More than adequate iodine intake may increase subclinical hypothyroidism and autoimmune thyroiditis: a cross-sectional study based on two Chinese communities with different iodine intake levels

Residential Greenness Is Associated with Lower Thyroid Nodule Prevalence: A Nationwide Study in China

Background: The prevalence of thyroid nodules is increasing globally. This study explored the association between residential greenness and thyroid nodule prevalence. Methods: Data were collected from a national cross-sectional survey of 73,728 participants across 31 provinces in mainland China. Residential greenness was assessed with the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI). Thyroid nodules >10 mm in diameter were diagnosed via ultrasound. We used quartile comparisons of the NDVI and EVI to compare nodule prevalence and employed logistic regression and restricted cubic spline analyses to examine nodules' associations with greenness. Interaction and sensitivity analyses were performed to test robustness. Results: A total of 73,728 participants were included in this study. The prevalence of 10 mm thyroid nodules decreased across NDVI500 quartiles: Q1: 7.99% (7.59-8.39%), Q2: 10.04% (9.60-10.48%), Q3: 6.59% (6.23-6.95%), and Q4: 5.20% (4.88-5.52%) (p for trend <0.001). The prevalence was 5.25% (95% confidence interval [CI]: 5.02-5.49%) in males and 9.09% (CI: 8.80-9.39%) in females. Logistic regression analysis showed that greater residential greenness was associated with a lower prevalence of thyroid nodules after adjusting for all covariates. This association was observed for both continuous greenness measures (NDVI500: odds ratio [OR] = 0.20, CI: 0.16-0.25; EVI500: OR = 0.08, CI: 0.06-0.12) and across quartiles (NDVI500 Q4: OR = 0.53, CI: 0.48-0.58; EVI500 Q4: OR = 0.55, CI: 0.51-0.60; both compared to Q1). Multiple sensitivity analyses confirmed this negative association, including the use of an alternative thyroid nodule definition (5 mm threshold), exclusion of individuals with cysts on ultrasound, and subgroup analyses excluding individuals with autoimmune thyroid antibody positivity, goiter, or both. In all these sensitivity analyses, NDVI and EVI data were assessed using both 500 m and 1000 m buffers. Conclusion: Our study is the first to identify an association between higher levels of residential greenness and a lower prevalence of thyroid nodules.

A Scoping Review on the Prevalence of Hashimoto's Thyroiditis and the Possible Associated Factors

BACKGROUND

Hashimoto's thyroiditis (HT) is the most common autoimmune thyroid disease (AITD) and is characterized by the presence of thyroid autoantibodies against thyroid peroxidase and/or thyroglobulin. Several studies have found that the global prevalence of HT has increased in recent decades, while others show the opposite.

METHODS AND RESULTS

The objective of this scoping review was to synthesize and analyze the different studies that have evaluated the prevalence of HT (in adults) and the possible associated factors. The following databases were consulted, as follows: MEDLINE, Web of Science, PubMed, and Scopus. The search terms "epidemiology", "prevalence", and "Hashimoto disease" and "Hashimoto thyroiditis" were used. The search was limited to articles published between January 1965 and October 2024, and only articles in English were considered. In order to reduce selection bias, each article was scrutinized using the JBI Critical Appraisal Checklist independently by two authors. Studies were included if the number of participants (study population and/or cases and controls, depending on the study design) was clearly described and duplicate studies were excluded. A total of 59 studies were identified, the vast majority of them used a cross-sectional design, using different methods of disease assessment.

CONCLUSIONS

Globally, the prevalence of HT is estimated to be between 5-10%; some areas with prevalences > 20% and others < 0.5% were identified. Prevalence is also higher in women than in men. Multiple underlying factors (genetic, epigenetic, environmental, and lifestyle), together with socioeconomic, nutritional, overdiagnosis, inter alia, may explain (at least in part) the wide variability in the prevalence of HT.

Beyond thyroid dysfunction: the systemic impact of iodine excess

As an essential micronutrient, iodine plays a crucial role in several physiological systems, particularly in the production of thyroid hormone. While deficiency is widely recognized, the consequences of iodine excess (IE) are less studied. IE, which may be caused by iodine-rich diets, supplements, iodinated contrast media and salt iodization, has been implicated in a range of adverse outcomes on thyroid and systemic health. Examples include autoimmune thyroid diseases like Graves' disease and Hashimoto's thyroiditis, driven by immune cell polarization and gut microbiota alterations. Furthermore, excessive iodine intake is associated with increased risks of cardiovascular diseases, including hypertension and atherosclerosis, due to oxidative stress, inflammation, and endothelial dysfunction. It contributes to the development of thyroid cancer, particularly papillary thyroid cancer, through genetic mutations such as BRAF mutations and enhanced cancer cell proliferation. Excess iodine intake has been implicated to have neurotoxic effects, significantly impairing learning and memory, negatively impacting neonatal brain development, and potentially contributing to the progression of neurodegenerative conditions. It also has a potential role in renal dysfunction in vulnerable populations, due to overload from povidone-iodine in sterile equipment. This mini-review aims to collate the adverse effects of IE, beyond its effect on thyroid health, through investigation of the cardiovascular, nervous, and renal systems. Through our consolidation of the current literature, we hope to raise awareness and contribute to the understanding of the multifaceted impact of excessive iodine intake.

A Case of Thyrotoxicosis and Excess Iodine Due to Habitual Use of Polyvinylpyrrolidone Iodine while Gargling in an Iodine-sufficient Area

Excess iodine can influence the pathophysiology of the thyroid gland and results of various thyroid-related examinations. We herein report a 60-year-old Japanese man with thyrotoxicosis and excess iodine due to habitual use of polyvinylpyrrolidone iodine (PVP-I) to gargle for 20 years. Initial laboratory and imaging findings were suggestive of painless thyroiditis. However, after cessation of PVP-I use for gargling, these results changed to findings suggestive of Graves' disease, with worsening thyrotoxicosis. A detailed questionnaire regarding excess iodine is important for the accurate diagnosis of thyrotoxicosis, even in patients living in iodine-sufficient areas where iodine-induced thyrotoxicosis is rare.

Reference Ranges and Determinants of Thyroid Function and TSH Receptor Antibodies During Early Pregnancy in Nepal

OBJECTIVE

Different definitions of thyroid dysfunction during pregnancy may lead to under or overtreatment. The aims of this study were to (1) define population-based pregnancy-specific reference ranges for thyroid dysfunction during early pregnancy in Nepal and assess the impact of antibody positivity, (2) quantify the diagnostic impact of population-based reference ranges compared with current practice and (3) assess the determinants of thyroid function and antibody positivity.

METHODS

A total of 800 healthy pregnant women aged 20-40 years in the Bhaktapur municipality were included. Population-based reference ranges for thyroid hormones levels were defined as 2.5th and 97.5th percentiles using competitive immunoluminometric assay design. Thyroid disease cases and those with recommended treatment indications were calculated using current non-pregnancy new reference ranges. Multivariate regression analyses were performed to identify the determinants of thyroid hormones and antibody levels.

RESULTS

Median gestational age was 11 weeks. The reference interval was 0.05-3.69 µLU/mL for thyroid stimulating hormone (TSH) and 8.89-15.28 pg/mL for free tetraiodothyronine (fT4) after excluding thyroid peroxidase antibody-positive women. Compared with the current non-pregnancy reference ranges, the new calculations increased the number of women who required treatment from 5 to 12 (0.9% increase). We identified 19 women (2.4%) who were positive for TSH receptor antibody (TRAb). We could not identify the determinants of TRAb positivity, and TRAb positivity was not associated with TSH or fT4 levels.

CONCLUSIONS

We found meaningful changes using population-based pregnancy-specific TSH and fT4 reference intervals and encourage further studies in other low- and middle-income settings. Our findings suggest that population screening for TRAb is not clinically meaningful.

TRIAL REGISTRATION

Clinical Trial Registration: U1111-1183-4093.

Iodine Excess Is Associated with Thyroid Dysfunction Among the Elderly

The relationship between high water iodine levels and thyroid dysfunction in the elderly remains poorly understood. This study aimed to elucidate how excessive iodine in drinking water affects iodine nutrition and thyroid function in the elderly population. This cross-sectional study was performed in the elderly in Yuncheng, Heze, Shandong. We identified a total of 385 patients with thyroid dysfunction and 385 propensity score-matched controls with euthyroid. Water, urinary, and blood samples were collected to detect the concentrations of iodine in water and urine, as well as thyroid hormones. The median (IQR) iodine concentrations in cooking water and drinking water for the total population were 294.99 (48.99, 478.14) µg/L and 172.87 (20.87, 462.13) µg/L, respectively. Among the elderly, median (IQR) urinary iodine concentration (UIC) was 394.20 (169.47, 764.41) µg/L, and 24-h urinary iodine concentration (24-h UIE) was 523.04 (277.84, 910.76) µg/day. Subjects with thyroid dysfunction reported higher intake of iodine from water (P < 0.001) and urinary iodine levels (P < 0.001) than controls. Logistic regression analysis showed thyroid dysfunction was associated with higher risks of elevated iodine concentrations in cooking water (OR 1.957, 95% CI 1.413-2.711), drinking water (OR 2.206, 95% CI 1.607-3.027), UIC (OR 3.612, 95% CI 2.494-5.230), and 24-h UIE (OR 2.568, 95% CI 1.784-3.698), indicating increased thyroid dysfunction risk among the elderly with high water iodine levels. Elevated iodine levels in water are associated with an increased risk of thyroid dysfunction among the elderly. Clinical trial registry number: Medical Ethics Committee of Tianjin Medical University; Trial registration number: NCT05716191, date of registration was December 08, 2023.

Acupuncture treatment for Hashimoto's thyroiditis: An exploratory randomized controlled trial

Background

Hashimoto's thyroiditis (HT) has a high incidence rate and unresolved clinical symptoms. Although Hand Yangming Meridian Penetrating Acupuncture has been used to treat thyroid diseases in China, there is no randomized controlled trial (RCT) on HT.

Methods

This exploratory RCT aims to preliminarily evaluate the efficacy, safety, and feasibility of Hand Yangming Meridian Penetrating Acupuncture in the treatment of HT. Included subjects were randomly assigned to the acupuncture group and the waiting treatment group at a ratio of 1:1. Subjects in the acupuncture group received 16 weeks of acupuncture treatment, followed by a 16-week follow-up observation phase. Subjects in the waiting group received thyroxine supplementation for 16 weeks, followed by 16 weeks of compensation treatment. Serum thyroid peroxidase antibody (TPOab) and thyroglobulin antibody (TGab) levels were the main indicators, and Thyroid-Related Patient-Reported Outcome short form (ThyPRO-39), MOS Item Short Form Health Survey (SF-36), and Hospital Anxiety and Depression Scale (HADS) scores were also recorded.

