Thyroid hormone and obesity

Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) Combined With Obesity Leads to Elevated Thyroid Hormone Levels

Introduction: Research indicates a strong link between obesity and alterations in thyroid function among patients diagnosed with obstructive sleep apnea-hypopnea syndrome (OSAHS). Our study aims to investigate the thyroid hormone levels in patients with OSAHS combined with obesity. It seeks to elucidate the changes in thyroid hormones and their potential metabolic risks in these patients, thereby further clarifying the role and clinical significance of thyroid function alterations in OSAHS complicated by obesity. Methods: One hundred and thirty-four patients were divided into four groups, including the normal group, the obesity group, the OSAHS with the obesity group, and the OSAHS group. Serum levels of free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were analyzed using electrochemiluminescence immunoassay. Clinical metabolic parameters (total cholesterol [TC], triglycerides [TG], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C]) and sleep respiratory monitoring indicators (apnea-hypopnea index [AHI], longest duration of sleep apnea [TAmax], oxygen desaturation index [ODI], mean oxygen saturation [M-SaO2], and lowest oxygen saturation [L-SaO2]) were also recorded. Results: The OSAHS with the obesity group demonstrated elevated FT3, TSH, and ODI levels but lower L-SaO2 level than other groups, and the levels of TG and LDL-C were higher than those in the OSAHS group and the normal group. Additionally, TSH level was positively correlated with LDL-C and BMI, but negatively correlated with L-SaO2. In the obesity group, FT3, TSH, TG, ODI, and TAmax levels were higher, while L-SaO2 and M-SaO2 were lower than those in the normal group. Conclusions: Patients with both OSAHS and obesity are at higher risk of developing subclinical hypothyroidism, with LDL-C, BMI, and L-SaO2 levels likely contributing to changes in TSH levels.

Exploring the Link Between Thyroid Disorders and Obesity: Mechanisms, Impacts, and Clinical Implications

OBJECTIVE

Obesity and thyroid dysfunction are among the most significant challenges in endocrinology, frequently overlapping to create complexities in weight management. Even after achieving euthyroidism, weight variations persist, significantly affecting patients' quality of life. This review explores the mechanisms linking hypothyroidism and hyperthyroidism to weight fluctuations, emphasizing their impact on basal metabolic rate, appetite regulation, glucose and lipid metabolism, and thermogenesis.

METHODS

We conducted a comprehensive review using PubMed and Google Scholar, applying the search criteria: (obesity OR overweight) AND (Hashimoto's thyroiditis OR hyperthyroidism OR hypothyroidism OR Thyroid Cancer). From this search, we reviewed 500 publications and finally included 71 publications, focusing on broad clinical questions regarding the role of thyroid hormones in weight regulation and metabolism, the impact of thyroid disorders and their treatments on obesity, and approaches for managing obesity in the context of thyroid dysfunction.

RESULTS

In hypothyroidism, the impact of levothyroxine therapy on weight changes is discussed, along with the potential role of T3 supplementation. For hyperthyroid patients, the effects of antithyroid medications, radioactive iodine therapy, and thyroidectomy on weight regulation are explored. Pharmacological and nonpharmacological strategies for managing obesity in thyroid disorders are reviewed. Lifestyle interventions and pharmacotherapies are evaluated for their efficacy and potential effects on thyroid function. Lastly, the implications of bariatric surgery are explored, including its effects on thyroid function, medication absorption, and postsurgical management of thyroid disorders.

CONCLUSION

This review underscores the importance of an integrated, multidisciplinary approach to managing obesity in the context of thyroid dysfunction to optimize patient outcomes.

Free triiodothyronine and triglyceride-glucose index interaction on metabolic dysfunction-associated steatotic liver disease risk in euthyroid individuals

Background

The link between thyroid function and insulin resistance and metabolic dysfunction-associated fatty liver disease (MASLD) is becoming increasingly recognized. The primary goal of this study was to investigate the relationship between free triiodothyronine (FT3) levels, the triglyceride-glucose index (TyG) index, and the likelihood of MASLD in euthyroid individuals.

Methods

A cross-sectional analysis of 18,298 euthyroid individuals was conducted, comparing 6,144 with MASLD to 12,154 controls. The study evaluated indicators related to clinical, metabolic, and thyroid function. The combined effect of the FT3 and TyG index on the likelihood of MASLD was assessed using logistic regression.

Results

The MASLD group presented with higher male prevalence, older age, and increased rates of hypertension and diabetes. Significant correlations were observed between FT3, TyG, and metabolic parameters. After controlling for potential confounders, FT3 remained significantly associated with increased MASLD risk (adjusted OR = 1.35, 95% CI: 1.23-1.49; P < 0.001). Similarly, the TyG index was independently associated with higher MASLD risk (adjusted OR = 3.99, 95% CI: 3.40-4.68; P < 0.001). The high FT3 (≥ 4.98 pmol/L)/high TyG (≥ 8.55) group exhibited significantly elevated MASLD risk compared to the low FT3/low TyG group (OR = 5.38, 95% CI: 4.62-6.26; P < 0.001).

Conclusion

Elevated FT3 and TyG index are independently associated with an increased risk of MASLD, and they exhibit a significant synergistic additive interaction.

Resting metabolic rate in obesity

The prevalence of obesity has continued to rise, and obesity and its attendant metabolic disorders are major global health threat factors. Among the current interventions for obesity, none have demonstrated sustained efficacy in achieving long-term outcomes. So, the identification of therapeutic targets is of paramount importance in the advancement and sustainability of obesity. Resting metabolic rate (RMR) constitutes 60%-75% of total energy expenditure and serves a crucial function in maintaining energy balance. Nevertheless, there exists considerable heterogeneity in RMR among individuals. Low RMR is associated with weight gain, elevating the susceptibility to obesity-related ailments. Hence, RMR will be the main focus of interest in the study of obesity treatment. In this review, we will elucidate the influence factors and mechanisms of action of RMR in obesity, with particular emphasis on the effects of obesity treatment on RMR and the alterations and influence factors of RMR in special types of populations with obesity.

