Genome-wide DNA methylation pattern in whole blood of patients with Hashimoto thyroiditis.

Background: Hashimoto thyroiditis (HT), a prevalent autoimmune disorder, is not yet thoroughly understood, especially when it comes to the influence of epigenetics in its pathogenesis. The primary goal of this research was to probe the DNAm profile across the genome in the whole blood derived from patients suffering from HT. Method: Using the Illumina 850K BeadChip, we conducted a genome-wide DNAm assessment on 10 matched pairs of HT sufferers and healthy individuals. Genes with differential methylation (DMGs) were identified and underwent functional annotation via the databases of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. The transcriptional significance of potential epigenetic biomarker genes was corroborated through qRT-PCR. Results: The DNAm profiling across the genome indicated an overall reduction in methylation in HT subjects in comparison with their healthy counterparts. We detected 283 DMPs (adjusted P < 0.05 and |Δß| > 0.1), among which 152 exhibited hypomethylation and 131 demonstrated hypermethylation. Further analysis exposed a noteworthy concentration of hypermethylated DMPs in the 3´UTR, North Shore, and CpG islands, while there was a significant decrease in the Open Sea (all P < 0.001). The 283 DMPs were broadly distributed from chromosome 1 to 22, with chromosome 6 harboring the most DMPs (n = 51) and chromosome 12 carrying the most DMGs (n = 15). The SLFN12 gene, which presented with extreme hypomethylation in its promoter DMPs among HT patients, was identified as the epigenetic marker gene. Consequently, the SLFN12 mRNA expression was markedly upregulated in HT, displaying a negative relationship with its methylation levels. The area under curve (AUC) value for the SLFN12 gene among HT patients was 0.85 (sensitivity: 0.7, specificity: 0.7), a significant difference compared with healthy controls. The methylation levels of all DMPs in SLFN12 gene were negatively correlated with TSH and one CpG site (cg24470734) was positively assocciated with FT4. Conclusion: This investigation presents an initial comprehensive DNAm blueprint for individuals with HT, which permits clear differentiation between HT subjects and normal controls through an epigenetic lens. The SLFN12 gene plays a pivotal role in the onset of HT, suggesting that the methylation status of this gene could serve as a potential epigenetic indicator for HT.

The whole blood DNA methylation of RAB8A and RAP1A in autoimmune thyroiditis: evidence and validation of iodine exposure in a population from different water iodine areas.

Our study aimed to identify and verify G protein-related methylated genes in AIT patients, while also investigate those genes in AIT patients exposed to iodine in different water iodine areas. Different areas were classified by median water iodine (MWI) concentrations: Iodine-Fortified Areas (IFA, MWI<10µg/L), Iodine-Adequate Areas (IAA, 40≤MWI≤100 µg/L), and Iodine-Excessive Areas (IEA, MWI>100 µg/L). We studied 176 AIT cases and 176 controls, with 89, 40, and 47 pairs in IFA, IAA, and IEA, respectively. Using the Illumina Human Methylation 850k BeadChip, we identified candidate methylated genes. MethylTargetTM and QRT-PCR validated DNA methylation and mRNA expression. Results showed hypomethylation and high expression of RAB8A and RAP1A in all 176 AIT cases. RAB8A's CpG sites were mainly hypomethylated in IFA and IEA, while RAP1A's sites were primarily hypomethylated in IEA. This study underscores how water iodine exposure may influence RAB8A and RAP1A methylation in AIT.

A study of programmed death-1/programmed death ligand and iodine-induced autoimmune thyroiditis in NOD.H-2h4 mice.

Excess iodine will trigger the occurrence of autoimmune thyroiditis (AIT), and programmed death-1 (PD-1)/programmed death ligand (PD-L) will also contribute to the development of AIT. The purpose of this study was to explore the role that negative regulatory signals mediated by PD-1/PD-L play in the development of spontaneous autoimmune thyroiditis (SAT) in NOD.H-2h4 mice when they are exposed to iodine. Programmed death ligand 1 (PD-L1) antibody was administered intraperitoneally to NOD.H-2h4 mice. The relevant indicators were determined by flow cytometry, real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, immunohistochemistry, pathological hematoxylin and eosin staining, and arsenic-cerium catalytic spectrophotometry. Results showed that the level of urinary iodine, the level of thyroid lymphocyte infiltration, the level of thyroglobulin antibodies (TgAb) and interferon (IFN-γ)/tumor necrosis factor (TNF-α)/interleukin (IL-2)/IL-17, and the relative expression of PD-1/PD-L1/programmed death-2 (PD-L2) increased with the intervention of excess iodine. After the intervention of the PD-L1 antibody, the expression of PD-1/PD-L1/PD-L2 in different degrees was inhibited, but the level of thyroid lymphocyte infiltration and serum TgAb/IFN-γ/TNF-α/ IL-2/IL-17 did not decrease. Collectively, although PD-1/PD-L participates in the occurrence of SAT and induces inflammation, administration of the PD-L1 antibody does not effectively improve the pathological process of SAT. More research is needed to determine whether PD-1/PD-L intervention can treat autoimmune thyroid disease.