Results

In total, 58 subjects were included. After 16 weeks of treatment, there was no statistical difference in the changes in TPOab levels between the two groups, but the TGab level in the acupuncture group was significantly lower than in the waiting group (difference: -141.97 [95 % CI: -222.4 to -61.5], P = 0.011). Moreover, the total ThyPRO-39 and SF-36 scores were statistically different between the two groups (PThyPRO-39 < 0.001, PSF-36 = 0.005). There was no statistical difference in HADS between the two groups.

Conclusions

Hand Yangming Meridian Penetrating Acupuncture may be safe and feasible for HT hypothyroidism to improve symptoms and reduce TGab levels.

Trial registration number

This trial was registered at Acupuncture-Moxibustion Clinical Trial Registry: AMCTR-IOR-19000308 (ChiCTR1900026830, https://www.chictr.org.cn/searchprojEN.html).

Autoimmune thyroid status in subclinical thyroid disorders in patients attending a tertiary care center in Nepal: a hospital-based cross-sectional study

BACKGROUND

Thyroid dysfunction is the leading endocrine disorder worldwide. Iodine deficiency disorders, which were once the major etiology of thyroid dysfunctions, now have been succeeded by autoimmune thyroid diseases with the rise in aberrant salt ionization protocols. This study endeavors to access the level of thyroid autoantibodies viz. anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin (TGA), and anti-thyroid stimulating hormone receptor (TRAb) in individuals with subnormal thyroid profiles.

METHODS

This hospital-based cross-sectional study was conducted at the Department of Clinical Biochemistry, Tribhuvan University for a period of six months. Using non-probability (purposive) sampling method, a total of 60 patients were enrolled with subnormal thyroid profiles to include the population who have not yet started medication. Thyroid hormones (free T3, free T4, TSH) and thyroid antibodies (anti-TPO, TGA, and TRAb) were measured. For non-parametric data, Chi-square test and Kruskal-Wallis test were used. Spearman's correlation was done to determine the association between variables.

RESULTS

Out of 60 participants, the majority of the population between 25 and 44 years were diagnosed with thyroid dysfunction with female preponderance. Among all, 40% (n = 24) had subclinical hyperthyroid states while, 60% (n = 36) had subclinical hypothyroid states, and 75% (n = 45) of the total exhibited positive thyroid antibodies. In subclinical hypothyroid patients with TSH above 10 µIU/ml, anti TPO (58.5%) and TGA (66.7%) positivity were highly prevalent. On the other hand, TRAb was exclusively positive in hyperthyroid condition (50% among the group) which is by far the first of its kind reported in Nepal.

CONCLUSION

The rise in autoimmune thyroid disease among the Nepalese population infers that addressing iodine deficiency simply through salt iodinization may not be adequate to deal with the rising burden of thyroid disorders, especially in iodine-depleted areas. Also, the increasing prevalence of thyroid autoantibodies positivity in subclinical hypothyroidism in the Nepalese population accounts for the arduous screening and monitoring of autoimmune thyroid disorders in Nepal.

Selenium level correlates negatively with antibodies but positively with thyroid function in children with down syndrome: an Indonesian study

Background

Children with Down syndrome (DS) are prone to developing autoimmune thyroid disease (AITD). Previous studies found lower selenium (Se) levels in children with AITD. Glutathione peroxidase-3 (GPx3) and selenoprotein-P (SePP) are widely used to measure Se levels. DS children tend to have lower Se levels, the main contributor to hypothyroidism in this population. This study aimed to analyze the Se's role in AITD in Indonesian children with DS.

Methods

This cross-sectional study was conducted between February 2021-June 2022 at the Pediatric Outpatient Clinic of Dr Soetomo Hospital. DS children aged 1 month to 18 years were enrolled using consecutive sampling. Thyroid-stimulating hormone, free thyroxine, thyroid peroxidase (TPO-Ab) and thyroglobulin (Tg-Ab) autoantibody, GPx3, and SePP levels were measured in plasma samples using enzyme-linked immunosorbent assays. Statistical analyses used Chi-square, Mann-Whitney, and Spearman's rank correlation (r _s). All results with p<0.05 were considered statistically significant.

Results

Among 62 children with DS, SePP and GPx3 levels were significantly lower in those with AITD than those without AITD (p=0.013 and p=0.018, respectively). SePP and GPx3 levels correlated significantly with lower TPO-Ab (r _s=-0.439 with p=1×10^-5 and r _s=-0.396 with p=0.001, respectively) and Tg-Ab (r _s=-0.474 with p=1×10^-5 and r _s=-0.410 with p=0.001, respectively) levels. SePP levels correlated significantly with lower thyroid dysfunction incidence (r _s=-0.252, p=0.048) in the AITD group.

Conclusion

Selenium deficiency contributes to autoimmune process in the thyroid and to thyroid dysfunction in children with Down syndrome. Our findings recommend increasing Se levels through Se-containing foods to reduce the risks of AITD and thyroid dysfunction in DS children with AITD.

Comparison Between Levothyroxine and Lifestyle Intervention on Subclinical Hypothyroidism in Women: A Review

Subclinical hypothyroidism (SCH) or "mild thyroid failure" is defined as elevated serum thyroid-stimulating hormone (TSH) in the presence of normal free thyroxine (T4). The incidence of SCH is estimated at 4.4-8.5% of the general population and occurs more frequently in women. Given that it falls below the diagnostic threshold, SCH is monitored rather than treated. Its management is a common topic of debate as SCH frequently progresses into overt hypothyroidism and is linked to long-term hyperlipidemia, endothelial dysfunction, cardiovascular disease, heart failure, and cerebrovascular disease. Premature hormone administration and lifestyle interventions have been explored as treatment options to mitigate the symptoms of SCH. Our review compares both modalities' efficacy and potential for standardized clinical practice. A trial of levothyroxine demonstrated significant results in specific SCH demographics, such as patients who are pregnant or trying to conceive, those with goiter, those with thyroid peroxidase (TPO) antibody status, those with steadily increasing TSH, children, and adolescents. All other SCH patients presenting with chronic symptoms may also be reasonably considered for a three- to six-month trial of treatment. Lifestyle modifications through improved sleep hygiene, a diet within the recommended daily allowance (RDA) for iodine and selenium, increased exercise, and smoking cessation also proved efficacious. Our findings indicate that a synergistic approach to treatment is most favorable. Lifestyle modifications neither show adverse effects nor contraindications and can be safely recommended alone or alongside levothyroxine for the treatment of SCH.

Effects of Excessive Iodine on the BDNF-TrkB Signaling Pathway and Related Genes in Offspring of EAT Rats

Excess iodine can cause autoimmune thyroiditis (AIT) in women, but it is unclear whether this has any implications for neurodevelopmental mechanisms in offspring. We studied the effects of experimental autoimmune thyroiditis (EAT) rats with different amounts of iodine intake on offspring brain development via the brain-derived neurotrophic factor (BDNF)-tropomycin receptor kinase B (TrkB) signaling pathway, because BDNF plays an important role in neurodevelopment. Rats in three thyroglobulin (Tg) immunized groups with varying iodine intakes (Tg (100 µg/L iodine), Tg + High-iodine I group (Tg + HI, 20 mg/L iodine), and Tg + High-iodine II group (Tg + HII, 200 mg/L iodine)) were injected with 800 µg Tg once every 2 weeks for 3 times. Rats in the control group (NI, 100 µg/L iodine) were immunized with saline. Arsenic-cerium catalytic spectrophotometry was used to measure urine iodine levels. The lymphocytic infiltration in the thyroids was observed by histopathological studies. Thyroid autoantibodies levels were measured using radioimmunoassay. The norepinephrine (NE) contents were measured by an enzyme-linked immunosorbent assay. The levels of the BDNF-TrkB signaling pathway and related genes were measured by quantitative real-time PCR and Western blot. Urinary iodine levels increased as iodine intake increased. Lymphocytes were significantly aggravated in Tg-immunized rats. Serum thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) levels were clearly elevated in Tg-immunized rats. Tg-immune groups had significantly lower NE levels. The BDNF-TrkB signaling pathway and related gene mRNA and protein levels were found to be significantly lower in Tg-immune groups with higher iodine levels. Maternal AIT may reduce the levels of certain neurodevelopmental mechanisms in the offspring, such as the BDNF-TrkB signaling pathway and related factors, while excessive iodine consumption by the mother may exacerbate this effect.

Assessment of Red Cell Distribution Width among Sudanese Patients with Hypothyroidism.. [DOI: 10.21203/rs.3.rs-2518318/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background: Thyroid dysfunction has a strong linkage with anemia. RDW was traditionally regarded as a part of routine evaluation of anemia Elevated RDW level was significantly associated with subclinical hypothyroidism and hypothyroidism. Objectives: The aim of this is study to assess the Red Cell Distribution Width (RDW-CV and RDW-SD) in patients with hypothyroidism. Methodology: This is a case-control laboratory-based study conducted among 50 patients with hypothyroidism as cases (38.50 ± 10.46 years; 36% males and 64% females) and 50 normal healthy individuals as controls (35.52 ± 11.64 years; 46% males and 54% females) in National Cancer Institute – University of Gezira (NCI-UG), Gezira State, Sudan from January to October 2020. Three ml of venous blood sample was collected in an EDTA container. Red cell parameters (RBC count, MCV, RDW-CV, and RDW-SD) were measured using Sysmex XP 300 Cell Counter. SPSS computer program (v 22.0) was used for data analysis. Results: The average RDW (SD and CV) of cases were higher than controls (P value = 0.000, 0.000 respectively). There was a significant difference in RDW-CV between mild and severe hypothyroidism (P value = 0.040). RDW-SD and RDW-CV had significant positive correlation within TSH (r = 0.361, P value = 0.000; r = 0.407, P value = 0.000 respectively) and significant negative correlation within T3 (r = - 0.419, P value = 0.000; r = - 0.507, P value = 0.000 respectively) and T4 (r = - 0.406, P value = 0.000; r = - 0.506, P value = 0.000 respectively). Conclusion: The study concluded that RDW was significantly higher in patients with hypothyroidism and had a significant positive correlation with TSH and a significant negative correlation within T3 and T4. So, RDW may be used as a significant clinical marker of hypothyroidism.