Prevalence and Risk Factors of Subclinical Hypothyroidism in Young and Middle-Aged Patients With First-Episode Drug-Naïve Major Depressive Disorder

Background: Subclinical hypothyroidism (SCH) is a mild impairment of thyroid function. The prevalence of SCH is significantly higher in the major depressive disorder (MDD) population than in the general population, but the risk factors and relationships are not apparent. The occurrence of SCH is influenced by age and medication. Therefore, our study was to investigate the prevalence and risk factors of SCH in young and middle-aged groupstotal of patients with first-episode and drug-naive (FEDN) MDD. Methods: A total of 1717 FEDN MDD patients were divided into a younger group (18-45 years) and a middle-aged group (>45 years). The Hamilton Depression Scale (HAMD) was used to assess patients' depression symptoms. Serum thyroid function and lipid level parameters were measured. A self-administered questionnaire collected other clinical and demographic data. Results: The prevalence of SCH in middle-aged MDD patients was 66.9%. Middle-aged patients had a longer duration of illness, a later age of onset, a higher proportion of female patients, and a lower level of education. Further logistic regression indicated that serum total cholestrol (TC) and high-density lipoprotein cholesterol (HDL-C) levels, as well as overweight and obesity, were significantly associated with SCH in both groups; however, low-density lipoprotein cholesterol (LDL-C) was an independent risk factor associated with SCH in the middle-aged group. Conclusions: Our results suggest that the prevalence of SCH is higher in middle-aged MDD patients than in younger patients and that long-term more severe depression, high TC and HDL-C levels, and abnormal body weight may influence the occurrence of SCH. Physicians should pay more attention to LDL-C levels in middle-aged patients with FEDN MDD.

Comparative Hypothalamic Proteomic Analysis Between Diet-Induced Obesity and Diet-Resistant Rats

Obesity arises from a complex interplay of genetic and environmental factors. Even among individuals with the same genetic predisposition, diet-induced obesity (DIO) exhibits varying degrees of susceptibility, which are categorized as DIO and diet-induced obesity resistance (DR). The hypothalamus plays a pivotal role in regulating energy homeostasis. This study performed a comparative hypothalamic proteomic analysis in DIO and DR rats to identify differentially expressed proteins (DEPs) associated with alterations in body weight. Male Sprague Dawley rats were fed either a standard chow diet or a high-fat diet for 12 weeks. DIO rats exhibited the most rapid weight gain compared to both the control and DR rats. Despite consuming similar caloric intake, DR rats exhibited less weight gain relative to DIO rats. Proteomic analysis revealed 31 DEPs in the hypothalamus of DR rats compared to DIO rats (with a false discovery rate (FDR) < 1%). Notably, 14 proteins were upregulated and 17 proteins were downregulated in DR rats. Gene ontology analysis revealed an enrichment of ion-binding proteins, such as those binding to Fe2+, Zn2+, Ca2+, and Se, as well as proteins involved in neuronal activity and function, potentially enhancing neuronal development and cognition in DR rats. The DEPs pathway analysis via the Kyoto Encyclopedia of Genes and Genomes (KEGG) implicated starch and sucrose metabolism, antigen processing and presentation, and the regulation of inflammatory mediator affecting TRP channels. Western blotting confirmed the proteomic findings for TRPV4, CaMKV, RSBN1, and BASP1, which were consistent with those obtained from Tandem Mass tag (TMT) proteomic analysis. In conclusion, our study highlights the hypothalamic proteome as a critical determinant in the susceptibility to DIO and provides novel targets for obesity prevention and treatment.

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.

Roles of thyroid and leptin hormones and their crosstalk in male reproductive functions: an updated review

PURPOSE

This review aims to provide updated information regarding the role of thyroid and leptin hormones and their crosstalk in affecting the male reproductive function in hypothyroid and obesity conditions.

METHOD

A wide literature search was made using online search engines on published articles using keywords including thyroid hormone, hypothyroidism, leptin hormone, hyperleptinemia, obesity, the relationship between thyroid and leptin hormones and male reproduction, and hypothyroidism, obesity, and male reproduction.

RESULTS

All information pertaining thyroid and leptin hormone effects on male reproduction, hypothyroidism, hyperleptinemia, and obesity effect on male fertility as well as the related molecular mechanisms are obtained.

CONCLUSION

Thyroid and leptin hormones individually play a significant role in male reproduction. Alterations of these hormones' levels could adversely affect the male reproductive functions. PI3K/AKT signaling was found to be the major signaling pathway involved in mediating the effect of both hormones on male reproduction. Impaired crosstalk between the two hormones may occur in hypothyroidism with obesity which would contribute towards male reproductive dysfunction.

Unlocking Fertility: How Nitric Oxide Pathways Connect Obesity and Reproductive Health-The Role of Bariatric Surgery

This study examines the relationship between obesity, oxidative stress, and reproductive dysfunction. It focuses on the effects of sleeve gastrectomy on gene expression and hormone profiles in 29 women with severe obesity (BMI ≥ 40 kg/m2). Pre- and post-surgical investigations revealed significant differences in major gene expressions and hormonal markers. CART expression reduced significantly from 0.27 ± 4.43 to -3.42 ± 1.14 (p < 0.001), while leptin expression decreased from -1.87 ± 1.75 to -0.13 ± 1.55 (p < 0.001), indicating better metabolic regulation. In contrast, eNOS expression increased considerably from -4.87 ± 1.70 to 1.18 ± 2.31 (p = 0.003), indicating improved endothelial function and nitric oxide bioavailability, which is critical for vascular health and reproduction. Correlation research before surgery indicated no significant relationships between eNOS, CART, or leptin and clinical indicators, implying that these genes function independently in pre-surgical metabolism. While most associations remained negligible after surgery, a significant negative connection between eNOS expression and SHBG levels appeared (r = -0.365, p = 0.049), indicating potential interactions in hormonal regulation pathways following metabolic improvements. These findings emphasize the importance of bariatric surgery in reducing the negative effects of obesity on reproductive health by altering critical cellular pathways. Significant increases in CART, leptin, and eNOS expression indicate reduced oxidative stress, improved vascular tone, and hormonal balance, all of which contribute to increased reproductive capacity. This study sheds light on the molecular processes that link obesity, metabolic health, and fertility, underlining bariatric surgery's therapeutic potential for women experiencing obesity-related infertility.

Thyroid Function and Anthropometric Measures: A Systematic Review and Meta-Analysis

OBJECTIVE

Although often enquired about by patients, the association of thyroid function with anthropometric measures in the general population is unclear. We summarized population-based studies and randomized controlled trials (RCTs) on the association between thyroid function and anthropometric measures.