Effects of different iodine levels on the DNA methylation of intrinsic apoptosis-associated genes and analysis of gene-environment interactions in patients with autoimmune thyroiditis.

Iodine is an essential nutrient that may change the occurrence of autoimmune thyroiditis (AIT). Apoptosis and DNA methylation participate in the pathogenesis and destructive mechanism of AIT. We detected the methylation and the expression of mRNA of intrinsic apoptosis-associated genes (YWHAG, ING4, BRSK2 and GJA1) to identify the potential interactions between the levels of methylation in these genes and different levels of iodine. 176 adult patients with AIT in Shandong Province, China, were included. The MethylTargetTM assay was used to verify the levels of methylation. We used PCR to detect the mRNA levels of the candidate genes. Interactions between methylation levels of the candidate genes and iodine levels were evaluated with multiplicative and addictive interaction models and GMDR. In the AIT group, YWHAG_1 and six CpG sites and BRSK2_1 and eight CpG sites were hypermethylated, whereas ING4_1 and one CpG site were hypomethylated. A negative correlation was found between methylation levels of YWHAG and mRNA expression. The combination of iodine fortification, YWHAG_1 hypermethylation and BRSK2_1 hypermethylation was significantly associated with elevated AIT risk. A four-locus model (YWHAG_1 × ING4_1 × BRSK2_1 × iodine level) was found to be the best model of the gene-environment interactions. We identified abnormal changes in the methylation status of YWHAG, ING4 and BRSK2 in patients with AIT in different iodine levels. Iodine fortification not only affected the methylation levels of YWHAG and BRSK2 but also interacted with the methylation levels of these genes and may ultimately increase the risk of AIT.

Relationship between mild iodine deficiency in pregnant women and thyroid function: A meta-analysis.

BACKGROUND: Pregnant women are among the key groups in iodine nutrition evaluation. The purpose of the present study was to summarize the evidence supporting the relationship between mild iodine deficiency (UIC: 100-150 µg/L) in pregnant women and levels of thyroid function tests. METHODS: This review follows the guidelines for systematic reviews (PRISMA 2020). Three electronic databases (PubMed, Medline, and Embase) were searched for relevant publications in English on the association between mild iodine deficiency in pregnant women and thyroid function. Articles published in Chinese were searched in China's electronic databases (CNKI, WanFang, CBM, and WeiPu). Pooled effects were presented as standardized mean differences (SMDs) and odds ratios (ORs) with 95% confidence intervals (CIs) using fixed or random effect models, respectively. This meta-analysis was registered at www.crd.york.ac.uk/prospero as CRD42019128120. RESULTS: We summarized the results from 7 articles with 8261 participants. The overall pooled results showed that the levels of FT3, FT4, and abnormal TgAb (the antibody levels exceeded the upper limit of the reference range) were significantly increased in pregnant women with mild iodine deficiency compared to pregnant women with adequate iodine status (FT3: SMD=0.854, 95% CI: 0.188, 1.520; FT4: SMD=0.550, 95% CI: 0.050, 1.051; TgAb: OR=1.292, 95% CI: 1.095; 1.524). Subgroup analysis was carried out on the sample size, ethnicity, country, and gestation of FT3, FT4, and TSH, but no plausible factor was found. Egger's tests indicated no publication bias.The increase in FT3 and FT4, as well as TgAb levels, in pregnant women is associated with mild iodine deficiency. CONCLUSION: Mild iodine deficiency is associated with an increase in FT3，FT4 and TgAb levels in pregnant women. Mild iodine deficiency may increase the risk of thyroid dysfunction in pregnant women.

Alteration of Lipid Profile Between Subclinical Hypothyroidism and Well-Matched Controls: A Meta-Analysis.

