 365 (16.1%) had hypoechogenicity of thyroid and either of these were present in 488 (21.6%) children.

CONCLUSIONS

Endemic goitre in school children persisted nationwide, despite more than two decades of USI programme. Thyroid autoimmunity only partially explains the increase in goitre prevalence.

Cutting edge: the etiology of autoimmune thyroid diseases

Significant progress has been made in our understanding of the mechanisms leading to autoimmune thyroid diseases (AITD). For the first time, we are beginning to unravel these mechanisms at the molecular level. AITD, including Graves' disease (GD) and Hashimoto's thyroiditis (HT), are common autoimmune diseases affecting the thyroid. They have a complex etiology that involves genetic and environmental influences. Seven genes have been shown to contribute to the etiology of AITD. The first AITD gene discovered, HLA-DR3, is associated with both GD and HT. More recently, this association was dissected at the molecular level when it was shown that substitution of the neutral amino acids Ala or Gln with arginine at position beta 74 in the HLA-DR peptide binding pocket is the specific sequence change causing AITD. Non-MHC genes that confer susceptibility to AITD can be classified into two groups: (1) immune-regulatory genes (e.g., CD40, CTLA-4, and PTPN22); (2) thyroid-specific genes-thyroglobulin and TSH receptor genes. These genes interact with environmental factors, such as infection, likely through epigenetic mechanisms to trigger disease. In this review, we summarize the latest findings on disease susceptibility and modulation by environmental factors.

Dynamic changes of CD4+CD25 + regulatory T cells in NOD.H-2h4 mice with iodine-induced autoimmune thyroiditis

Iodine is an essential trace element for thyroid hormone synthesis and metabolism, either low or high intake may lead to thyroid disease, but the pathogenetic mechanisms by which iodine interacts with the thyroid autoimmune are poorly understood. We investigated the dynamic changes of CD4(+)CD25(+) regulatory T cells in NOD.H-2(h4) mice with iodine-induced autoimmune thyroiditis (AIT), and explore potential immune mechanism of AIT induced by iodine. NOD.H-2(h4) mice were randomly divided into two groups, and received plain water or water containing 0.005% sodium iodide. Eight weeks after iodine provision, the incidences of thyroiditis, relative weights of thyroids, and serum thyroglobulin antibody titers in the iodine-supplied groups were significantly increased compared to the control groups (p < 0.05). The AIT mice had fewer CD4(+)CD25(+)Foxp3(+) T cells and reduced Foxp3 mRNA expression in splenocytes compared with the controls (p < 0.01), and maintained relatively low levels during the development of thyroiditis. The changes described above aggravated gradually with the extension of iodine treatment. These data suggest that CD4(+)CD25(+) regulatory T cells may be involved in the pathogenesis and development of AIT induced by iodine.

The incidence of lymphocytic thyroid infiltration and Hashimoto's thyroiditis increased in patients operated for benign goiter over a 31-year period

The incidence of Hashimoto's thyroiditis (HT) seems to have increased over the last several decades. Since there is a lack of recent studies in the literature that evaluate this phenomenon on a histological basis, we aimed to assess the incidence of lymphocytic thyroid infiltration (LTI) in our large surgical patient collective over a 31-year period. In our study, a total of 1,050 patients who had undergone uni- or bilateral thyroid surgery for benign goiter were included (150 patients in each group, during 1979 to 2009). The stored histological sections of the removed thyroid specimens were re-analyzed, including routine grading of LTI severity on a scale of 0-4, according to Williams and Doniach. Positive correlations were seen for the incidences of LTI grading (0-4) (r = 0.077, p = 0.013) and HT (r = 0.044, p = 0.078) over the years. Furthermore, when comparing the years 1979-1989 and 1994-2009, i.e., before and after the second iodine prophylaxis had been introduced in Austria, a higher incidence of HT was found for the later years (2 out of 450, 0.4%, vs. 6 out of 600, 1.0%, respectively; p < 0.0001). In conclusion, the data demonstrate that the incidence of LTI and HT has increased substantially over the last 31 years.