METHODS

We systematically searched Embase, Medline (Ovid), and Cochrane Central Register of Controlled Trials from inception until June 28, 2023. We included studies in adults examining thyroid function or thyroid disease as exposure and anthropometric measures as outcome (eg, body mass index [BMI], weight). We used random effect meta-analyses to pool the results.

RESULTS

We included 64 studies in the qualitative synthesis, and 21 in the quantitative synthesis (total participants n = 107 734 for cross-sectional studies, n = 22 010 for longitudinal studies, n = 80 for RCTs). The evidence was limited and heterogeneous, particularly for longitudinal studies. Cross-sectionally, we described an association for thyroid-stimulating hormone (TSH) concentrations and BMI (B per 1 mIU/L increase of TSH = 0.21; 95% confidence interval [CI], 0.09-0.32) and for free thyroxine (FT4) and BMI (B = -0.14; 95% CI, -0.23 to -0.05). Longitudinally, increasing TSH concentrations were related to weight gain and increasing FT4 concentrations to weight loss.

CONCLUSION

We showed a relation between higher TSH concentrations and higher BMI or weight, and between higher FT4 concentrations and lower BMI or weight, although effect sizes were modest. We highlight the need of more high-quality longitudinal studies. Despite the relevance of the association between thyroid (dys-)function and anthropometric measures, evidence is scarce.

Treatment of Obesity with Thyroid hormones in Europe. Data from the THESIS* Collaboration

PURPOSE

The use of thyroid hormones (TH) to treat obesity is unsupported by evidence as reflected in international guidelines. We explored views about this practice, and associations with respondent characteristics among European thyroid specialists.

METHODS

Specialists from 28 countries were invited to a survey via professional organisations. The relevant question was whether "Thyroid hormones may be indicated in biochemically euthyroid patients with obesity resistant to lifestyle interventions".

RESULTS

Of 17,232 invitations 5695 responses were received (33% valid response rate; 65% women; 90% endocrinologists). Of these, 290 (5.1%) stated that TH may be indicated as treatment for obesity in euthyroid patients. This view was commoner among non-endocrinologists (8.7% vs. 4.7%, p < 0.01), private practice (6.5% vs. 4.5%, p < 0.01), and varied geographically (Eastern Europe, 7.3%; Southern Europe, 4.8%; Western Europe, 2.7%; and Northern Europe, 2.5%). Respondents from Northern and Western Europe were less likely to use TH than those from Eastern Europe (p < 0.01). Gross national income (GNI) correlated inversely with this view (OR 0.97, CI: 0.96-0.97; p < 0.001). Having national guidelines on hypothyroidism correlated negatively with treating obesity with TH (OR 0.71, CI: 0.55-0.91).

CONCLUSIONS

Despite the lack of evidence, and contrary to guidelines' recommendations, about 5% of respondents stated that TH may be indicated as a treatment for obesity in euthyroid patients resistant to life-style interventions. This opinion was associated with (i) respondent characteristics: being non-endocrinologist, working in private practice, treating a small number of hypothyroid patients annually and (ii) national characteristics: prevalence of obesity, Eastern Europe, low GNI and lack of national hypothyroidism guidelines.

Obstructive Sleep Apnea‐Hypopnea Syndrome (OSAHS) Combined With Obesity Leads to Elevated Thyroid Hormone Levels

Introduction: Research indicates a strong link between obesity and alterations in thyroid function among patients diagnosed with obstructive sleep apnea‐hypopnea syndrome (OSAHS). Our study aims to investigate the thyroid hormone levels in patients with OSAHS combined with obesity. It seeks to elucidate the changes in thyroid hormones and their potential metabolic risks in these patients, thereby further clarifying the role and clinical significance of thyroid function alterations in OSAHS complicated by obesity.

Methods: One hundred and thirty‐four patients were divided into four groups, including the normal group, the obesity group, the OSAHS with the obesity group, and the OSAHS group. Serum levels of free triiodothyronine (FT3), free thyroxine (FT4), and thyroid‐stimulating hormone (TSH) were analyzed using electrochemiluminescence immunoassay. Clinical metabolic parameters (total cholesterol [TC], triglycerides [TG], high‐density lipoprotein cholesterol [HDL‐C], low‐density lipoprotein cholesterol [LDL‐C]) and sleep respiratory monitoring indicators (apnea‐hypopnea index [AHI], longest duration of sleep apnea [TAmax], oxygen desaturation index [ODI], mean oxygen saturation [M‐SaO2], and lowest oxygen saturation [L‐SaO2]) were also recorded.

Results: The OSAHS with the obesity group demonstrated elevated FT3, TSH, and ODI levels but lower L‐SaO2 level than other groups, and the levels of TG and LDL‐C were higher than those in the OSAHS group and the normal group. Additionally, TSH level was positively correlated with LDL‐C and BMI, but negatively correlated with L‐SaO2. In the obesity group, FT3, TSH, TG, ODI, and TAmax levels were higher, while L‐SaO2 and M‐SaO2 were lower than those in the normal group.

Conclusions: Patients with both OSAHS and obesity are at higher risk of developing subclinical hypothyroidism, with LDL‐C, BMI, and L‐SaO2 levels likely contributing to changes in TSH levels.

Autoimmune Thyroid Disease in Patients with Down Syndrome-Review

Down syndrome develops due to the presence of supernumerary chromosome 21. This diagnosis is made in approximately 1:800 live births. The tendency to develop autoimmune disorders like idiopathic arthritis, celiac disease, diabetes mellitus type 1, vitiligo and autoimmune thyroid disease is strongly expressed in patients with Down syndrome. Autoimmune thyroid diseases consisting of Hashimoto's thyroiditis and Graves' disease are specifically prevalent in patients with Down syndrome. The aim of our study is to collect available data connecting the pathogenesis and clinical course of autoimmune thyroid diseases in patients with Down syndrome of different ages and compare them to control groups. According to published data, the incidence ratio of Hashimoto's thyroiditis diagnosis in patients with Down syndrome is elevated compared to in age-matched controls without this chromosomal aberration, similarly to Graves' disease risk, which is also increased in a group of patients with Down syndrome. What is more, both Hashimoto's thyroiditis and Graves' disease are diagnosed at an earlier age than in the healthy population and are not correlated with gender or a family history of autoimmune diseases.