In previous studies, subclinical hypothyroidism (SCH) has been associated with altered lipid profiles. However, since the discrepancy between these study results may reside in the great heterogeneity of the populations studied, this relationship is controversial. This study aimed to explore the changes in total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) between subclinical hypothyroidism (SCH) and well-matched euthyroid (EU) groups. Multiple databases were searched for publications before December 1, 2021, including cross-sectional studies on the association between SCH and lipid profile matched by age, gender, and BMI. Twenty-five articles with 3347 participants were included for meta-analysis. The results showed that the TC, TG, and LDL-c levels of the SCH groups were higher than the EU groups (TC, SMD=0.49, 95% CI 0.27, 0.71, p<0.001) (TG, SMD=0.43, 95% CI 0.21, 0.64, p<0.05 ) (LDL-c, SMD=0.75, 95% CI 0.46, 1.03, p<0.001 ). The HDL-c levels of the SCH group were lower than the control group (SMD=-0.53, 95% CI -0.81, -0.25, p<0.05). SCH has a larger impact on LDL-c than the other three indicators. After subgroup analyses, there was a larger impact on lipid alteration in the subgroup of TSH>10 µIU/ml, especially on LDL-c. This study found that SCH was associated with altered lipid profiles. Appropriate clinical treatment may be needed to prevent dyslipidemia and related diseases.

The Thyroid Condition and Residual Clinical Signs in 31 Existing Endemic Neurological Cretins After 42 Years of Iodine Supplementation in China.

Backgroud: Endemic cretinism is the most severe manifestation among the iodine deficiency-related disorders. The clinical status of the cretins may be modified subsequently by the duration and severity of the disease. We aimed to reassess the clinical status and thyroid function of 31 surviving "neurological cretins" after 42 years of iodine supplementation in a historically severely iodine deficiency area of China. Methods: It was a cross-sectional study in design and we investigated all 31 surviving neurological cretins and 85 controls. A detailed neurological examination was conducted on each patients. All the participants were given a questionnaire and underwent B-mode ultrasonography of the thyroid. The serum levels of thyroid hormones, thyroid antibodies, serum iodine concentration (SIC) and urine iodine concentration (UIC) were measured. Results: The neurological cretins had shorter stature than that of the control. Neurological damage is still present in patients with cretinism. The prevalence of subclinical hypothyroidism and thyroid nodule in the cretins was significantly higher (χ2 =4.766, P=0.029 and χ2 =17.077, P<0.0001, respectively) compared with the control. After adjusting for confounding factors, endemic neurocretinism was found to be an independent risk factor for subclinical hypothyroidism (OR=4.412; 95% CI: 1.358-14.334; P=0.014) and thyroid nodule (OR=6.433; 95% CI: 2.323-17.816; P<0.0001). Conclusions: Iodine supplementation after birth does not reverse the neurological damage that results from maternal/foetal hypothyroidism in utero and is subsequently manifested as neurological cretinism. There is a cross-sectional association between endemic neurocretinism and subclinical hypothyroidism and thyroid nodule.

Relationships between the serum TPOAb and TGAb antibody distributions and water iodine concentrations, thyroid hormones and thyroid diseases: a cross-sectional study of 2503 adults in China.

The aim of this study was to explore the status of thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb) in three areas with differing water iodine concentrations; and to discuss the relationships between these two thyroid antibodies and thyroid diseases in the three areas. We investigated 2503 adults from three areas. Urinary iodine concentrations, thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), TPOAb, TGAb and thyroid volume (TV) were measured, and thyroid ultrasonography was performed. The positivity rates of TGAb(+), TPOAb(+) and TGAb(+) and TPOAb(+) or TGAb(+) were significantly higher in iodine fortification (IF) areas than iodine adequate (IA) areas (all P < 0·05). In IF and iodine excess areas, the positivity rates of TPOAb(+), TGAb(+) and TPOAb(+) or TGAb(+) significantly increased with age (all P for trend < 0·05). The levels of TSH, TV and the prevalence of overt hypothyroidism, subclinical hypothyroidism and goitre were significantly elevated in the thyroid antibody-positive groups in the three areas, but the FT3 was diminished (all P < 0·010). Positivity for TPOAb and TGAb was associated with an increased risk of subclinical hypothyroidism in the three areas. In areas with different median water iodine, positivity for both TPOAb and TGAb was associated with elevated TSH values. Notably, with the increased levels of TPOAb, the frequency of abnormally elevated TSH increased dramatically in the three areas.