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.

Endocrine disorders in obstructive sleep apnoea syndrome: A bidirectional relationship

Obstructive sleep apnoea (OSA) is a common disorder characterized by recurrent episodes of apnoea or hypopnea due to total or partial pharyngeal collapse and temporary upper airway obstruction during sleep. The prevalence of OSA is increasing and currently affects about 30% of men and 13% of women in Europe. Intermittent hypoxia, oxidative stress, systemic inflammation, and sleep fragmentation resulting from OSA can provoke subsequent cardiometabolic disorders. The relationships between endocrine disorders and OSA are complex and bidirectional. Indeed, several endocrine disorders are risk factors for OSA. Compared with the general population, the prevalence of OSA is increased in patients with obesity, hypothyroidism, acromegaly, Cushing syndrome, and type 1 and 2 diabetes. In some cases, treatment of the underlying endocrine disorder can improve, and occasionally cure, OSA. On the other hand, OSA can also induce endocrine disorders, particularly glucose metabolism abnormalities. Whether continuous positive airway pressure (CPAP) treatment for OSA can improve these endocrine disturbances remains unclear due to the presence of several confounding factors. In this review, we discuss the current state-of-the-art based on the review of the current medical literature for key articles focusing on the bidirectional relationship between endocrine disorders and OSA and the effects of treatment. Screening of OSA in endocrine patients is also discussed, as it remains a subject of debate.

The effect and mechanism of excessive iodine on the endothelial function of human umbilical vein endothelial cells

Iodine excess (IE) can cause thyroid dysfunction, thyroid diseases can adversely affect cardiovascular function. Accordingly, this study was to explore the direct and indirect effects of IE on endothelial function. Nthy-ori 3-1 and HUVECs cells were treated with potassium iodide (KI). CCK-8, LDH leakage, Elisa, RT-PCR and Western blotting were used to detect relevant indicators. Results showed that a certain level of KI can directly and indirectly reduce the viability of HUVECs and increase cytotoxicity. KI decreased the expression of ET-1 and VWF in HUVECs, inhibited the secretion of ET-1 in culture medium, and increased the expression of IL-6 and TNFα in HUVECs or Nthy-ori 3-1 cells alone. In the co-culture system, KI decreased the expression of ET-1 and THBD and increased the expression of TNFα and IL-6. Collectively, IE can directly and indirectly inhibit endothelial function of endothelial cells, which may be related to its induced inflammatory response.

What Iodine Intervention Measures Should Be Taken in Different Water Iodine Areas? Evidence from a Cross-sectional Chinese Survey

The aim of this study was to assess the population's iodine nutrition and thyroid diseases in different water iodine areas and to offer suggestions to the governments of different countries to adjust the present policy in different water iodine areas. A cross-sectional survey was conducted in different water iodine areas in China. Urinary iodine, water iodine, salt iodine and thyroid function were determined. The thyroid volumes and nodules were measured by ultrasound. Upon categorization by water iodine level for the 10.0 ~ 39.9 μg/L, 40.0 ~ 100.0 μg/L and 100.1 ~ 150.0 μg/L areas, in adults, the prevalence of subclinical hypothyroidism was 9.28%, 5.35% and 11.07%, and the median urinary iodine (MUI) was 153.7 μg/L, 189.8 μg/L and 317.0 μg/L; in children of the three areas, the prevalence of goitre was 3.83%, 4.47% and 16.02%, and the MUI was 164.1 μg/L, 221.0 μg/L and 323.3 μg/L; in pregnant women of those areas, the MUI was 148.6 μg/L, 176.9 μg/L and 324.9 μg/L. Logistic regression results indicated that low iodine intake was a risk factor for developing hypothyroxinaemia in pregnant women. The iodine status of pregnant women is insufficient in areas with a median water iodine level of 10.0 ~ 39.9 μg/L. Low iodine intake increases the risk of developing hypothyroxinaemia in pregnant women. The iodine status of adults and children is excessive, and the iodine status of pregnant women is above the requirements in areas with a median water iodine concentration of 100.1 ~ 150.0 μg/L. Iodized salt, especially for pregnant women, should be supplied in areas with a median water iodine concentration of 10.0 ~ 39.9 μg/L to improve the iodine status of pregnant women. Supplying non-iodized salt is not enough to protect local residents from the harm from excess iodine in areas with a median water iodine concentration above 100.0 μg/L.

Global prevalence and epidemiological trends of Hashimoto's thyroiditis in adults: A systematic review and meta-analysis

Objective

Although Hashimoto's thyroiditis is associated with cardiovascular disease and malignancy, the global status of Hashimoto's thyroiditis is not well characterized across regions. Our objective was to evaluate the prevalence and trends of Hashimoto's thyroiditis in adults in regions with different economic income levels around the world.

Methods

For this systematic review and meta-analysis, we searched PubMed, Embase, MEDLINE, Scopus, and Web of Science databases, and 48 random-effects representative studies from the inception to June 2022 were included without language restrictions to obtain the overall prevalence of Hashimoto's thyroiditis in adults worldwide. In addition, we stratified by time of publication, geographic region, economic level of the region of residence, gender, diagnostic method, etc.

Results

A total of 11,399 studies were retrieved, of which 48 met the research criteria: 20 from Europe, 16 from Asia, five from South America, three from North America, and three from Africa. Furthermore, there are two projects involving 19 countries and 22,680,155 participants. The prevalence of Hashimoto's thyroiditis was 7.5 (95%CI 5.7-9.6%), while in the low-middle-income group the prevalence was 11.4 (95%CI 2.5-25.2%). Similarly, the prevalence was 5.6 (95%Cl 3.9-7.4%) in the upper-middle-income group, and in the high-income group, the prevalence was 8.4 (95%Cl 5.6-11.8). The prevalence of Hashimoto's varied by geographic region: Africa (14.2 [95% CI 2.5-32.9%]), Oceania (11.0% [95% CI 7.8-14.7%]), South America and Europe 8.0, 7.8% (95% Cl 0.0-29.5%) in North America, and 5.8 (95% Cl 2.8-9.9%) in Asia. Although our investigator heterogeneity was high (I²), our results using a sensitivity analysis showed robustness and reliability of the findings. People living in low-middle-income areas are more likely to develop Hashimoto's thyroiditis, while the group in high-income areas are more likely to develop Hashimoto's thyroiditis than people in upper-middle-income areas, and women's risk is about four times higher than men's.

Conclusions

Global Hashimoto's thyroiditis patients are about four times as many as males, and there are discrepancies in the regions with different economic levels. In low-middle-income areas with a higher prevalence of Hashimoto's thyroiditis, especially countries in Africa, therefore local health departments should take strategic measures to prevent, detect, and treat Hashimoto's thyroiditis. At the same time, the hidden medical burden other diseases caused by Hashimoto's thyroiditis should also be done well.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD 42022339839.

Role of papillary thyroid carcinoma patients with Hashimoto thyroiditis: evaluation of oxidative stress and inflammatory markers

PURPOSE

Papillary thyroid carcinoma (PTC) is the most frequent subtype of thyroid cancer; Hashimoto's thyroiditis (HT), autoimmune disease, commonly affects the thyroid gland; there is possibly a correlation between both, but the exact mechanisms that involve this relationship are still under debate. Since oxidative stress (OS) and the inflammatory environment participate in the development of several types of cancer, the objective of the present study was to establish the microenvironment and systemic participation of OS and inflammatory markers in patients with PTC and HT.

METHODS

Blood and tissue samples were collected from 115 patients: BENIGN (n = 63); PTC (n = 27); HT (n = 15) and PTC + HT (n = 10), and sixty-three were samples from healthy individuals (control group).

RESULTS

Superoxide dismutase, Catalase, reduced Glutathione, markers of lipid peroxidation and inflammation were evaluated in blood. Immunohistochemistry was performed on 3-nitrotyrosine, 4-hydroxynonenal, Ki-67 and VEGF. The results indicate that antioxidant enzymes were more active in groups with thyroid disorders compared to control, while the concentration of Reduced glutathione was reduced in BENIGN and PTC groups. When PTC and PTC + HT groups were analyzed, no significant differences were found in relation to the antioxidant defense and inflammatory markers. The ability to contain the induced lipid peroxidation was lower and a high level of malondialdehyde was observed in the PTC group. All immunohistochemical markers had higher scores in the PTC group compared to PTC + HT.

CONCLUSION

There was a more pronounced presence of OS and a greater activity of cell proliferation and angiogenesis markers in PTC than in PTC + HT group.

Thyroid autoimmunity in Greenlandic Inuit

Objective

This study aimed to provide the first data on the occurrence of thyroid autoimmunity among Inuit in Greenland, a distinct ethnic group who is not iodine deficient.

Design

This study is a population-based cross-sectional study.

Methods

Data were collected in Nuuk in West Greenland and in Ammassalik district in East Greenland. Information on lifestyle, diet and diseases was obtained using questionnaires. Thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TGAb) and thyroid-stimulating hormone (TSH) were measured in serum. Iodine and creatinine were measured in spot urine samples.

Results

The participation rate was 95% with 434 Inuit participants; 75% were smokers. Iodine excretion was 169 µg/24 h in urban West Greenland, 224 µg/24 h in the main town and 228 µg/24 h in settlements in rural East Greenland. TPOAb, TgAb or either of these was measured in the serum from 3.7, 5.9 and 8.3% of participants, respectively. TPOAb or TgAb was found in 9.3% of Inuit women and 7.5% of men and more frequently, in East Greenland Inuit with the higher iodine excretion (P = 0.02). There was some evidence suggesting that thyroid autoimmunity was more frequent among non-smokers (12.5%) compared to smokers (7.0%). Harbouring a thyroid autoantibody was most frequent in participants with TSH above 3.6 mIU/L (P < 0.001).

Conclusion

Thyroid autoantibodies were rare among Greenland Inuit. While iodine nutrition was associated with autoimmunity similarly to other ethnic groups, the influence of sex and smoking was limited. This could suggest genetic component in Inuit, but the impact of cold, selenium and persistent organic pollutants needs to be elucidated.

Impact of urinary iodine concentration on blood glucose levels and blood pressure: a nationwide population-based study

PURPOSE

Iodine is a vital trace element for systemic metabolic control as well as thyroid hormone synthesis. Though iodine has significant antioxidant and anti-inflammatory effects, reports on its effects on metabolic disorders are limited and inconsistent.