Association of Dietary Inflammatory Index and Thyroid Function in Patients with Hashimoto's Thyroiditis: An Observational Cross-Sectional Multicenter Study

Background and Objectives: The available research suggests that dietary patterns with high inflammatory potential, as indicated by a high DII score, may exacerbate inflammation and potentially influence thyroid function. Therefore, the aim of this study was to investigate the associations between the inflammatory potential of a diet and thyroid function in adults with Hashimoto's thyroiditis (HT). Materials and Methods: A total of 149 adults diagnosed with Hashimoto's thyroiditis were enrolled in this observational, cross-sectional, multicenter study. The Dietary Inflammatory Index (DII®) was calculated using a 141-item food frequency questionnaire (FFQ). The serum levels of the thyroid-stimulating hormone (TSH), free thyroxine (fT4), thyroid peroxidase antibodies (TPO-Ab), and high-sensitivity C-reactive protein (hsCRP) were determined. Results: The DII® scores ranged from -3.49 (most anti-inflammatory) to +4.68 (most pro-inflammatory), whereas three DII® tertile ranges were defined as <-1.4, -1.39 to +1.20, and >+1.21, respectively. Participants in tertile 1 (more anti-inflammatory diet) had significantly higher levels of fT4 than those adhering to a more pro-inflammatory diet (p = 0.007). The levels of hsCRP and TSH appeared to increase with increasing the DII® score, but without statistical significance. A significant association was found between the DII® and TSH (β = 0.42, p < 0.001) and between DII® and free thyroxine (β = 0.19, p < 0.001). After adjustment for age, gender, energy intake, and physical activity, a significant positive correlation remained between the DII® and TSH (β = 0.33, p = 0.002) and between the DII® and body mass index (BMI) (β = 0.14, p = 0.04). Conclusions: Adherence to an anti-inflammatory diet appears to be beneficial in patients with Hashimoto's thyroiditis, suggesting that dietary modification aimed at lowering DII® levels may be a valuable strategy to improve clinical outcomes in these patients.

Triiodothyronine (T3) promotes browning of white adipose through inhibition of the PI3K/AKT signalling pathway

Obesity arises from an imbalance between energy consumption and energy expenditure, and thyroid hormone levels serve as a determinant of energy expenditure. We conducted experiments at the animal and cellular levels and combined those findings with clinical data to elucidate the role of triiodothyronine (T3) in facilitating the browning of white adipose tissue (WAT) and its underlying mechanism. The results showed (i) the impaired metabolic function of local WAT and the compensatory elevation of systemic thermogenesis in obesity; (ii) T3 treatment of white adipocytes in vitro and local WAT in vivo induced a shift towards a morphologically "brown" phenotype, accompanied by upregulation of mRNA and protein expression of browning-related and mitochondrial function markers, which suggest that T3 intervention promotes the browning of WAT; and (iii) the aforementioned processes could be modulated through inhibition of the PI3K/AKT signalling pathway; however, whether T3 affects the PI3K/AKT signalling pathway by affecting insulin signalling remains to be studied and clarified. The results of our study indicate that T3 treatment promotes browning of WAT through inhibition of the PI3K/AKT signalling pathway; these findings offer novel perspectives regarding the potential of localised therapies for addressing WAT volume in individuals with obesity.

Gestational bisphenol A exposure alters energy homeostasis and adult hypothalamic neurogenesis in female mice

Regulation of physiological homeostasis, including energy balance, is thought to be modified by low levels of adult neurogenesis in the hypothalamus. Hormones such as oestradiol can influence both embryonic and adult hypothalamic neurogenic programs, demonstrating a sensitivity of hypothalamic neural progenitor cells to endogenous hormones. Previously we showed that gestational exposure to environmental levels of the xenoestrogen bisphenol A (BPA) changed neural progenitor cell behaviors in the embryo; however, we did not examine if these changes were permanent to affect adult neurogenesis. Here we investigated whether adult neuro- and/or gliogenesis were altered in mice prenatally exposed to BPA and placed on a high-fat diet challenge. Gestationally exposed adult female mice on a standard diet gained less weight than non-BPA controls, whereas gestationally exposed BPA females on a high-fat diet gained more weight than controls. Males exposed to gestational BPA showed no differences in weight gain relative to control males. Concomitantly, adult neurogenesis was increased in the VMH, DMH, and PVN of adult female mice exposed to BPA on standard diet, suggesting that disrupted adult neurogenesis might perturb normal energy balance regulation in females. These results add to growing evidence that low-dose BPA exposure in utero causes changes to adult hypothalamic function.

Secular Increasing Trends in Female Thyroid Cancer Incidence in Taiwan

BACKGROUND

Thyroid cancer incidence has increased globally in recent decades, especially in females, although its trends in Taiwan have not been studied extensively. This study aimed to investigate changes in female incidence and possible causes of thyroid cancer in Taiwan.

METHODS

Using the Taiwan Cancer Registry (TCR) Database, age-standardized incidence rates, age-specific incidence rates and birth cohorts were calculated. Correlation between female thyroid cancer incidence and cohort fertility rates were examined.

RESULTS

Thyroid cancer incidence increased in Taiwanese female, with age-adjusted rates per 100,000 people increasing from 7.37 during 1995-1999 to 20.53 during 2015-2019; the annual percentage change (APC) was 5.9% (95% CI, 5.3-6.5). Age-specific incidence rates increased with age, with peak rates occurring at younger ages. The APCs in the 50-54 age group were the highest (6.8%, 95% CI, 6.1-7.5). Incidence rates also increased with later birth cohorts. We observed a significant negative correlation between thyroid cancer incidence and fertility rates in the same birth cohort.

CONCLUSIONS

We hypothesize that overdiagnosis may be a main reason for the rapidly increasing thyroid cancer incidence in Taiwanese females. Notably, we observed a strong negative correlation between fertility and thyroid cancer incidence. However, our study is limited by the absence of individual-level cancer data in the TCR database. These associations with fertility will be an important subject for future thyroid cancer research.

Effects of N-acetylcysteine on the expressions of UCP1 and factors related to thyroid function in visceral adipose tissue of obese adults: a randomized, double-blind clinical trial

BACKGROUND

Evidences have shown that obesity is influenced by various factors, including various hormones such as thyroid hormones and the body's metabolism rate. It seems that practical solutions such as weight loss diets and common drugs can affect these potential disorders. In this study, we investigate one of these common drugs, N-Acetylcysteine (NAC), on expressions of UCP1 and factors related to thyroid function in adults with obesity.