Effect of different iodine levels on the DNA methylation of PRKAA2, ITGA6, THEM4 and PRL genes in PI3K-AKT signaling pathway and population-based validation from autoimmune thyroiditis patients.

PURPOSE: Autoimmune thyroiditis (AIT) is one of the most common autoimmune endocrine diseases. The currently recognized causes are genetic susceptibility, environmental factors and immune disorders. It is important to clarify the pathogenesis for the prevention, diagnosis, treatment of AIT and scientific iodine supplementation. This study analyzed the DNA methylation levels of PRKAA2, ITGA6, PRL and THEM4 genes related to PI3K-AKT signaling pathway, compared the DNA methylation levels between cases and controls from different water iodine levels in Shandong Province of China, and evaluated the contribution of PI3K-AKT signaling pathway-related genes in AIT. METHODS: A total of 176 adult AIT patients were included from three different water iodine areas, and 176 healthy controls were included according to gender, age and BMI. According to the results of the Illumina Methylation 850 K BeadChip in our previous research, the significant methylation differences of genes on the PI3K-AKT signaling pathway related to AIT were determined. The MethylTarget™ assay was used to detect the methylation levels of the target genes, and real-time PCR experiments were used to verify the mRNA expression levels. RESULTS: Compared with the control group, PRKAA2_3 and 15 CpG sites were hyper-methylated. ITGA6 gene and 2 CpG sites were hypo-methylated in AIT cases. The mRNA expression of ITGA6 gene was negatively correlated with the DNA methylation levels of ITGA6 gene and 2 CpG sites. Compared with cases and controls in areas with different water iodine levels, methylation differences were mainly in PRKAA2 and ITGA6 genes. The methylation levels of PRKAA2_1 and PRKAA2_3 were positively correlated with age. The methylation levels of PRL and THEM4 genes were negatively correlated with age. The methylation level of PRKAA2_3 was positively correlated with FT4. CONCLUSION: In summary, we identified aberrant DNA methylation levels of PRKAA2 and ITGA6 genes related to PI3K-AKT signaling pathway in the blood of AIT patients. Both iodine supplementation after long-term iodine deficiency and iodine excess can affect the DNA methylation levels of PRKAA2 and ITGA6 genes, and the former affects more obviously. In ITGA6 gene, this aberrant epigenetic modification is associated with the increased mRNA expression.

The Whole Blood DNA Methylation Patterns of Extrinsic Apoptotic Signaling Pathway Related Genes in Autoimmune Thyroiditis among Areas with Different Iodine Levels.

Autoimmune thyroiditis (AIT) has a complex etiology and the susceptibility to it is determined by a combination of genetic and environmental factors, although these are not yet fully understood. The present research aimed to explore the DNA methylation patterns in whole blood of extrinsic apoptotic signaling pathway related genes in AIT among areas with different iodine levels. We selected the iodine-fortification areas (IFA), iodine-adequate areas (IAA) and water-based iodine-excess areas (IEA) from Shandong Province of China as survey sites. Totally 176 AIT cases and 176 controls were included. MethylTargetTM and QT-PCR technology were used to detect candidate genes' DNA methylation levels and mRNA expression levels, respectively. We found that DAPK1 DNA methylation levels in AIT cases (especially in female) were significantly higher than controls (t=2.7715, P=0.0059; t=2.4638, P=0.0143 in female). There were differences in DAPK1(t=2.5384, P=0.0121), TNFSF8(t=2.1667, P=0.0334) and TNFAIP8(t=2.5672, P=0.0121) genes methylation between cases and controls with different water iodine levels. The mRNA expression of DAPK1(t=4.329, P<0.001) and TNFAIP8(t=3.775, P<0.001) in the cases were increased. We identified the differences in the DNA methylation status of the extrinsic apoptotic signaling pathway related genes between AIT and controls and in different iodine levels areas. The results were verified at the mRNA level. The environmental iodine may affect DNA methylation to some extent.

The Relationship between PTPN22 R620W Polymorphisms and the Susceptibility to Autoimmune Thyroid Diseases: An Updated Meta-analysis.