METHODS

Impact of urinary iodine concentrations (UICs) on fasting blood glucose (FBG) levels and blood pressure (BP) in the general Korean population was evaluated adjusting for covariates including thyrotropin level and presence of thyroid diseases.

RESULTS

The median UIC was 302.3 μg/L in all participants and was significantly lower in those with dysglycemia (303.6 μg/L in normal participants, 285.1 μg/L in participants with FBG levels of 100-125 mg/dL, and 261.8 μg/L in participants with FBG levels ≥ 126 mg/dL; p = 0.002). Similarly, the UIC was lower in participants with higher BP (311.6 μg/L in normal participants, 288.7 μg/L in prehypertensive participants, and 265.8 μg/L in hypertensive participants; p < 0.001). The multiple linear regression model showed a negative correlation between the UIC and FBG levels (p = 0.002), and the UIC and systolic BP (p < 0.001). One standard deviation increase in the UIC showed odds ratios of 0.84 (95% confidence interval [CI] = 0.73-0.98) for elevated FBG levels (≥ 100 mg/dL) and 0.94 (95% CI = 0.88-0.99) for elevated SBP (≥ 120 mm Hg) after full adjustment.

CONCLUSION

Higher UICs were associated with lower FBG and BP levels, independent of thyroid function and other confounding factors in Korea, an iodine-replete country.

Role of Dietary Supplements in Thyroid Diseases

BACKGROUND

Thyroid hormones play a vital role in regulating our body's metabolism. Two important thyroid hormones released from the thyroid gland are- tri-iodothyronine (T3) and tetra-iodothyronine (T4). Thyroid stimulating hormone and thyroid regulating hormone control the T3 and T4 levels in our body. Increased TSH levels indicate hypothyroidism and decreased TSH levels indicate hyperthyroidism. Iodine is a crucial nutrient for the synthesis of thyroid hormones and is mostly obtained from our diet. Other essential nutrients for the thyroid hormones formation include selenium, iron, vitamin D, vitamin B12, etc. Dietary changes in these nutrients can result in alterations in thyroid function and structure. Although, normally the hormonal diseases cannot be cured but we can improve their signs and symptoms using suitable dietary supplements.

OBJECTIVE

To thoroughly analyze the various benefits and risks associated with the use of dietary supplements for the prevention and treatment of various thyroid disorders, like hypothyroidism, as seen in hashimoto's thyroiditis; hyperthyroidism, as seen in grave's disease, sick euthyroidism and subclinical hypothyroidism.

METHODS

Literature was searched using the search terms; "dietary supplements+ thyroid diseases" on pub med, google scholar, scopus, cochrane library and other search engines and data was collected from 1967- November 2021 including research inputs from the authors. The literature was thoroughly read and deep knowledge was acquired on this topic, which was then sequentially organized and summarized using suitable tables and figures.

CONCLUSION

After analyzing the various studies on this topic we arrived at the conclusion that although, there are various claimed and observed health benefits of dietary supplements in prevention and treatment of various thyroid disorders; but still several studies have shown that, there are many risks associated too with the use of dietary supplements, and people using these products should be aware of these risks in order to use them very judiciously for the improvement of their thyroid status.

Effect of the transition from more than adequate iodine to adequate iodine on national changes in the prevalence of thyroid disorders: repeat national cross-sectional surveys in China

OBJECTIVE

Longitudinal studies have investigated the effects of changing iodine status on thyroid disorders, but the effect of a transition from more than adequate iodine to adequate iodine on national changes in prevalence adjusted for changing risk factors remains unclear.

DESIGN

Two repeat nationwide surveys were conducted from 2009-2010 to 2015-2017 to assess changes in thyroid disorder prevalence and iodine status in China.

METHODS

A multistage stratified random sampling method was used to obtain a nationally representative sample of urban adults aged 18 and older in mainland China in 2009 (n = 14 925) and 2015 (n = 12 553). Changes in thyroid disorder prevalence, urinary iodine concentration (UIC), and thyroid-stimulating hormone (TSH) levels were assessed. Logistic regression models were used to examine changes in prevalence over time.

RESULTS

The median UIC decreased significantly from 219.7 to 175.9 μg/L (P < 0.0001). The weighted prevalence of overt hyperthyroidism, subclinical hyperthyroidism, Graves' disease, and goitre decreased between 2009 and 2015 in the overall population (P < 0.05 for all). Despite no significant changes in subclinical hyperthyroidism or hypothyroidism or anti-thyroid peroxidase or anti-thyroglobulin antibody positivity prevalence, a significant increase in thyroid nodule prevalence (P < 0.0001) was found in the overall population. The 2.5th TSH percentile increased by 0.15 mIU/L (95% CI: 0.01 to 0.30 mIU/L, P = 0.04) from 2009 to 2015.

CONCLUSIONS

With the iodine status transition from more than adequate to adequate, thyroid disorder (except for thyroid nodules) prevalence remained stable or even decreased after adjusting for confounding factors among adults in mainland China between 2009 and 2015. Additional studies are needed to explore the reasons for the increased thyroid nodule prevalence.

The Characteristics of Iodine Nutrition Status in China After 20 Years of Universal Salt Iodization: An Epidemiology Study Covering 31 Provinces

Background: Despite the implementation of the universal salt iodization (USI) program for correction of iodine deficiency in China for ∼20 years, the actual iodine nutrition status of Chinese residents and the prevalence of iodine deficiency and iodine excess are issues that need to be addressed. This nationally representative cross-sectional study was conducted across all 31 provinces of mainland China to gather extensive data on iodine nutrition status and the influential factors. Methods: This study included 78,470 participants, aged 18 years or older, who were interviewed and asked to answer a questionnaire. Urine iodine concentration (UIC) was measured by the inductively coupled plasma mass spectrometry method, and goiter was examined by thyroid ultrasonography. In addition, sixty 9-11 years old school children in each province were randomly selected to evaluate the UIC and thyroid ultrasonography. The iodine nutrition status was determined according to the World Health Organization guidelines. Results: The iodized salt coverage was 95.37%. The median urine iodine (MUI) was 177.89 μg/L (interquartile range [IQR], 117.89-263.90 μg/L) and goiter prevalence was 1.17% (confidence interval [95% CI 0.95-1.43]) in the adult population. The MUI was 199.75 μg/L (IQR, 128.41-303.37 μg/L) in school-age children, and goiter prevalence was 3.50% [95% CI, 2.93-4.13]. The percentage of individuals with UIC <50 μg/L was 3.43%, <20%. Analysis indicated that sex, age, geographic factors, body mass index, and smoking habits influence the iodine nutrition level. Conclusion: The mandatory USI program has successfully eliminated iodine deficiency disorders, and the findings indicate that the iodine nutrition level in the general population is within the safe range.

Postpartum Thyroid Dysfunction in Women With Known and Newly Diagnosed Hypothyroidism in Early Pregnancy

Background

Hypothyroidism in the first trimester of pregnancy (T1) has great adverse effects on mothers and foetuses. However, few studies have investigated the influence on postpartum thyroid dysfunction. This study aimed to evaluate their long-term effect on postpartum thyroid function within one year after delivery.

Methods

In total, 151 women were recruited from 1496 participants and were classified as newly diagnosed subclinical hypothyroidism (SCH) in T1 (ND-SCH, n=50), previously known SCH before pregnancy (PK-SCH, n=51) and previously known overt hypothyroidism (PK-OH, n=50). Their thyroid functions were dynamically monitored from pre-conception to one-year postpartum.

Results

During pregnancy, the first thyroid functions' test time in T1 were 5-8 gestational weeks. After delivery, the prevalence of postpartum thyroiditis (PPT) was comparable in women with previously known and newly diagnosed hypothyroidism [ND-SCH 62.0% vs PK-SCH 64.7% vs PK-OH 64.0%, P=0.96]. For the ND-SCH group, PPT was significantly related with thyroid-stimulating hormone (TSH) >4.0 mU/L occurring at <8 gestational weeks [OR=8.06, 95% CI, 2.08-31.29] and TSH levels outside 1.0-2.5 mU/L near childbirth [OR=3.73, 95% CI, 1.04-13.41]. For patients with known hypothyroidism before pregnancy (PK-SCH and PK-OH), TSH>2.5 mU/L in T1 [OR=3.55, 95% CI, 1.43-8.81] and TPOAb≥300 μIU/mL [OR=6.58, 95% CI, 2.05-21.12] were associated with PPT. Regardless of whether SCH was diagnosed before pregnancy or in T1, the levothyroxine (LT4) treatment was discontinued at delivery. More than 50% of the patients had to face the hypothyroidism phase of postpartum and restarted LT4 treatment in the first-year follow-up. The logistic regression analysis revealed that TSH elevation occurring at <8 gestational weeks [OR=2.48, 95% CI, 1.09-5.6], TSH levels outside 1.0-2.5 mU/L near childbirth [OR=3.42, 95% CI, 1.45-8.05], and TPOAb≥300 μIU/mL [OR=6.59, 95% CI, 1.79-24.30] were the risk factors.

Conclusion

TSH elevation at <8 gestational weeks was associated with PPT after delivery in women with known and newly diagnosed hypothyroidism. Especially for SCH patients who stopped LT4 treatment at delivery, unsatisfactory TSH level at <8 gestational weeks and near childbirth, TPOAb≥300 μIU/mL were the risk factors for LT4 retreatment in one-year postpartum.

The association between subclinical hypothyroidism and metabolic syndrome: an update meta-analysis of observational studies

The association between subclinical hypothyroidism (SCH) and metabolic syndrome (MetS) has been widely discussed. This study aimed to conduct an update and comprehensive meta-analysis to reveal the risk of MetS and its components in SCH. PubMed, Embase and ISI Web of Knowledge were searched to identify relevant studies through February 20^th, 2020. Review Manager 5.3 and Stata 14.0 were used to conduct the meta-analysis. Both fixed-effects and random-effects models were used. In total, 18 articles (19 studies) incorporating 79,727 participants were included. The pooled OR for MetS comparing subjects with SCH with euthyroid subjects was 1.28 (95% CI: 1.19 to 1.39, p = 0.04, I² = 40%). Subgroup analysis results showed significant associations of SCH and MetS in the adult subgroup (OR = 1.28, 95% CI: 1.18-1.40), Asian population subgroup (OR = 1.30, 95% CI: 1.19-1.42) and cross-sectional study design subgroup (OR = 1.31, 95% CI: 1.16-1.47). Significant associations of SCH and MetS also existed in all MetS definition criteria subgroups except the Chinese Diabetes Society (CDS) subgroup. SCH was correlated with MetS and was not affected by the subgroup analysis stratified by the proportion of females in the total population, the TSH cutoff value in SCH diagnostic criteria, or the adjustment for confounding factors. SCH was identified to be associated with an increased risk of obesity, hypertension, high triglyceride (TG) levels and low high-density lipoprotein cholesterol (HDL-C) levels. In conclusion, SCH is significantly associated with an increased risk of MetS and four out of five components of MetS.