METHODS AND ANALYSIS

The current investigation was carried out as a randomized clinical trial (RCT) including 43 adults with obesity who were potential candidates for bariatric surgery. These individuals were randomly divided into two groups: 600 mg of NAC (n = 22) or placebo (n = 21) for a duration of 8 weeks. Visceral adipose tissue was utilized in the context of bariatric surgery to investigate the gene expression of UCP1 and thyroid function. Polymerase chain reaction (PCR) was performed in duplicate for UCP1, DIO2, DIO3, THRα and β, and 18s RNA (as an internal control) using the provided instructions to investigate the expression of the respective genes.

RESULTS

Our findings revealed that after 8 weeks compared to placebo, NAC caused a significant decrease in the expression of the DIO3 gene as one of the genes related to thyroid function and metabolism. However, regarding other related genes, no statistically significant was found (despite the increase in UCP1, DIO2, and THRα expression and decrease in THRβ expression). In addition, after adjustment of possible confounders, no significant effect was observed on anthropometric factors and serum levels of thyroid hormones.

CONCLUSION

The results of this study indicate that, following an 8-week period, NAC effectively decreases the expression of the DIO3 gene in the visceral fat tissue, in comparison to the placebo.

Risk Factors for Thyroid Dysfunction in Pregnancy: An Individual Participant Data Meta-Analysis

Background: International guidelines recommend targeted screening to identify gestational thyroid dysfunction. However, currently used risk factors have questionable discriminative ability. We quantified the risk for thyroid function test abnormalities for a subset of risk factors currently used in international guidelines. Methods: We included prospective cohort studies with data on gestational maternal thyroid function and potential risk factors (maternal age, body mass index [BMI], parity, smoking status, pregnancy through in vitro fertilization, twin pregnancy, gestational age, maternal education, and thyroid peroxidase antibody [TPOAb] or thyroglobulin antibody [TgAb] positivity). Exclusion criteria were pre-existing thyroid disease and use of thyroid interfering medication. We analyzed individual participant data using mixed-effects regression models. Primary outcomes were overt and subclinical hypothyroidism and a treatment indication (defined as overt hypothyroidism, subclinical hypothyroidism with thyrotropin >10 mU/L, or subclinical hypothyroidism with TPOAb positivity). Results: The study population comprised 65,559 participants in 25 cohorts. The screening rate in cohorts using risk factors currently recommended (age >30 years, parity ≥2, BMI ≥40) was 58%, with a detection rate for overt and subclinical hypothyroidism of 59%. The absolute risk for overt or subclinical hypothyroidism varied <2% over the full range of age and BMI and for any parity. Receiver operating characteristic curves, fitted using maternal age, BMI, smoking status, parity, and gestational age at blood sampling as explanatory variables, yielded areas under the curve ranging from 0.58 to 0.63 for the primary outcomes. TPOAbs/TgAbs positivity was associated with overt hypothyroidism (approximate risk for antibody negativity 0.1%, isolated TgAb positivity 2.4%, isolated TPOAb positivity 3.8%, combined antibody positivity 7.0%; p < 0.001), subclinical hypothyroidism (risk for antibody negativity 2.2%, isolated TgAb positivity 8.1%, isolated TPOAb positivity 14.2%, combined antibody positivity 20.0%; p < 0.001) and a treatment indication (risk for antibody negativity 0.2%, isolated TgAb positivity 2.2%, isolated TPOAb positivity 3.0%, and combined antibody positivity 5.1%; p < 0.001). Twin pregnancy was associated with a higher risk of overt hyperthyroidism (5.6% vs. 0.7%; p < 0.001). Conclusions: The risk factors assessed in this study had poor predictive ability for detecting thyroid function test abnormalities, questioning their clinical usability for targeted screening. As expected, TPOAb positivity (used as a benchmark) was a relevant risk factor for (subclinical) hypothyroidism. These results provide insights into different risk factors for gestational thyroid dysfunction.

l-Theanine Prevents Colonic Damage via NF-κB/MAPK Signaling Pathways Induced by a High-Fat Diet in Rats

SCOPE

l-Theanine (l-Thea) is an amino acid which is naturally present in tea leaves. It has been associated with possible health advantages, including obesity prevention, but the underlying molecular mechanisms have not been elucidated.

METHODS AND RESULTS

A multiomics approach is utilized to examine the mechanism by which l-Thea exerts its antiobesity effects. This study reveals that l-Thea administration significantly ameliorates high-fat diet (HFD)-induced obesity in rats by improving body weight and hyperlipidemia. l-Thea mitigates HFD-induced inflammation and reverses hepatic and colonic damage, and intestinal barrier. This research verifies that the preventive effect of l-Thea on obesity in rats induced by an HFD with colitis is accomplished by suppressing the phosphorylation of important proteins in the NF-κB/mitogen-activated protein kinase (MAPK) pathways. Metabolome analysis reveals that l-Thea regulates HFD-induced metabolic disorders, specifically through modulation of steroid hormone biosynthesis. Microbiome analysis reveals that l-Thea mitigates HFD-induced dysbiosis by increasing the relative abundance of obesity-associated probiotic bacteria, including Blautia coccoides and Lactobacillus murinus, while simultaneously suppressing the abundance of pathogenic bacteria.

CONCLUSIONS

l-Thea alleviates colitis generated by an HFD by restoring the integrity of the intestinal barrier, suppressing inflammation through regulation of MAPK/NF-κB signaling pathways, and enhancing microbial metabolism in colon.

Thyroid hormone levels and BMI-SDS changes in adolescents with obesity

Background

Thyroid hormones play an important role in energy metabolism and weight control, explained mostly by inducing thermogenesis and increasing basal metabolic rate. It has recently been shown that FT4 levels are associated with food preferences, which might also play a role in modulating body weight. The aim of this longitudinal follow-up study was to analyze the relationship of thyroid hormones levels (FT4, TSH) at baseline with weight/BMI-SDS changes in children and adolescents with obesity.

Methods

Three hundred seventy-seven children and adolescents have been enrolled to this study and followed up without a systematic intervention program for 5.59 ± 1.85months. Children and adolescents were divided into three subgroups: 1) 144 adolescents with obesity (15-19 years), 2) 213 children with obesity (10-14.9 years), and 3) 20 lean adolescents (15-19 years). Thyroid hormones were measured at the baseline, and anthropometry was performed at the baseline and during the follow-up. For further analyses, participants were divided according to the BMI-SDS change into two groups: 1. with BMI-SDS decrease, and 2. with BMI-SDS increase.