The protein tyrosine phosphatase non-receptor 22 (PTPN22) R620W polymorphism has been related to susceptibility to autoimmune thyroid disease (AITD) with inconsistent results. Therefore, this meta-analysis was designed to assess a more accurate association between the PTPN22 R620W polymorphism and AITD susceptibility. A systematic search of the EMBASE, PubMed, Web of Science, CBM, CNKI, and WanFang databases was performed to determine relevant publications. Statistical analyses of the odds ratios (ORs), 95% confidence intervals (CIs), and p values were performed using STATA software. Our meta-analysis included 18 separate studies comprised of 4,726 cases and 4,220 controls. In the allele and all genetic models, PTPN22 R620W polymorphism and Graves' disease (GD) (allele model TvsC: OR = 1.573; 95% CI = 1.378-1.795; P < .001) and Hashimoto's thyroiditis (HT) (allele model TvsC: OR = 1.737; 95% CI = 1.230-2.454; P = .002) susceptibility was positively associated. A racial subgroup analysis showed that the T allele significantly increased AITD susceptibility in all genetic models involving Caucasians, but not in Asians. This meta-analysis showed that the PTPN22 R620W polymorphism is associated with the risk of GD and HT in the overall study population. In addition, the PTPN22 R620W polymorphism is associated with elevated AITD risk in Caucasians, but not in Asians.

DNA Methylation Patterns in the HLA-DPB1 and PDCD1LG2 Gene Regions in Patients with Autoimmune Thyroiditis from Different Water Iodine Areas.

Background: Epigenetic disorders play an important role in the pathogenesis of autoimmune thyroiditis (AIT). Therefore, the study of the possible role of DNA methylation in AIT is of great significance to explore the pathogenesis of AIT. Methods: From May 2019 to June 2019, whole blood samples were collected from 176 AIT patients and 176 controls from different water iodine levels in Shandong Province, China. We used the Illumina Methylation 850K BeadChip to determine significant differences in methylation status of genes and used the MethylTarget™ assay to verify the methylation level in 176 cases and 176 controls. The relative mRNA levels of genes were detected by quantitative real-time-polymerase chain reaction. Results: There were multiple differential methylation sites in the HLA-DPB1 and PDCD1LG2 genes between the case and control population with different water iodine levels. Some target regions of HLA-DPB1 and PDCD1LG2 genes were negatively correlated with relative mRNA expression in the case and control populations and with different water iodine levels. Conclusions: There is differential methylation status in genomic DNA in patients with AIT. The methylation patterns of HLA-DPB1 and PDCD1LG2 genes related to cell adhesion molecule pathway may be different based on different water iodine levels. HLA-DPB1 and PDCD1LG2 genes related to the cell adhesion molecules pathway may play a role in the development of AIT. This study is registered with Chinese Clinical Trial Registry, www.chictr.org.cn, number ChiCTR2000039105.

Associations between water iodine concentration and the prevalence of dyslipidemia in Chinese adults: A cross-sectional study.

Iodine is important in both thyroid function and lipid metabolism. Some studies have explored the effect of thyroid hormones (THs) and urinary iodine concentration (UIC) on serum lipid levels. However, the association between iodine intake and dyslipidemia has not been well established. This study aimed to investigate the relationship between water iodine concentration (WIC) and dyslipidemia, including hypercholesterolemia, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C) and high low-density lipoprotein cholesterol (LDL-C). A cross-sectional survey was conducted involving 409, 390 and 436 adults (≥18 years) from the iodine-deficient (median water iodine, MWI < 10 µg/L), iodine-adequate (MWI between 40 and 100 µg/L) and iodine-excess (MWI > 100 µg/L) areas, respectively. WIC, total cholesterol (TC), triglyceride (TRIG), HDL-C and LDL-C were measured. The prevalence of dyslipidemia were calculated based on the level of WIC using the chi-square method. To further explore whether prevalence was associated with WIC, simple linear regressions and multiple logistic regression models were used. Compared to those with WIC of 40-100 µg/L, a WIC of >100 µg/L was found to be protective associated with against the occurrence of hypertriglyceridemia [adjusted odds ratio (AOR) = 0.649, 95% confidence interval (CI): 0.455-0.924] and low HDL-C (AOR = 0.429, 95% CI: 0.264-0.697). The prevalence of hypertriglyceridemia, low HDL-C and high LDL-C as a function of WIC was found to be an inverted U-shaped association with a zenith at a WIC of 40-100 µg/L. Collectively, our research showed that serum lipid levels are related to WIC. The benefit effect association between WIC and dyslipidemia appears in cases of iodine excess (>100 µg/L).