Iodine nutrition optimization: are there risks for thyroid autoimmunity?

Iodine deficiency is still the main cause of preventable thyroid disorders, worldwide. To optimize iodine intake, programs of voluntary or mandatory iodization of salt have been implemented in several iodine-deficient countries and iodine sufficiency has been achieved in many. Despite the clear beneficial effects on thyroid health, some concerns have been raised on the presumed detriment of iodine prophylaxis on thyroid autoimmunity. Very recent studies aimed at evaluating the long-term consequences of iodine supplementation on thyroid autoimmunity and related dysfunction, have clearly demonstrated that the early post-iodization increase in thyroid antibody positivity is largely transient and not clinically relevant, since the prevalence of overt thyroid dysfunction has remained reassuring low over two decades. The recommended iodine intake is therefore safe with regard to thyroid autoimmunity, the benefits largely outweighing the risks in a population with a stable median iodine concentration not exceeding 300 μg/L. Thus, a possible increase in thyroid autoimmunity should not represent a limitation to promoting iodine supplementation in the general population, also taking into account the steady rise in prevalence of autoimmune disorders which has occurred in the last few decades because of environmental factors other than iodine.

Familial Risk of Hashimoto's Thyroiditis Among First-Degree Relatives: A Population-Based Study in Korea

Background: Few small-scale studies have reported a genetic and familial predisposition in Hashimoto's thyroiditis (HT), however, quantified familial risk estimates from population-level data are unavailable. We aimed to estimate the incidence and familial risk of HT among first-degree relatives (FDR) according to age, sex, and family relationships. Methods: We conducted a population-based study in the general population of Korea from 2002 to 2017. Using the nationwide health insurance database, which has full population coverage and family relationship information, a cohort of 22 million individuals with blood-related FDR comprising 12 million families were followed up for a familial occurrence of HT. Age- and sex-adjusted incidence risk ratios (IRRs) were calculated in individuals with an affected FDR compared with those without an affected FDR. Results: Among 21,940,795 individuals, 234,912 had an HT-affected FDR, of whom 2425 familial cases developed HT with an incidence of 7.12/10,000 person-years. The familial risk for HT was 6.5-fold (95% confidence interval [CI]: 6.24-6.78) higher in individuals with versus without affected FDR. According to relationship, familial risks were IRR 102.71, IRR 7.80, IRR 5.54, and IRR 5.52 with an affected twin, sibling, mother, and father, respectively, and the corresponding incidence (/10,000 person-years) was 115.57, 10.66, 5.73, and 5.91. Same-sex twins had three times higher risk of developing HT than opposite-sex twins (IRR 121.01 vs. 21.46). The sex-specific familial risk was higher in males than females. The risks demonstrated age dependence, being higher in younger age groups. Conclusions: This study represents the largest population-based study of familial HT risk in Asia. We demonstrated elevated familial risk of incident HT among FDR, but with lower magnitude as those observed in previous studies. Familial risk increased with the degree of genetic relatedness among FDR indicating a prominent role of genetic factors in the familial aggregation of HT. Elevated risks in the younger age groups should motivate clinicians to screen people with a family history, especially those <30 years.

Thyroid Autoimmunity and Dysfunction in Sri Lankan Children and Adolescents After 22 Years of Sustained Universal Salt Iodization

Background: Sri Lanka introduced universal salt iodization (USI) in 1995 after which we demonstrated a high thyroglobulin antibody (TgAb) prevalence in 1998. However, it is unclear whether thyroid autoimmunity persists in the long term in populations exposed to sustained USI and whether such populations have an excess of thyroid dysfunction. We evaluated the prevalence of thyroid autoantibodies and dysfunction in Sri Lankan children and adolescents after more than two decades of sustained USI. Methods: We selected 10- to 18-year-old subjects of both sexes (randomized cluster sampling) from all 9 provinces of Sri Lanka in this cross-sectional study. Blood, urine, and anthropometric data were collected and thyroid ultrasound scans were performed. Validated statistical methods were used to derive local population-specific reference ranges for all thyroid parameters. We also measured urine iodine concentration (UIC), salt, and water iodine concentrations. Results: Blood and urine samples from 2507 and 2473 subjects respectively, and ultrasound scans from 882 subjects were analyzed. Population-derived upper limits for thyroid peroxidase antibody (TPOAb) and TgAb, and reference ranges for triiodothyronine, thyroxine, and thyrotropin (total and age-year-related groups) were significantly different from manufacturer's reference ranges. Using these derived ranges, the prevalence of TPOAb was 10.3% and TgAb was 6.4%. Of the TPOAb-positive subjects, TPOAb were of low concentration in 66.2% (1-3 times the upper limit of the reference range [ULRR]) and showed the strongest association with subclinical hypothyroidism (SCH) at the highest concentrations (>4 ULRR). The prevalence of SCH was 3%. Median UIC (interquartile range) was 138.5 μg/L (79.4-219.0) with regional variability, and median thyroglobulin was 8.3 ng/mL (4.1-13.5). Goiter prevalence was 0.6% and 1.93% (thyroid volume compared to age and body surface area, respectively). Salt and water iodine concentrations were satisfactory. Conclusions: Sri Lanka has safely and effectively implemented USI with good sources of iodine, leading to sustained iodine sufficiency over more than two decades. The early postiodization TgAb surge (42.1%) has settled (6.4%), and despite a persistently high TPOAb prevalence (10.3%), SCH prevalence remains low (3%). Further studies should be undertaken to monitor thyroid autoimmune dysfunction in Sri Lankan children, using age-specific, population-derived reference ranges.

In Vivo Inhibition of MicroRNA-326 in a NOD.H-2h4 Mouse Model of Autoimmune Thyroiditis

Background

Previous studies reported that various miRNAs participate in autoimmune diseases, but the potential regulatory mechanism of miRNAs in autoimmune thyroiditis (AIT) needs further exploration.

Objective

This study aimed to further verify that miR-326 contributes to AIT by regulating Th17/Treg balance through Ets-1 using lentiviral gene delivery through tail vein and thyroid injection in NOD.H-2^h4 mice.

Materials and Methods

Five-week-old NOD.H-2^h4 mice were divided randomly into tail vein and thyroid injection groups, and each received either mmu-miR-326 sponge (LV-sponge) or lentiviral vector control. Mice were divided for tail vein injection: the therapeutic LV-ctrl, therapeutic LV-sponge, prophylactic LV-ctrl, and prophylactic LV-sponge groups. The control group was fed high-iodine water without vein injection. The thyroid infiltration of lymphocytes and serum TgAb value were investigated by thyroid hematoxylin and eosin (HE) staining and ELISA, respectively. Ets-1 and lymphocyte counts were measured by RT-PCR, western blotting, and flow cytometry. The thyroid CD4⁺IL-17a⁺ cells and CD4⁺Ets-1⁺ cells were detected by immunofluorescence, and the serum cytokines were tested by ELISA.

Results

In the tail vein injection groups, the thyroid inflammatory score and serum TgAb titer were significantly lower in the LV-sponge groups than in the control and LV-ctrl groups while Ets-1 protein expression in mouse spleens was increased in the LV-sponge groups. Moreover, Th17/Treg ratio declined in the LV-sponge group and decreased significantly in the prophylactic LV-sponge group (P = 0.036) tested by flow cytometry. Immunofluorescence showed that, in LV-sponge groups, CD4⁺IL-17a⁺ cells were decreased significantly (P = 0.001), while CD4⁺Ets-1⁺ cells were increased significantly in the LV-sponge group (P = 0.029). The serum IL-17/IL-10 was decreased significantly in the LV-sponge group (P < 0.05). In the thyroid injection groups, the thyroid inflammatory score and serum TgAb titer in the LV-sponge group decreased significantly compared with those in the LV-ctrl group (P < 0.05). In addition, in LV-sponge groups, CD4⁺IL-17a⁺ cells were decreased, while CD4⁺Ets-1⁺ cells were increased significantly in the inhibition group evaluated by immunofluorescence. Moreover, tail vein injection of LV-sponge resulted in much lower TgAb levels in thyroiditis compared with thyroid injection.

Conclusion

MiR-326 targeted therapy may be a promising approach for AIT. In addition, tail vein injection may achieve a better intervention effect than thyroid injection.

Lifestyle is associated with thyroid function in subclinical hypothyroidism: a cross-sectional study

BACKGROUND

Few studies have focused on the association between lifestyle and subclinical hypothyroidism (SCH). The purpose of this study was to investigate the association between lifestyle and thyroid function in SCH.

METHODS

This study was a part of a community-based and cross-sectional study, the Epidemiological Survey of Thyroid Diseases in Fujian Province, China. A total of 159 participants with SCH (81 males and 78 females) and 159 euthyroid (87 males and 72 females) participants without any missing data were included in the analysis. General information and lifestyle information including sleep, exercise, diet and smoking habits of the participants was collected by questionnaire and Pittsburgh sleep quality index scale (PSQI) was collected. Thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroid peroxidase antibody (TPOAb), thyroid globulin antibody (TgAb) and urine iodine concentration (UIC) were tested. Thyroid homeostasis parameter thyroid' s secretory capacity (SPINA-GT), Jostel's TSH index (TSHI), thyrotroph T4 sensitivity index (TTSI) were calculated. Logistic regression and multiple linear regression were performed to assess associations.

RESULTS

Compared with euthyroid subjects, patients with SCH were more likely to have poor overall sleep quality (15.1 vs.25.8 %, P = 0.018) and l less likely to stay up late on weekdays (54.7 vs. 23.9 % P < 0.001). In SCH group, exercise was the influencing factor of TSH (β= -0.224, P = 0.004), thyroid secretory capacity (β = 0.244, P = 0.006) and thyrotropin resistance (β = 0.206, P = 0.009). Iodine excess was the influencing factor of thyroid secretory capacity (β = 0.209, P = 0.001) and pituitary thyroid stimulating function (β = 0.167, P = 0.034). Smoking was the influencing factor of pituitary thyroid stimulating function (β = 0.161, P = 0.040). Staying up late on weekends was the influencing factor of thyroid secretory capacity (β = 0.151, P = 0.047). After adjusting for possible confounders, logistic regression showed that those with poor overall sleep quality assessed by PSQI and iodine excess had an increased risk of SCH (OR 2.159, 95 %CI 1.186-3.928, P = 0.012 and OR 2.119, 95 %CI 1.008-4.456, P = 0.048, respectively).