Results

Adolescents with obesity from the BMI-SDS decrease group had significantly lower baseline serum levels of TSH compared to the BMI-SDS increase group (2.4 ± 1.0 vs. 3.2 ± 2.0mIU/l; p=0.005). Similar difference was found for FT4 levels (14.7 ± 2.2 in the BMI-SDS decrease group vs. 15.5 ± 2.7pmol/l in the BMI-SDS increase group, p=0.048). Moreover, the BMI-SDS decrease was present in significantly higher percentage of adolescents with obesity with lower than median TSH level compared to those with higher than median TSH level at baseline (61.1% vs 38.6%, p=0.011). Likewise, the BMI-SDS decrease was present in significantly higher percentage of adolescent females with obesity and lower than median FT4 compared to those with higher than median FT4 level at baseline (70.6% vs. 23.5%, p<0.001). No associations of baseline thyroid hormones with the BMI-SDS change were observed in children with obesity or lean adolescents.

Conclusion

Adolescents with obesity and increased BMI-SDS during the follow-up had significantly higher baseline levels of both TSH and FT4 compared to BMI-SDS decrease group. These results support the previous findings that higher FT4 in individuals with obesity may influence weight gain.

Association between the Systemic Immune-Inflammation Index and Thyroid Function in U.S. Adults

Background

The systemic immune-inflammation index (SII) is used as an indicator of prognosis for a wide range of diseases. Thyroid function has been found to be strongly associated with inflammation. The purpose of this investigation was to analyze the correlation between SII and various thyroid functions.

Methods

This study utilized data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012. The association between SII and thyroid function was analyzed using weighted univariate and multivariate linear regression analyses. Subgroup analyses, interaction tests, and weighted restricted cubic spline (RCS) regression analyses were also employed to test this correlation.

Results

Of the 6,875 participants (age ≥ 20 years), the mean age was 46.87 ± 0.40 years. The adjusted model showed that lnSII was negatively correlated with FT3 (β = -0.0559, 95% CI -0.1060 to -0.0059,) and FT3/FT4 (β = -0.0920, 95% CI -0.1667 to -0.0173,). There was a positive correlation between lnSII and TT4 (β = 0.1499, 95% CI 0.0722-0.2276,). In subgroup analyses, lnSII still independently affected a wide range of thyroid functions. Weighted RCS analysis showed a nonlinear relationship between FT3 and lnSII.

Conclusion

Close relationships exist between SII and a variety of thyroid functions. SII can be used as an indicator to predict thyroid dysfunction. Control of inflammatory activity may be a protective measure against thyroid dysfunction. More large-scale prospective studies are necessary to further explore the correlation between SII and thyroid function and the role of obesity in this.

Thyroid dysfunction in children and adolescents affected by undernourished and overnourished eating disorders

Eating disorders (ED) are one of the most prevalent chronic disorders in adolescents and young adults, with a significantly increasing prevalence in younger children, particularly in girls. Even if obesity in essence is not framed as an eating disorder and has always been considered a separate pathology, ED and obesity could be considered part of a continuum. It has become evident that one condition can lead to another, such as binge eating disorder (BED) and bulimia nervosa, and that they share the same repercussions in terms of psychosocial, metabolic, and nutritional health. This narrative review aims to investigate the hypothalamic-pituitary-thyroid axis in undernourished and overnourished patients with ED, including obesity, in order to highlight the relationship between weight control and thyroid function and its effects and to consider therapeutic and preventive strategies in children and adolescents. Literature data report that thyroid alterations occur in patients with ED, both underweight and overweight, and represent a continuum of changes depending on the severity and time course of the disease involving the endocrine system. Considering the relevant role thyroid hormones (TH) play not only in energy expenditure (EE) but also in metabolic control and cardiovascular risks related to dysmetabolism and mood regulation, continuous monitoring of thyroid homeostasis in patients with ED is mandatory to prevent severe complications and to start early treatment when necessary.

Hunger & satiety signals: another key mechanism involved in the NAFLD pathway

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent metabolic disease, although prevalence could change according to region, nowadays is considered a public health problem whose real impact on the health system is unknown. NAFLD has a multifactorial and complex pathophysiology, due to this, developing a unique and effective pharmacological treatment has not been successful in reverting or avoiding the progression of this liver disease. Even though NAFLD pathophysiology is known, all actual treatments are focused on modifying or regulating the metabolic pathways, some of which interplay with obesity. It has been known that impairments in hunger and satiety signals are associated with obesity, however, abnormalities in these signals in patients with NAFLD and obesity are not fully elucidated. To describe these mechanisms opens an additional option as a therapeutic target sharing metabolic pathways with NAFLD, therefore, this review aims to describe the hormones and peptides implicated in both hunger-satiety in NAFLD. It has been established that NAFLD pharmacological treatment cannot be focused on a single purpose; hence, identifying interplays that lead to adding or modifying current treatment options could also have an impact on another related outcome such as hunger or satiety signals.

Changes in Urinary Iodine Levels Following Bariatric Surgery

OBJECTIVE

Obesity has become an epidemic in the United States. Although bariatric surgery can effectively achieve weight loss by altering the gastrointestinal tract, it commonly results in micronutrient deficiency, requiring supplementation. Iodine is an essential micronutrient for the synthesis of thyroid hormones. We aimed to investigate changes in urinary iodine concentrations (UIC) in patients following bariatric surgery.

METHODS

85 adults who underwent either laparoscopic sleeve gastrectomy or laparoscopic Roux-en-Y gastric bypass surgery were enrolled. At baseline and 3 months after surgery, we evaluated spot UIC and serum thyroid stimulating hormone (TSH), vitamin D, vitamin B12, ferritin, and folate levels. Participants provided a 24-hour diet recall for iodine-rich foods and information about multivitamin use at each time point.

RESULTS

There was a significant increase in median UIC (201 [120.0 - 288.5] vs 334.5 [236.3 - 740.3] μg/L; P < .001), a significant decrease in mean body mass index (44.0 ± 6.2 vs 35.8 ± 5.9; P < .001) and a significant decrease in TSH levels (1.5 [1.2 - 2.0] vs 1.1 [0.7 - 1.6] uIU/mL; P < .001) at 3 months postoperatively compared to baseline. Body mass index, UIC, and TSH levels before and after surgery did not differ based on the type of weight loss surgery.