Relationship between excess iodine, thyroid function, blood pressure, and blood glucose level in adults, pregnant women, and lactating women: A cross-sectional study.

High water iodine concentration in drinking water can lead to excessive iodine, which will affect normal thyroid function, blood glucose, and blood pressure, especially among pregnant and lactating women. The aim of the present study was to determine the relationship between iodine, thyroid function, blood pressure, and blood glucose level among adults, and pregnant and lactating women in areas that are iodine-adequate (IA) and iodine-excess (IE) with respect to iodine concentrations in drinking water. A cross-sectional survey was conducted involving 144 pregnant and 237 lactating women in Shanxi Province, and 828 adults in Shandong Province. Water iodine, urinary iodine, thyroid function, blood pressure, and blood glucose were measured. Compared with the IA area, the water iodine concentration (WIC) in the IE area was higher (adults, 325.00 µg/L vs. 71.40 µg/L; pregnant and lactating women, 464.80 µg/L vs. 57.50 µg/L). For adults, and pregnant and lactating women, in the IE area, the urinary iodine concentration (UIC), free thyroxine (FT4 [except for lactating women]), and systolic blood pressure (only adults 18-40 years of age) were significantly higher, while the blood glucose level and the prevalence of hyperglycemia (except for adults) was lower, and the free triiodothyronine (FT3), thyroid-stimulating hormone (TSH), thyroglobulin antibody (TgAb), thyroid peroxidase antibody (TPOAb), and hypertension-positive rates of the three populations were not significantly different. For adults, systolic and diastolic pressure were positively correlated with FT3 and FT4, respectively, while the blood glucose level were inversely associated with the WIC. For pregnant women, systolic pressure and the WIC, diastolic pressure and FT4, blood glucose level and FT3 were all positively correlated, while the blood glucose level was inversely associated with TSH, WIC and UIC. For lactating women, systolic pressure was positively correlated with WIC and UIC, while blood glucose level were inversely associated with WIC and UIC. Pregnant and lactating women in the IE area were at lower risk for an association with hyperglycemia. Collectively, our research showed that long-term exposure to high water iodine is a high-risk factor for abnormal blood pressure and a low-risk factor for abnormal blood glucose level, especially for special populations such as pregnant and lactating women. Moreover, enhanced monitoring of blood pressure and blood glucose level in people with abnormal thyroid function in areas with high water iodine is important.

Autoimmune thyroid diseases after 25 years of universal salt iodisation: an epidemiological study of Chinese adults in areas with different water iodine levels.

The present study aimed to evaluate the status of iodine nutrition and thyroid function in adults, to understand the distribution of thyroid disease in people with autoimmune thyroid disease (AITD) in different water iodine areas and to explore the relationship between serum iodine, urine iodine and thyroid function in people with AITD. A cross-sectional survey was conducted in areas of Shandong Province with different water iodine levels, and subsequently 1225 adults were enrolled from iodine-deficient (ID), iodine-adequate (IA) and iodine-excess (IE) areas. Urinary iodine, water iodine, salt iodine, serum iodine and thyroid function were measured. According to the urine iodine concentration, the ID and IA areas were defined as iodine sufficient and the IE area as iodine excessive. Urine iodine, serum iodine, free thyroxine (FT4) and thyroid-stimulating hormone (TSH) levels were comparatively higher in the IE area. The positive rate of thyroglobulin antibody (19·1 %) and the prevalence of AITD (21·8 %) were higher in the ID areas; the prevalence of subclinical hypothyroidism was lowest in the ID areas (7·3 %) and highest in the IE area (16·3 %). Among the AITD population, urinary iodine concentration, free triiodothyronine, FT4 and TSH had a non-linear correlation with serum iodine; abnormal TSH level, serum iodine concentration > 110 µg/l and goitre were risk factors for AITD in adults, especially females. Our data collectively suggest that universal salt iodisation has improved the iodine nutritional status of the population in ID areas in China. Non-step-by-step iodine fortification may induce the transformation of thyroid autoimmune diseases from recessive-to-dominant in susceptible people. Moreover, enhanced monitoring of thyroid function in people with AITD is important.

Association between TSHR gene methylation and papillary thyroid cancer: a meta-analysis.