The sphingosine 1-phosphate receptor modulator FTY720 prevents iodide-induced autoimmune thyroiditis in non-obese diabetic mice

FTY720 is an immunomodulator that alters migration and homing of lymphocytes via sphingosine 1-phosphate receptors. This compound has been shown to be effective in suppressing autoimmune diseases in experimental and clinical settings. In the present study, we tested whether FTY720 prevented autoimmune thyroiditis in iodide-treated non-obese diabetic (NOD) mice, a model of Hashimoto's thyroiditis (HT) in humans. Mice were given 0.05% iodide water for 8 weeks, and this treatment effectively induced thyroiditis. Iodide-treated mice were injected intraperitoneally with either saline or FTY720 during the iodide treatment. FTY720 clearly suppressed the development of thyroiditis and reduced serum anti-thyroglobulin antibody levels. The number of circulating lymphocytes and spleen cells including CD4(+) T cells, CD8(+) T cells, and CD4(+)Foxp3(+) T cells was decreased in FTY720-treated mice. Our results indicate that FTY720 has immunomodulatory effects on iodide-induced autoimmune thyroiditis in NOD mice and may be a potential candidate for use in the prevention of HT.

Postpartum thyroiditis: an autoimmune thyroid disorder which predicts future thyroid health

Postpartum thyroiditis is a potentially destructive lymphocytic thyroiditis occurring in approximately 8% of the pregnant population, making it the most common endocrine disorder associated with pregnancy. This autoimmune thyroid disorder is precipitated by the postpartum immunological rebound that follows the partial immunosuppression of pregnancy, in individuals already at risk of autoimmune thyroid disease. The manifestations of postpartum thyroiditis are usually not present at the six-week postpartum visit and thus it is important that all physicians be aware of the risks, presentation and intervention required for this common disorder. Postpartum thyroiditis is a strong predictor of future thyroid health and it is essential that women with a history of postpartum thyroiditis be screened regularly, especially prior to a future pregnancy. Selenium supplementation has recently been identified as a potential means to prevent postpartum thyroiditis in women at risk but further studies are required before recommendations for its use can be made.

Investigations of thyroid hormones and antibodies in obesity: leptin levels are associated with thyroid autoimmunity independent of bioanthropometric, hormonal, and weight-related determinants

OBJECTIVES

Obesity can alter the thyroid hormone status as a result of a dysregulated endocrine loop between the hypothalamo-pituitary unit and adipose tissue. The adipocytokine leptin has been shown to promote autoimmunity; hence, we aimed to clarify whether leptin excess of obesity could increase the susceptibility to develop autoimmune thyroid disease (AITD).

STUDY DESIGN

This cross-sectional study was performed in a tertiary care center.

METHODS

Free thyroid hormones, TSH, thyroglobulin, and antithyroid antibodies levels were tested in 165 obese and 118 lean subjects. Results were plotted against variables related to body composition, leptin levels, glucose homeostasis, energy expenditure, and pattern of weight accrual.

RESULTS

Compared with controls, obese patients had lower free T3 levels and free T4 levels (P<0.01), greater prevalence of hypothyroidism (P<0.05), and higher commonness of antithyroid antibodies (P<0.05). As a marker of AITD, thyroid peroxidase antibodies were more frequent in the obese group (P<0.01). Correlation analysis showed that leptin levels were associated with AITD (P<0.01) independent of bioanthropometric variables. Multiple logistic regression analysis in pooled groups identified female sex and leptin as significant predictors of AITD.

CONCLUSIONS

Obesity increases the susceptibility to harbor AITD with an emerging role for leptin as a peripheral determinant, which needs to be confirmed in future investigations.