CONCLUSION

In an iodine-sufficient area, bariatric surgery does not cause iodine deficiency nor clinically significant changes in thyroid function. Different surgical procedures with different anatomical alterations in the gastrointestinal tract do not significantly affect iodine status.

Prevalence of overweight and obesity in patients with major depressive disorder with anxiety: Mediating role of thyroid hormones and metabolic parameters

BACKGROUNDS

Anxiety is a common comorbidity in major depressive disorder (MDD); however, its role in overweight and obesity in MDD patients remains unclear. We examined the relationship between severe anxiety and overweight and obesity, as well as the mediating role of thyroid hormones and metabolic parameters in MDD patients.

METHODS

This cross-sectional study recruited 1718 first-episode drug-naïve MDD outpatients. All participants were rated on the Hamilton Depression Rating Scale for depression and Hamilton Anxiety Rating Scale for anxiety and measured in thyroid hormones and metabolic parameters.

RESULTS

A total of 218 (12.7 %) individuals had severe anxiety. The prevalence of overweight and obesity in patients with severe anxiety was 62.8 % and 5.5 %, respectively. Severe anxiety symptoms were associated with overweight (Odds Ratio [OR]: 1.47, 95 % CI: 1.08, 2.00) and obesity (OR: 2.10, 95 % CI: 1.07, 4.15). The association between severe anxiety and overweight was mainly attenuated by thyroid hormones (40.4 %), blood pressure (31.9 %), and plasma glucose (19.1 %). For obesity, the association with severe anxiety was mainly attenuated by thyroid hormones (48.2 %), blood pressure (39.1 %), and total cholesterol (28.2 %).

LIMITATIONS

Due to the cross-sectional design, no causal relationship could be derived.

CONCLUSIONS

Thyroid hormones and metabolic parameters can explain the risk of overweight and obesity associated with severe anxiety in MDD patients. These findings add to the knowledge of the pathological pathway of overweight and obesity in MDD patients with comorbid severe anxiety.

Serum Concentration of Growth Differentiation Factor 15 and Atherosclerosis among General Older Japanese Individuals with Normal Weight

Growth differentiation factor 15 (GDF-15), which modulates cellular energy balance, is reported to be positively associated with cardiovascular disease. However, there have been no reports about the association between serum GDF-15 concentration and atherosclerosis as evaluated by carotid intima-media thickness (CIMT) among the general population. A cross-sectional study of 536 Japanese individuals aged 60 to 69 years was conducted. To avoid the influence of abnormal cellular energy balance, this study only included participants who had a normal body mass index (BMI) and normal thyroid hormone (free thyroxine and free triiodothyronine) levels. A significant positive association between serum GDF-15 concentration and atherosclerosis was observed. In the sex- and age-adjusted model (Model 1), the odds ratio (OR) (95% confidence interval (CI)) for the logarithmic value of GDF-15 and atherosclerosis was 2.62 (1.67, 5.87). This association remained after adjusting for thyroid function and renal function (Model 2) and further adjusting for known cardiovascular risk factors (Model 3). The corresponding values were 2.61 (1.15, 5.93) for Model 2 and 2.49 (1.08, 5.71) for Model 3, respectively. Serum GDF-15 concentrations could help us to estimate the risk of atherosclerosis by indicating the status of cellular energy balance, which is related to mitochondrial activity among comparative healthy older individuals.

The relationship between serum superoxide dismutase and thyroid function in obese patients after Laparoscopic sleeve gastrectomy

To investigate the cross-sectional and longitudinal correlation between serum superoxide dismutase (SOD) levels and thyroid function with obesity before and after laparoscopic sleeve gastrectomy (LSG). Patients with morbid obesity (n = 219, 112 males and 107 females) who underwent LSG were selected and they were subdivided into normal levels of SOD (NSOD, n = 112) and high levels of SOD (HSOD, n = 107) according to the median value of SOD levels (183 U/mL). SOD and thyroid hormones were measured and compared at baseline, 3, 6, and 12 months after LSG. The HSOD group had lower body mass index (BMI), total thyroxine (TT4), and thyroid-stimulating hormone (TSH) than the NSOD group (p < 0.001, p = 0.031, p < 0.001, respectively). However, they had higher free triiodothyronine (FT3) and free thyroxine (FT4) (p = 0.019 and p = 0.017, respectively). SOD was significantly negatively associated with TSH and positively associated with FT4. Of all the patients, 22.31% (NSOD: 66.67%; HSOD: 33.33%) had subclinical hypothyroidism (SH), and there were lower SOD levels in the SH group. Preoperative SOD was a protective factor for SH. After LSG, SOD and FT4 levels were increased at 12 months after LSG, however, TSH, FT3, total triiodothyronine (TT3) and TT4 levels decreased compared to the preoperative levels at 3, 6, and 12 months in the SH group. Postoperative changes in FT4 and TT4 levels correlated with changes in SOD levels. SOD, which is correlated with thyroid hormones, protects against SH in patients with obesity. The improvement in thyroid function with SH after LSG may be related to increased SOD levels.

Prevalence and risk factors of thyroid dysfunction in outpatients with overweight or obese first-episode and drug-naïve major depressive disorder

BACKGROUND

Thyroid dysfunction is common in patients with major depressive disorder (MDD). However, few studies have examined risk factors for thyroid dysfunction in overweight or obese first-episode and drug-naïve (FEDN) MDD patients. This study aimed to investigate the prevalence and risk factors of thyroid dysfunction in FEDN MDD patients with comorbid high body mass index (BMI).

METHODS

A total of 1718 FEDN MDD patients were included. Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), and Positive and Negative Syndrome Scale (PANSS) positive subscale were used to assess the clinical symptoms of the patients. In addition, metabolic parameters and thyroid hormone levels were measured.

RESULTS

The prevalence of thyroid dysfunction was approximately 1.75 times higher in MDD patients with comorbid overweight or obesity (72.3 %) than in patients without high BMI (58.8 %). The HAMD score, HAMA score, systolic blood pressure (BP), fasting blood glucose (FBG), thyroid peroxidase antibody (TPOAb), total cholesterol (TC), high-density lipoprotein (HDL-C), and low-density lipoprotein (LDL-C), were risk factors for thyroid dysfunction in MDD patients with high BMI. The combination of HAMD, FBG, TC, LDL-C, and systolic BP had a high AUC value of 0.76 differentiating patients with and without thyroid dysfunction.