CONCLUSIONS

Lifestyle including sleep, smoking, diet and exercise was closely related to thyroid function especially thyroid homeostasis in SCH.

Obesity and Monitoring Iodine Nutritional Status in Schoolchildren: is Body Mass Index a Factor to Consider?

Background: The frequency of overweight (OW) and obese (OB) children has increased worldwide, particularly in economically developed countries. No studies have been conducted to verify whether the increasing frequency of OW and obesity in schoolchildren may affect the evaluation of iodine nutritional status in populations. The aim of this study was to verify whether urinary iodine concentration (UIC), thyroid volume (TV), and thyroid hypoechoic pattern may be affected by body mass index (BMI) in schoolchildren. Methods: The children included in this study (aged 11-13 years) were a part of the schoolchildren recruited in the second nationwide survey (period 2015-2019) conducted in Italy to monitor by law (Atto di Intesa Stato-Regioni February 26, 2009) the nationwide iodine prophylaxis program. Specifically, 1281 schoolchildren residing in iodine-sufficient areas (IS group) and 384 children residing in a still mildly iodine-deficient area (ID group) were recruited between January and March 2015 in the first-degree secondary state schools. In all the children, spot UIC was measured, thyroid ultrasound was performed to evaluate TV, and hypoechogenicity was assessed to indirectly evaluate iodine-associated thyroid autoimmunity. Results: The frequency of OW, OB, and adequate weight (AW) children was similar in the IS and ID groups at any age. After adjusting for sex and age, the regression analysis showed lower UIC values in OB children than in AW children of the IS group (beta coefficient = -34.09 [95% confidence interval -65.3 to -2.8]), whereas no significant differences were observed in the ID group. In both the IS and ID groups, the distribution of TV in AW children was significantly shifted toward lower values in comparison to the distribution of OB children (p < 0.001 in the IS group; p = 0.012 in the ID group). Furthermore, the frequency of thyroid hypoechogenicity was higher in the ID group than in the IS group (10.9% vs. 6.6%, p = 0.005); however, in both groups, it was significantly lower in AW children than in OB children (p < 0.01). Conclusions: This study for the first time demonstrates that BMI may be a confounding factor in monitoring iodine nutritional status in schoolchildren. Since in Italy as in other Western countries the number of OW and OB children is high, BMI is a factor to consider in monitoring salt iodization programs worldwide.

Iodoprophylaxis and thyroid autoimmunity: an update

Adequate iodine intake is necessary for normal thyroid function. Iodine deficiency is associated with serious complications, but also iodine excess can lead to thyroid dysfunction, and iodine supplementation aimed to prevent iodine deficiency disorders has been associated with development of thyroid autoimmunity. The epidemiology of thyroid diseases has undergone profound changes since the implementation of iodoprophylaxis, notably by means of iodine-enriched salt, specifically resulting in decreased prevalence of goiter and neonatal hypothyroidism, improved cognitive function development in infancy, and reduced incidence of more aggressive forms of thyroid cancer. The main question we address with this review is the clinical relevance of the possible effect on autoimmunity exerted by the use of iodine-enriched salt to correct iodine deficiency. In animal models, exogenous iodine is able to trigger or exacerbate thyroid autoimmunity, but it is still not clear whether the observed immunological changes are due to a direct effect of iodine on immune response, or whether they represent a secondary response to a toxic effect of iodine on thyroid tissue. Previous iodine status of a population seems to influence the functional thyroid response to increased iodine intake and possibly the development of thyroid autoimmunity. Moreover, the prevalence of thyroid antibodies, regarded as hallmark of autoimmune thyroid disease, varies between populations under the influence of genetic and environmental factors, and the presence of thyroid antibodies does not always coincide with the presence of thyroid disease or its future development. In addition, the incidence of autoimmune diseases shows a general increasing trend in the last decades. For all these reasons, available data are quite heterogeneous and difficult to analyze and compare. In conclusion, available data from long-term population surveys show that a higher than adequate population iodine intake due to a poorly controlled program of iodine prophylaxis could induce thyroid dysfunction, including thyroid autoimmunity mostly represented by euthyroid or subclinical hypothyroid autoimmune thyroiditis. Close monitoring iodine prophylaxis is therefore advised to ensure that effects of both iodine deficiency and iodine excess are avoided.

Effect of selenium on thyroid autoimmunity and regulatory T cells in patients with Hashimoto's thyroiditis: A prospective randomized-controlled trial

Selenium (Se) is an essential trace element in human. Recent studies of Se supplementation on the effect of Hashimoto's thyroiditis (HT) have been reported, but the exact benefit is unclear as well as the underlying immunologic mechanism. We aimed to evaluate the clinical effect of Se supplement in patients with HT, and explore the potential mechanism against thyroid autoimmunity. A prospective, randomized-controlled study was performed in patients with HT assigned to two groups. Se-treated group (n = 43) received selenious yeast tablet (SYT) for 6 months, whereas no treatment in control group (n = 47). The primary outcome is the change of thyroid peroxidase antibody (TPOAb) or thyroglobulin antibody (TGAb). Second, thyroid function, urinary iodine, Se, Glutathione peroxidase3 (GPx3), and Selenoprotein P1 (SePP1) levels were measured during the SYT treatment. Meanwhile, regulatory T cells (Tregs) and their subsets activated Tregs (aTregs), resting Tregs, and secreting Tregs, as well as Helios and PD-1 expression on these cells were also detected. The results showed that SYT treatment significantly decreased TPOAb, TGAb, and thyroid stimulating hormone (TSH) levels, accompanied with the increased Se, GPx3, and SePP1, compared with the control group. Subgroup analysis revealed that subclinical HT may benefit more from this treatment in the decrease of TSH levels by interaction test. Moreover, the percentage of aTregs, Helios/Tregs, and Helios/aTregs were significantly higher in the Se-treated group than control. In conclusion, Se supplementation may have a beneficial effect on thyroid autoantibodies and thyroid function by increasing the antioxidant activity and upregulating the activated Treg cells.

Blood pressure characteristics of subclinical hypothyroidism: an observation study combined with office blood pressure and 24-h ambulatory blood pressure

OBJECTIVE

To investigate the characteristics of blood pressure in subclinical hypothyroidism by combining office blood pressure and 24-h ambulatory blood pressure.

METHODS

A total of 3078 adults voluntarily participants were enrolled in this study between December 2017 and November 2019. Among 1431 of them who did not fit exclusion criteria, 104 patients were with subclinical hypothyroidism (S-HYPO group), and 1327 were euthyroid participants (euthyroid group). Office blood pressure measurement and 24-h ambulatory blood pressure monitoring were carried out to analyze the characteristics of blood pressure in subclinical hypothyroidism.

RESULTS

There was no statistical difference in office SBP and DBP between the S-HYPO group and the euthyroid group (P > 0.05). On the ambulatory blood pressure level, the daytime SBP, night-time SBP, night-time SBP, 24-h SBP and DBP in the S-HYPO group were significantly higher than those in the euthyroid group (P = 0.048, P = 0.002, P = 0.003, P = 0. 014, P = 0. 046, respectively), and the proportion of nondipper blood pressure in the S-HYPO group was higher than that in the euthyroid group. Comprehensive analysis of blood pressure inside and outside the joint clinic revealed that the S-HYPO group was independently related to sustained hypertension and masked hypertension but not to white-coat hypertension (P = 0.004, P = 0.002, P = 0.886, respectively). After adjusting for age, sex, BMI, and other confounding factors, the above differences were still statistically significant (P < 0.05).

CONCLUSION

The characteristics of blood pressure in subclinical hypothyroidism can be more accurately understood by combining office blood pressure and ambulatory blood pressure.

Acupuncture for Hashimoto thyroiditis: study protocol for a randomized controlled trial

BACKGROUND

The incidence rate of Hashimoto thyroiditis (HT) has gradually increased in recent years. There has been no specific etiological treatment for HT. Even though with normal level of thyroid hormone, the patients may still suffer from various clinical symptoms, such as anterior neck discomfort, fatigue, and mood swings, which seriously impair their quality of life. Acupuncture has long been used in the treatment of thyroid diseases, but there has been no related standardized clinical study as of today. This study aims to assess the feasibility, efficacy, and safety of acupuncture for HT.

METHODS

This is a randomized, black-controlled assessor-blinded pilot trial. A total of 60 patients will be recruited and divided into the experimental group (n = 30) or the control group (n = 30). The experimental group will undergo acupuncture therapy (penetration needling of Hand-Yangming meridian, PNHM) for 16 weeks, followed by a 16-week follow-up period, and the control group will first go through an observation period for 16 weeks, followed by a 16-week compensation PNHM therapy. The primary outcome will be the change of the concentrations of anti-thyroperoxidase antibodies (TPOAb), antithyroglobulin antibodies (TgAb), and thyroid hormone, including total thyroxine (FT₄), free thyroxine (FT₃), and thyroid-stimulating hormone (TSH). The secondary outcome measurements include the thyroid-related quality of life questionnaire short-form (ThyPRO-39), The Mos 36-item Short Form Health Survey (SF-36), and Hospital Anxiety and Depression Scale (HAD). Data collection will be performed before the start of the study (the baseline assessment) and at weeks 8, 16, 24, and 32.

DISCUSSION

The study is designed to assess the feasibility and effectiveness of PNHM in reducing the thyroid antibody level and improving the quality of life of HT patients with hypothyroidism or subclinical hypothyroidism. Results of this trial will assist further analyses on whether the acupuncture treatment can alleviate symptoms for patients with HT.

TRIAL REGISTRATION

Acupuncture-Moxibustion Clinical Trial Registry AMCTR-IOR-19000308 ( ChiCTR1900026830 ). Registered on 23 October 2019.

Reference Intervals for Serum Thyroid-Stimulating Hormone Based on a Recent Nationwide Cross-Sectional Study and Meta-Analysis

OBJECTIVE

The aim of our study was to compare the reference intervals (RIs) [median (2.5^th-97.5^th percentiles)] for thyroid-stimulating hormone (TSH) between subgroups stratified by ethnicity and iodine status in a global context.