Environmental exposures and autoimmune thyroid disease

BACKGROUND

Environmental exposures, ranging from perchlorate in rocket fuel to polychlorinated biphenols, have been shown to influence thyroid function. Although most of these agents are associated with reduced thyroid hormone levels or impaired thyroid hormone action, a number of environmental exposures confer an increased risk of autoimmune thyroid disease.

SUMMARY

Factors that increase autoimmune thyroid disease risk include radiation exposure, both from nuclear fallout and medical radiation, increased iodine intake, as well as several contaminants in the environment that influence the thyroid. Although approximately 70% of the risk for developing autoimmune thyroid disease is attributable to genetic background, environmental triggers are thought to play a role in the development of autoimmune thyroid disease in susceptible individuals.

CONCLUSIONS

Understanding the association of environmental agents with thyroid dysfunction can be utilized to reduce the risk to populations. Knowledge of the specific factors that trigger autoimmune thyroid disease and their mode of action, however, may also inform risk reduction in the individual patient. These factors are especially relevant for those at increased risk of autoimmune thyroid disease based on family history.

Iodine nutrition in Brazil: where do we stand?

Brazilian legislation, since 1955, failed to achieve its objectives because the issue was not properly addressed: iodized salt was only available in endemic areas, at a low amount of 10 mg Iodine/kg salt. Lack of surveillance and cooperation were common errors. From 1982 to 1992, the INAN distributed potassium iodate to the industry free of charge, but it was abolished in 1991. Only four years later (1995) was a new law enacted effective in determining that all salt for human use should be iodized at levels established by the Health Authorities. During the period comprising 1998 to 2004, excessive iodination of salt (40 to 100 mg/kg) could lead to an increased prevalence of chronic autoimmune thyroiditis and iodine-induced hyperthyroidism. In 2003, the content of iodine/kg of salt was lowered to 20 to 60 mg I/kg salt. A national survey of schoolchildren is currently underway and will indicate the changes required for adequate iodine in salt for human use.

Iodide-induced chemokines and genes related to immunological function in cultured human thyroid follicles in the presence of thyrotropin

BACKGROUND

It is well known that iodide exacerbates thyroid function in subclinical hypothyroid patients with autoimmune thyroiditis. To investigate the immunological mechanism of iodine-induced thyroid dysfunction, we studied the effect of iodide in cultured human thyroid follicles, which respond to physiological concentrations of human thyrotropin (TSH) (0.3-10 microU/mL) and maintain the Wolff-Chaikoff effect.

MATERIALS AND METHODS

Thyroid follicles obtained from Graves' patients at subtotal thyroidectomy were precultured in medium containing 0.5% fetal calf serum and 10(-8) M iodide for 5 days, and then cultured with the medium containing bovine TSH (30 microU/mL) and low (10(-8)M) or high (10(-5)M) concentrations of iodide. After 3-72 hours of culture, the effect of iodide on thyroid cell mRNA expression was analyzed by microarray and reverse transcriptase-polymerase chain reaction.

RESULTS

After 48 hours of culture, iodide nearly doubled the mRNA expression levels of the immunity-associated genes (intercellular adhesion molecule-1, transforming growth factor beta 1-induced protein, early growth response gene 1, guanylate-binding protein 1, and annexin A1) and decreased the mRNA expression of sodium-iodide symporter to less than 20%. Further, the mRNA expression levels of chemokines (CCL2, CXCL8, and CXCL14) increased nearly twofold, whereas their receptors did not show any significant response. Real-time polymerase chain reaction analyses confirmed that iodide increased the mRNA expression levels of these genes in a time- and concentration-dependent manner. Immunohistochemical studies revealed that the chemokines were expressed mainly in the thyroid follicular cells in addition to the immune cells. The iodide-induced increase in CCL2 was greater in thyroid follicles obtained from thyroid gland that had been moderately infiltrated with the immunocompetent cells.