PURPOSE: To explore the association between the thyroid stimulating hormone receptor (TSHR) gene methylation and human papillary thyroid cancer (PTC), as well as PTC related clinicopathological indicators. METHODS: We searched PubMed, Embase, Medline, and Web of Science databases through computer for articles published in English on association between methylation of TSHR gene and PTC. Articles published in Chinese were searched in China National Knowledge Infrastructure (CNKI), WanFang, China Biology Medicine (CBM) disc, and WeiPu databases. Database search took place in the 4th week of October. RESULTS: Totally 914 samples from 14 case-control studies were included in our meta-analysis. The methylation rate of TSHR gene in PTC group was significantly greater than that in control group (OR = 6.45, 95% CI 3.03, 13.71, P < 0.001). The subgroup analysis results showed the incidence of TSHR gene methylation was higher in autologous controls (OR = 16.39, 95% CI 8.83, 30.42, P < 0.001), Asian races (OR = 8.26, 95% CI 3.54, 19.23, P < 0.001), and Chinese (OR = 11.40, 95% CI 5.56, 23.39, P < 0.001). Hierarchical analysis of PTC related clinicopathological indicators showed that TSHR gene methylation rate are higher in PTC patients over 45 years (OR = 1.65, 95% CI 1.07, 2.55, P < 0.05) and lymph node metastasis (OR = 5.36, 95% CI 1.54, 18.67, P < 0.01). In addition, the occurrence of TSHR gene methylation had also been shown to be related to the clinical stage (OR = 0.23, 95% CI 0.07, 0.70, P < 0.05) and size (OR = 0.19, 95% CI 0.11, 0.32, P < 0.01) of tumors. The result of sensitivity analysis showed the combined results of the studies included in the meta-analysis were fairly stable. Begg's and Egger's tests also suggested that there was no significance publication bias (P > 0.1). CONCLUSIONS: The rate of TSHR gene methylation is higher in PTC and it may be associated with the pathogenesis of human PTC, suggesting that TSHR gene may be a candidate marker for PTC diagnosis. In addition, the occurrence of TSHR gene methylation in PTC patients is closely related to age, lymph node metastasis, clinical stage, and tumor size, suggesting that TSHR gene may be used as an index to judge the severity of PTC.

The Relationship between High Iodine Consumption and Levels of Autoimmune Thyroiditis-Related Biomarkers in a Chinese Population: a Meta-Analysis.

To comprehensively evaluate the relationship between high iodine concentration and biomarker abnormalities related to autoimmune thyroiditis in a Chinese population. Medline, PubMed, and Embase electronic databases were searched for articles published domestically and internationally on the relationship between high iodine concentrations and thyroid hormone antibodies and thyroid-stimulating hormone in China before March 2019. Articles published in Chinese were searched in the China Biology Medicine (CBM) disc, Wanfang Database, and China National Knowledge Infrastructure (CNKI). A total of 16 cross-sectional articles were included in this study, including 9061 participants. A meta-analysis was conducted in Stata 14.0. The binary categorical and continuous variables used odds ratios (ORs) and standardized mean differences (SMDs) with the corresponding 95% confidence intervals (CIs) as the effect statistics, respectively. The results showed that high iodine concentrations had a minimal association with the abnormal rates of thyroid peroxidase antibody (TPOAb) (OR = 1.274, 95% CI (0.957, 1.695), P > 0.05) and thyroglobulin antibody (TGAb) (OR = 1.217, 95% CI (0.911, 1.626), P > 0.05) in the entire population. The thyroid-stimulating hormone (TSH) level in the high iodine group was greater than that in the adaptive iodine group (SMD = 0.202, 95% CI (0.096, 0.309), P < 0.05). The results of the subgroup analysis showed that the abnormal TPOAb rate in pregnant women (OR = 1.519, 95% CI (1.007, 2.291), P < 0.05) and children (OR = 3.365, 95% CI (1.966, 5.672), P < 0.05) in the high iodine group was greater than that in the adaptive iodine group, and the abnormal TGAb rate of children in the high iodine group was greater than that in the adaptive iodine group. The TSH levels of lactating women (SMD = 0.24, 95% CI (0.053, 0.427), P < 0.05), pregnant women (SMD = 0.301, 95% CI (0.176, 0.426), P < 0.05), and children (SMD = 0.25, 95% CI(0.096, 0.309), P < 0.05) in the high iodine group were higher than those in the adaptive iodine group. Egger's and Begg's tests showed no significant (P > 0.1) publication bias. High iodine can increase the risk of abnormal levels of TPOAb, TGAb, and TSH related to autoimmune thyroiditis in pregnant women, lactating women, and children in China.