DESIGN AND METHODS

Primary data were derived from a recently published cross-sectional study in mainland China. Secondary data were obtained from online databases. The RIs for TSH were calculated in the reference population according to the National Academy of Clinical Biochemistry (NACB) standard and in the disease-free population. A meta-analysis of ethnicity- and iodine status-specific TSH RIs was performed.

RESULTS

The primary data showed that the TSH RI (mU/L) in the disease-free population was 2.33 (0.67, 7.87), which is wider than the published RI [2.28 (0.74, 7.04)] in the reference population. The meta-analysis showed that whether in the reference or disease-free population, the RIs in Yellows were much higher than those in Caucasians. In the reference population, the median and 2.5^th percentile in the iodine-sufficient subgroup were both lower than the iodine-deficient or more-than-adequate subgroup, while the 97.5^th percentile showed a positive trend with increasing sufficiency of iodine. However, in the disease-free population, the iodine-sufficient subgroup had a lower median and 97.5^th percentile but higher 2.5^th percentile than the iodine-deficient subgroup.

CONCLUSION

Yellows have a higher TSH RI than Caucasians. In the reference population, both the median and 2.5^th percentile TSH in the iodine-sufficient population were the lowest among the different iodine status subgroups, while the 97.5^th percentile of TSH showed an upward trend with increasing iodine sufficiency.

Association between Urinary Iodine Concentration and Thyroid Nodules in Adults: A Cross-Sectional Study in China

BACKGROUND

Associations between iodine intake and thyroid nodules (TNs) were not consistent. We aimed to illustrate the relationship between urinary iodine concentration (UIC) and TNs.

METHODS

A total of 12,698 participants were enrolled in analysis. All of the participants filled out questionnaires and underwent physical examinations, laboratory tests, and thyroid ultrasonography. UIC, serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAb), and thyroglobulin antibodies (TgAb) were measured in the central laboratory.

RESULTS

The prevalence of TNs was 16.00%, and the median UIC was 206.1 μg/L. TNs and UIC were negatively related when UIC was less than 527 μg/L (adjusted OR = 0.87; 95% CI, 0.80, 0.94), and the relationship between UIC and TNs was not statistically significant when UIC was greater than 527 μg/L (adjusted OR = 1.25; 95% CI, 0.98, 1.60). In women, UIC was negatively associated with risk for TNs (adjusted OR 0.95; 95% CI, 0.91, 0.99).

CONCLUSION

The relationship between TNs and UIC differed between men and women. The risk of TNs decreased with the elevation of UIC in men when UIC was lower than 527 μg/L, while UIC and the presence of TNs were negatively correlated in women. In the future, cohort studies or other studies that can explain causality must be conducted to explore the relationship between iodine status and TNs.

The Effect of Increased Iodine Intake on Serum Thyrotropin: A Cross-Sectional, Chinese Nationwide Study

Background: Subclinical hypothyroidism is diagnosed based on serum thyrotropin (TSH) reference intervals, which in turn are affected by many factors. Methods: Data were acquired from a Chinese nationally representative cross-sectional study of 78,470 participants (TIDE study). The total study population were participants from the TIDE program, and the reference population was a subset of the total population defined by the National Academy of Clinical Biochemistry (NACB) guidelines. Serum concentrations of thyroid hormones, TSH, thyroid antibodies, and urine iodine concentration (UIC) were measured. Results: The geometric mean serum TSH (2.5th-97.5th) for the reference population (defined by the NACB) and total population was 2.28 mIU/L (0.74-7.04 mIU/L) and 2.34 mIU/L (0.61-8.33 mIU/L), respectively. In the reference population, increase in UIC was significantly associated with increase in the 50th and 97.5th centiles and decrease in the 2.5th centile of TSH. The median TSH was significantly higher in women than in men (2.41 mIU/L vs. 2.16 mIU/L, p-value <0.001). Increased age was significantly associated with an increased TSH, 97.5th centile. For each 10-year increase in the population age, the TSH 97.5th centile increased by 0.534 mIU/L. The prevalence of subclinical hypothyroidism diagnosed according to the assay-recommended interval (Roche 0.27-4.2 mIU/L) and NACB standard interval in the TIDE study (0.74-7.04 mIU/L) differed significantly (Roche 13.61% vs. TIDE 3.00%, p < 0.05). However, there was no significant difference in future cardiovascular disease, reflected by the Framingham risk score, between the 0.27-4.2 and 4.2-7.04 mIU/L TSH groups. Conclusions: Serum TSH concentration significantly increased with increase in iodine intake. Thus, iodine intake must be considered in establishing TSH reference intervals. To avoid overdiagnosis and overtreatment of subclinical hypothyroidism, different areas should use individual serum TSH reference intervals.

An Inverse Relationship Between Iodine Intake and Thyroid Antibodies: A National Cross-Sectional Survey in Mainland China

Background: Iodine intake is associated with thyroid autoimmunity. In this study, we evaluated the changes in thyroid autoimmunity after 20 years of universal salt iodization (USI) in China. Methods: A total of 78,470 subjects (18 years or older) from 31 provincial regions of mainland China participated in the study. Serum thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb), TSH receptor antibody, thyrotropin (TSH), and urinary iodine concentration (UIC) were measured. Results: Positive TPOAb and TgAb were detected in 10.19% [CI 9.80-10.59] and 9.70% [CI 9.28-10.13] of the subjects, respectively. The prevalence of positive isolated TPOAb (i-TPOAb), positive isolated TgAb (i-TgAb), and double positive TPOAb and TgAb (d-Ab) was 4.52%, 4.16%, and 5.94%, respectively. The prevalence of thyroid antibody positivity was the highest in the iodine-deficient (UIC <100 μg/L) groups. The prevalence of i-TPOAb was inversely associated with more than adequate iodine intake (MAI) and excessive iodine intake (EI); the odds ratio (OR) was 0.89 [CI 0.81-0.98] for MAI and 0.90 [CI 0.81-0.99] for EI. We observed that i-TgAb, like i-TPOAb, was a high-risk factor for subnormal TSH levels (OR = 3.64 [CI 2.62-5.05]) and elevated TSH levels (OR = 1.62 [CI 1.49-1.77]). The prevalence of thyroid antibody positivity varied among five ethnic groups. Conclusions: After two decades of USI, the prevalence of thyroid antibody positivity has remained low. MAI and EI had an inverse relationship with TPOAb positivity, which reveals that UIC between 100 and 299 μg/L is optimal and safe for thyroid autoimmunity. These conclusions need to be confirmed in a follow-up study because this study was a cross-sectional study.

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.

High prevalence of TPO-Abs and subclinical hypothyroidism in iodine-sufficient pregnant women in Northern Algeria

BACKGROUND

Iodine is a trace element whose adequate intakes are essential during gestation to promote the correct growth and development of the fetus. Historically, endemic goiter and cretinism affected northern regions of Algeria, and iodized salt was introduced in 1990. However, there has been no national study of iodine nutrition in Algeria since 1994. The aim of this study was to assess the iodine status and thyroid function of women of reproductive age (WRA) and pregnant women (PW) in northern Algeria.

METHODS

Healthy WRA and PW were recruited from an urban area (Algiers) and healthy WRA from a rural area (Tizi-Ouzou). Spot urine and venous blood samples were collected to assess iodine status (urinary iodine concentration, UIC) and serum thyroid hormones (TSH, FT4), thyroglobulin (Tg), and anti-thyroid peroxidase antibodies (TPO-Ab) concentrations.

RESULTS

The median UIC in WRA was 256 μg/L (IQR: 166-354 μg/L; n = 151) in Algiers and 253 μg/L (167-341 μg/L; n = 150) in Tizi-Ouzou. The median UIC for the PW in Algiers was 233 μg/L (IQR: 157-326 μg/L; n = 173).Thirty-five percent of WRA and 30% of PW had an UIC > 300 μg/L. Median TSH, FT4 and Tg concentrations were within reference ranges in all groups of women. Among PW, 72.7%, 75.4% and 75.5% in the first, second and third trimester were TPO-Ab+. Among TPO-Ab + PW in the first, second and third trimesters, 18.7%, 13% and 10.3% had subclinical hypothyroidism.

CONCLUSION

In northern Algeria, median UICs in PW indicate iodine sufficiency, and in WRA indicate more than adequate intakes. About 75% of PW are TPO-Ab + and the prevalence of subclinical hypothyroidism is high. Monitoring and surveillance of iodine fortification programs is vital to avoid both iodine deficiency and excess. There is an urgent need for a comprehensive national iodine status survey including school-age children and other vulnerable population groups in Algeria.

Iodine nutrition status and its association with microvascular complications in urban dwellers with type 2 diabetes

Background

The principal function of iodine acts on thyroid function, but in recent years, the role of iodine deficiency in metabolism has also been gradually revealed. We aimed to investigate the current status of iodized salt consumption and urinary iodine concentration (UIC) in an urban Chinese population with type 2 diabetes, and to further explore whether UIC was associated with diabetic microvascular complications.

Methods

Four thousand five hundred fifty-nine subjects with diabetes from 7 communities in downtown Shanghai were enrolled in the cross-sectional Metal Study in 2018. UIC was detected using an inductively coupled plasma-mass spectrometer. Diabetic kidney disease (DKD) was defined as urinary albumin-to-creatinine ratio (UACR) > 30 mg/g or estimated glomerular filtration rate < 60 mL/min/1.73 m². Diabetic retinopathy (DR) was evaluated by high-quality fundus photographs and was remotely read by ophthalmologist.

Results

The median UIC of subjects with diabetes was 115.4 μg/L (78.9–170.8) in downtown Shanghai. Among all the subjects, 52.7% consumed non-iodized salt and 40.4% were iodine deficient. Iodine deficiency (UIC < 100 μg/L) was associated with an increased odds of DKD (OR 1.17; 95%CI 1.01–1.37) after adjustment for age, sex, education, current smokers, BMI, HbA1c, duration of diabetes, dyslipidemia, thyroid-stimulating hormone and free thyroxine. No association was observed between UIC and DR after multivariable adjustment.

Conclusions

A concerning number of subjects with diabetes consumed non-iodized salt and suffered from iodine deficiency in coastal regions of China. Low UIC might be a risk factor for DKD, which should be further confirmed by longitudinal prospective studies.