CONCLUSION

We have demonstrated that iodide stimulates thyroid follicular cells to produce chemokines, particularly CCL2, CXCL8, and CXCL14. These chemokines and intercellular adhesion molecule-1 would attract immunocompetent cells into thyroid gland. These in vitro findings suggest that iodide at high concentrations may induce thyroid dysfunction through not only biochemical but also immunological mechanisms, particularly in patients with autoimmune thyroid disorders.

Assessment of urinary iodine excretion among normal Kuwaiti adults

This study was performed to investigate the status of iodine intake among the Kuwaiti population and its effect on thyroid function. The study group was comprised of 139 females and 86 males with a mean age of 33 and 35 years, respectively. Urinary iodine excretion (UIE) and serum free T4 (FT4), thyrotropin hormone (TSH), antiperoxidase antibodies (anti- TPOAb), and antithyroglobulin antibodies (anti-TGAb) were determined. Median UIE was 148 μg/L (within the recommended level by the World Health Organization [WHO]). However, UIE levels of <100 and <50 μg/L were detected in both male and female groups, respectively. Serum levels of TSH and FT4 were normal for all except one of the participants who suffered from hyperthyroidism, possibly as a result of elevated iodine intake, which was reflected in an increased UIE of 590 μg/L. Elevated anti-TPOAb >75 IU/mL and anti-TGAb >150 IU/mL were detected in 15% and 34% of subjects; only 10% of them had elevated levels of both anti-TPOAb and anti-TGAb. Thus, based on the WHO recommendations, the iodine intake for the Kuwaiti population is adequate. However, it is recommended that a national study be conducted by the appropriate authority in order to eliminate any artifacts which may have appeared in this study.

Development of thyroid diseases in the treatment of chronic hepatitis C with alpha-interferon may be a good prognosticator in achieving a sustained virological response: a meta-analysis

BACKGROUND AND AIM

Thyroid dysfunction is the most common endocrinopathy associated with hepatitis C and its interferon-based treatment. When undergoing treatment, interferon and ribavirin synergize to potently stimulate the immune system in order to eradicate the virus. One of the innocent bystanders in this accentuated response is the thyroid. The present study investigated whether thyroid dysfunction while undergoing combination treatment for hepatitis C is a favorable prognostic maker for a sustained virological response.

METHODS

We carried out a prospective clinical audit in 201 patients treated with combination ribavirin and alpha-interferon and determined the prevalence of sustained virological response in patients in association with thyroid disease. A meta-analysis was also carried out pooling 741 patients from four previous studies on this topic.

RESULTS

There was positive and significant association between thyroid disease and viral clearance. This was not supported by the meta-analysis, however, and some plausible explanations are proffered for this inconsistency.

CONCLUSION

Despite lacking supportive evidence from the meta-analysis, it is important that this information is confirmed (or refuted) in future studies.

Patogênese das doenças tiroidianas autoimunes

A doença tiroidiana autoimune (DAIT), que afeta de 2% a 5% da população ocidental, é o transtorno autoimune órgão-específico mais comum. Sua apresentação clínica varia do hipertiroidismo da doença de Graves (DG) ao hipotiroidismo associado à tiroidite de Hashimoto (TH). A exata etiologia da DAIT permanece desconhecida, mas a interação entre suscetibilidade genética e fatores ambientais desencadeadores parece ser de fundamental importância no seu desenvolvimento. Postula-se que fatores genéticos responderiam por 79% da suscetibilidade à DAIT e os ambientais por 21%. Genes imunomoduladores, como o complexo maior de histocompatibilidade (MHC), antígeno-4 associado ao linfócito T citotóxico (CTLA-4), a molécula CD40 e a proteína tirosina fosfatase-22 (PTPN22) e os genes específicos da glândula tiróide, como receptor do TSH (TSHR) e tiroglobulina (TG) têm sido identificados. A natureza exata do envolvimento do meio ambiente no desenvolvimento da DAIT não é bem conhecida, mas vários fatores ambientais têm sido envolvidos, como o conteúdo de iodo na dieta, estresse, drogas e infecções. Entretanto, não há evidência clara de causalidade e os mecanismos pelos quais fatores ambientais desencadeariam a autoimunidade tiroidiana, em indivíduos geneticamente predispostos, ainda permanecem não completamente entendidos. O conhecimento dos mecanismos precisos de interação entre fatores ambientais e genes na indução da autoimunidade tiroidiana poderia resultar desenvolvimento de novas estratégias de prevenção e tratamento.

Thyroid autoimmunity in schoolchildren in an area with long-standing iodine sufficiency: correlation with gender, pubertal stage, and maternal thyroid autoimmunity

BACKGROUND

A strong genetic background and gender are believed to be involved in thyroid autoimmunity (TA). The age these factors become manifest is less clear, however. The objective of the present study was to determine the prevalence of TA in children and adolescents and to determine if there are relationships between the period of onset of TA and gender and between TA and maternal autoimmunity.

METHODS

Antithyroperoxidase antibodies (anti-TPO Ab), antithyroglobulin antibodies (anti-Tg Ab), thyrotropin, thyroxine, triiodothyronine, and urinary iodine were determined in 440 healthy schoolchildren (200 boys and 240 girls), aged 5-18 years, and in 123 mothers living in an iodine-replete region.

RESULTS

The prevalence of positive anti-TPO and anti-Tg Ab was 4.6% and 4.3%, respectively. In girls, the prevalence of positive anti-TPO Ab was higher in Tanner stage II-V compared to Tanner stage I (8.2% vs. 2.2%; p < 0.05). No difference was detected with regard to anti-Tg Ab. In girls, positive anti-TPO and anti-Tg Ab levels were associated with significantly greater thyroid volume. Hypoechogenicity was detected in 52.6% and 36.8% of the children with positive anti-TPO or anti-Tg Ab, respectively (p = 0.0005). The prevalence of autoimmune thyroiditis, as defined by positive serum anti-TPO and/or anti-Tg and an echographic pattern of the thyroid gland having diffuse or irregular hypoechogenicity, was 2.5%. Mothers of anti-TPO Ab positive children had positive anti-TPO Ab more frequently compared to mothers of anti-TPO Ab negative children (82% vs. 18%; p = 0.0005). Mothers of anti-Tg Ab positive children had positive anti-Tg Ab more frequently compared to mothers of anti-Tg Ab negative children (75% vs. 25%; p = 0.0005).

CONCLUSIONS

These findings demonstrate that thyroid antibody positivity in children was significantly associated with maternal autoimmunity and their development in girls emerges at puberty. Since heredity, female gender, and puberty are strongly associated with TA, girls in families with TA should be examined at the onset of puberty.

Thyroid cancer, thyroiditis and dietary iodine: a review based on the Salta, Argentina model

Factors that should be considered when studying the effect of dietary iodine in the development of thyroid cancer include pathological criteria, diagnostic techniques, screening programs, radioactive fallout, and standard of medical care in the studied population. In most surveys, papillary carcinoma forms the largest group of thyroid malignancies, both before and after iodine prophylaxis where an increase in the papillary:follicular carcinoma ratio is also noted. Undifferentiated carcinomas decrease after salt prophylaxis. In Salta, Argentina, the increasing incidence of clinically significant papillary thyroid cancer and the decrease of undifferentiated carcinoma after iodine prophylaxis are probably due to better access to health centers and consequent earlier detection of differentiated precursor tumors. Autoimmune focal and diffuse or Hashimoto's thyroiditis are linked to dietary iodine. Pathological studies made in different regions indicate that these types of thyroiditis occur more frequently in areas of iodine sufficiency than in areas of iodine deficiency, and increase after iodine prophylaxis both in non-goitrous and iodine-deficient areas like Salta, Argentina. An increase of lymphocytic thyroiditis could be linked to an increased incidence of primary thyroid lymphoma, and thyroiditis is more commonly associated with papillary carcinoma than with other types of thyroid follicular or C-cell derived carcinomas regardless of iodine intake.