Prevalence of thyroid dysfunction in healthy adults according to the estimated iodine intake in 24-hour urine samples: The SALMEX cohort

PURPOSE

The aim of this study was to evaluate the prevalence of thyroid dysfunction in a cohort of healthy individuals in Mexico City, as well as to investigate the potential associations of these results with their estimated iodine intake (EII) as reflected by their 24-hour urinary iodine excretion (24-h UIE).

METHODS

From the SALMEX cohort, 683 adults provided an appropriate 24-h urine sample. Thyroid function tests and thyroid antibody concentrations were determined in the participants' sera. We analyzed discrepancies between the commonly used urinary parameters to determine the iodine intake status and the performance of thyroglobulin (Tg) as a biomarker of its status in the adult population.

RESULTS

The prevalence of dysthyroidism was high, being similar to other studies. Subclinical hypothyroidism was detected in 5.0% of individuals, clinical hypothyroidism in 1.8% of individuals, and sub-clinical hyperthyroidism in 2.8% of individuals. The median EII was 285 μg/d (IQR 215.0-369.0); 94% of individuals had EII >150 µg/d recommended daily allowance (RDA) in adults. The urinary iodine concentration (UIC) and the UIE had relative biases in their averages of 34.4%. The Tg median was 7.21 ng/mL. The prevalence of increased Tg was 6.15%. There was no correlation between Tg and EII (r= 0.019, p= 0.606).

CONCLUSIONS

Thyroid dysfunction was highly prevalent in this population. Our cohort revealed a slight discrepancy between dysthyroidism manifestations and iodine intake markers; the latter represent a population with adequate iodine intake. Further studies are necessary to clearly define the prevalence of thyroid dysfunction as well as the iodine nutritional status in Mexico.

Intake of seaweed as part of a single sushi meal, iodine excretion and thyroid function in euthyroid subjects: a randomized dinner study

OBJECTIVE

Globalisation has extended to the kitchen and the Asian cuisine has gained international popularity with sushi and seaweed now being widespread. We explored the possible acute adverse effects of an iodine load from a single sushi-and-seaweed meal as seaweed iodine may induce thyroid dysfunction.

METHODS

Nine euthyroid participants were randomized into three groups: Halibut maki roll with either (A) newly harvested Greenlandic seaweed salad, (B) no seaweed salad on the side, or (C) Japanese seaweed salad purchased at a local store. We collected spot urine and blood samples daily for a week for measurement of iodine and creatinine in urine, thyroid stimulating hormone (TSH), and estimated-free T4 (fT4) in serum.

RESULTS

All participants ingested the full meal and the drop-out was nil. No adverse effects were reported. Pre-meal urinary iodine excretion (UIE) was 75 µg/g. UIE rose (p < 0.001) by 385%, 59% and 43% for groups A, B, and C, peaked in the 6-h spot urine sample at 393, 120, and 109 µg/g, and was down to pre-meal values by day 2. Serum TSH rose (p = 0.012) 150% on day 2 and was down to pre-meal values by day 3. Serum fT4 remained at the same level. No adverse reactions were reported.

CONCLUSION

A sushi meal increased urinary iodine excretion by 40 µg/g, or 400 µg/g if a newly harvested seaweed salad was added. An ensuing rise in serum TSH was brief, and a single sushi meal with seaweed salad did not cause any adverse events.

Prevalence and clinical correlates of subclinical hypothyroidism in first-episode drug-naive patients with major depressive disorder in a large sample of Chinese

BACKGROUND

The coexistence of subclinical hypothyroidism (SCH) and depression has been intensively examined in the patients receiving thyroxine or antidepressant treatment. This study aimed to investigate the prevalence and clinical correlates of severe SCH in Chinese first-episode drug naïve patients with major depressive disorder (MDD).

METHODS

Using a cross-sectional design, we recruited a total of 1706 MDD patients. Depressive symptoms were evaluated using the 17-item Hamilton Depression Rating Scale (HAMD). Severity of anxiety and psychiatric symptoms were evaluated by the Hamilton Anxiety Rating Scale (HAMA) and the Positive and Negative Syndrome Scale (PANSS), respectively. Serum thyroid function parameters were measured by a chemiluminescence immunoassay. Based on the serum thyroid stimulating hormone (TSH) level, SCH was further divided into mild (TSH < 10 mIU/L) and severe SCH (TSH ≥ 10 mIU/L).

RESULTS

More patients with severe SCH had severe anxiety, psychotic symptoms, suicide attempts (all p < 0.001), compared with those without severe SCH. Logistic regression showed that suicide attempts and psychiatric symptoms were associated with severe SCH (both p < 0.001). Multiple linear regression showed that age (p < 0.05), BMI (p < 0.001), HAMD score (p < 0.001), HAMA score (p < 0.001), PANSS positive subscore (p = 0.001) and CGI score (p = 0.001) were associated with TSH levels.

CONCLUSION

Our findings suggest that suicide attempts and psychiatric symptoms may be associated with severe SCH. Moreover, severe anxiety, depressive and psychotic symptoms, as well as older age and higher BMI are possibly related to elevated TSH levels.

Effects of Excessive Iodine Intake on Blood Glucose, Blood Pressure, and Blood Lipids in Adults

To understand the effects of excess iodine intake on blood glucose, blood pressure, and blood lipids in adults. We selected three villages from Shanxi Province to conduct cross-sectional survey: Maxi [median water iodine concentration (MWIC) 6.3 μg/L, median urinary iodine concentration (MUIC) 126.6 μg/L, 320 adults]; Xiwenzhuang (MWIC 79.8 μg/L, MUIC 221.2 μg/L, 264 adults); and Gaoche (MWIC 506.0 μg/L, MUIC 421.3 μg/L, 241 adults). According to the urinary iodine levels in adults, the three villages were defined as iodine-adequate, iodine-sufficient, and iodine-excess. Urinary iodine, water iodine, thyroid function, blood glucose, blood pressure, and blood lipids were measured. Compared with the iodine-adequate area, blood glucose and systolic and diastolic pressure of adults in iodine-sufficient and iodine-excess areas increased and high-density lipoprotein-cholesterol decreased (all P < 0.001). Urinary iodine, thyroid-stimulating hormone, and free thyroxine have a nonlinear correlation with blood glucose (R² = 0.8174, 0.8264, and 0.8520, respectively). Excessive iodine intake may result in elevated blood glucose and blood pressure and has some influence on blood lipids, and may increase the risk of hypertension and diabetes.

Thyroid hormone concentrations in second trimester of gestation and birth outcomes in Shanghai, China

BACKGROUND

Previous studies suggested that thyroid function in the first trimester of gestation played an important role in fetal growth. However, limited clinical data are available to support this relationship in the second trimester of gestation.

OBJECTIVE

We examined the relationship of maternal thyroid function parameters in early second trimester of gestation with birth outcomes in China.

METHODS

Participating 5016 mother-infant pairs were recruited from the Songjiang District Maternity and Infant Hospital, Shanghai, China, between July and December 2016. Linear regression assessed the associations of thyroid hormones with birthweight. Logistic regression tested the correlations between thyroid hormones and low birthweight, macrosomia, small for gestational age , and large for gestational age infants. Maternal serum TSH, TT3, TT4, FT3, and FT4 concentrations were measured in 16-20 weeks of gestation.

RESULTS

TT3 and FT3 were positively associated with birthweight, while TT4 and FT4 were negatively associated with birthweight, respectively. Furthermore, higher TT3 and FT3 were associated with increased risks of LGA infants (OR = 1.48, 95% CI: 1.15-1.9; OR = 1.22, 95% CI: 1.01-1.46), respectively. Higher TT3 was associated with an increased risk of macrosomic infants (OR = 1.35, 95% CI: 1.04-1.74). In contrast, higher FT4 was associated with decreased risks of LGA (OR = 0.87, 95% CI: 0.81-0.93) and macrosomic infants (OR = 0.90, 95% CI: 0.84-0.96), respectively. No associations were found between TSH and any of the outcomes.

CONCLUSIONS

TT3 and FT3 were positively associated with fetal growth, while TT4 and FT4 were negatively associated with fetal growth. Our findings suggested that thyroid function in early second trimester of gestation is a potential risk factor for abnormal fetal growth.

Association of antithyroglobulin antibody with iodine nutrition and thyroid dysfunction in Nepalese children

Background

Aberrant iodine intake and thyroid autoimmunity affect thyroid function. Deficiencies of iodine including thyroid disorders have serious impact on child physical and mental development. This study was conducted to investigate iodine nutrition, thyroid function and thyroid autoimmunity in the Nepalese children, and explore the association of thyroidal autoimmunity with iodine nutrition and thyroid dysfunction.

Methods

Five schools from Udayapur district of eastern Nepal were selected for the study. A total of 213 school children aged 6–12 years were enrolled, and anthropometric data, urine samples and blood samples were collected. Urinary iodine concentration (UIC), free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), and antithyroglobulin antibody (TgAb) was measured. Independent T test, Man-Whitney test, Chi-square test and Fisher’s Exact test were used for testing statistical significance. Spearman’s correlation analysis was done to find association between variables.

Results

The median UIC with IQR, mean ± SD fT3, mean ± SD fT4, median TSH and TgAb with IQR was 150.0 μg/L (102.8; 204.0), 2.49 ± 0.83 pg/ml, 1.33 ± 0.42 ng/dl, 2.49 mIU/L (1.58; 4.29), and 21.40 IU/ml (15.54; 31.20) respectively. Elvated TgAb (≥30 IU/ml, thyroid autoimmune condition) was seen in 25.8% (n = 55) children. UIC was less than 100 μg/L in 17.4% (n = 37) of the children. Subclinical hypothyroidism, overt hypothyroidism and sublinical hyperthyroidism was seen in 1.4% (n = 3), 3.3% (n = 7) and 3.8% (n = 8) children respectively. A strong association of TgAb with UIC (r = − 0.210, p = 0.002) and thyroid hormones; fT3 (r = − 0.160, p = 0.019), fT4 (r = − 0.275, p < 0.001), and TSH (r = 0.296, p < 0.001) was seen. The relative risk for thyroid autoimmunity in children with UIC less than 100 μg/L was 1.784 (95% CI: 1.108–2.871, p = 0.024). Similarly, children with thyroid autoimmunity had higher relative risk [7.469 (95% CI: 2.790–19.995, p < 0.001)] for thyroid dysfunction.

Conclusions

School children of eastern Nepal have adequate iodine nutrition. Thyroid autoimmunity is very common, while thyroid dysfunction is sparse in children. An association of thyroid autoimmunity with iodine nutrition and thyroid dysfunction was seen in children.