LIMITATION

Causality cannot be drawn due to cross-sectional design.

CONCLUSIONS

This study demonstrated a high prevalence of thyroid dysfunction in FEDN MDD patients with high BMI. Severity of depression and anxiety, levels of systolic BP, FBG, TPOAb, TC, HDL-C and LDL-C appear to be associated with thyroid dysfunction in FEDN MDD patients with high BMI.

Prepregnancy Body Mass Index and Risk of Differentiated Thyroid Cancer: A Prospective Cohort Study of More than 440,000 Danish Women

Background: High body mass index (BMI) has previously been associated with increased risk of differentiated thyroid cancer (DTC); however, only few studies have investigated the association with BMI in a large cohort assessed at a young age and with sufficient data on confounding factors. We assessed the association between excess body weight and the risk of DTC and papillary thyroid cancer (PTC) in a large cohort of young Danish women with substantial confounder control. Methods: We included all parous Danish women registered with a prepregnancy BMI ≥18.5 kg/m² during 2004-2016 in the Danish Medical Birth Registry in the study population. Cox proportional hazards regression models were used to estimate the hazard ratios (HRs) with confidence intervals (CIs) of DTC according to BMI. In subanalyses, we investigated PTC as a separate group. Analyses were adjusted for calendar time, education, smoking status, benign thyroid disease (BTD), type II diabetes, parity, and oral contraceptive use. In addition, we examined the association with increasing BMI stratified for previous BTD. Results: A total of 443,403 women were included in the study population, and the median age at baseline was 30.0 years. Altogether, 463 women were diagnosed with DTC during follow-up. Excess body weight was associated with a higher rate of DTC (overweight, BMI 25-29.9 kg/m²: HR = 1.54; CI 1.25-1.90. Obese, BMI ≥30 kg/m²: HR = 1.32; CI 1.00-1.75) compared with normal weight. Results were similar in PTC. In addition, we found an increased rate of DTC with increasing BMI, when investigating BMI as a continuous variable per 5 kg/m² increase (HR = 1.17; CI 1.07-1.27). The results were similar in women without previous BTD. Conclusions: Our study confirms that excess body weight is associated with an increased incidence of DTC and PTC in women.

Preventive effect of Ya'an Tibetan tea on obesity in rats fed with a hypercaloric high-fat diet revealed by gut microbiology and metabolomics studies

Ya'an Tibetan Tea (YATT) is a classic dark tea variety fermented with a unique geographical environment and traditional craftsmanship. Previous research indicates that it is beneficial for obesity and related metabolic disorders, but no systematic research currently reveals its precise mechanisms. This work investigated the preventive effect of YATT on obesity and the corresponding potential mechanisms by performing 16S rRNA gene sequencing and metabolomics studies. Our results demonstrated that YATT could significantly improve the body weight and fat deposition in hypercaloric high-fat diet (HFD)-induced obese rats, enhance antioxidant enzymes activity and reduce inflammation, and reverse the liver damage caused by an HFD. Moreover, 16S rRNA analysis showed that YATT could improve the intestinal microbial disorders caused by the HFD by significantly reversing the increase in Firmicutes/Bacteroidetes（F/B）ratio and the relative abundance of flora associated with the HFD, such as unclassified_Lachnospiraceae and Romboutsia flora. In addition, metabolomic analysis of cecum contents identified 121 differential metabolites, of which 19 were common to all experimental rats fed with and without a high-fat diet. Strikingly, 17 of the most prevalent 19 differential metabolites, including Theobromine, L-Valine, and Diisobutyl phthalate, were considerably reversed by YATT. Enrichment analysis of the metabolic pathways of these differential metabolites indicated that Caffeine metabolism, Phenylalanine metabolism, and Lysine degradation are the potential metabolic pathways responsible for the obesity prevention effect of YATT. Collectively, this work revealed that YATT has good potential for obesity prevention and the improvement of intestinal microbial communities, potentially due to the YATT-induced alterations in the metabolic pathways and functional metabolite levels of caffeine and amino acids. These results inform the material basis of YATT for obesity prevention and its mechanisms and provide essential insights for developing YATT as a healthy beverage for obesity prevention.

Radioactive Iodine-induced hypothyroidism interferes with the maturation of reproductive organs during puberty in immature female rats

Animal and human studies suggest that thyroid hormone may have critical roles in the development of the ovary. For example, thyroid deficiency disrupts the ovarian microarchitecture and menstrual cycle in neonate and adult women, respectively. Therefore, it is conceivable that thyroid deficiency might disrupt sexual maturation during the peri-pubertal period. To investigate the impact of radioactive iodine-induced thyroid deficiency on reproductive organs throughout puberty, immature female rats were given water containing radioactive iodine (0.37 MBq/g body weight) twice, on postnatal days 22 and 29. Radioactive iodine-induced hypothyroidism was revealed by low free thyroxin levels. Thyroid deficiency delayed the onset of vaginal opening, reduced ovarian weight and the number of medium-sized follicles and led to elongated uteri. However, there was no effect on the estrous cycle or absolute uterus weight. We conclude that radioactive iodine-induced thyroid deficiency delays sexual maturation and alters normal ovarian growth in peri-pubertal rats.

Body composition changes following total thyroidectomy: A one-year follow-up study

INTRODUCTION

Thyroid hormones play an important role in body weight regulation. In this study, we investigated which body composition parameters cause a change in body weight after total thyroidectomy.

MATERIALS AND METHOD

We performed a retrospective cohort study of a prospectively maintained database of patients who underwent total thyroidectomy. Demographics, thyroid function tests, indications for surgery, final pathology, and postoperative thyroid status were collected. Body composition analyses measured by the bioelectrical impedance analysis method were recorded at two-time points, 12 months apart.

RESULTS

Forty-four patients were included in the study with a mean age of 51.6 years. There were statistically significant increases in weight (p=0.049), body mass index (p=0.021), and fat mass (p=0.001) over time. While 12 patients (27.3%) lost or maintained weight, 32 patients (72.7%) gained weight. There was no significant difference in age, sex, preoperative thyroid function tests, postoperative thyroid status, or pathology between those who gained weight and those who did not. Although changes in all body composition parameters were higher in males than in females, these differences were not significant overall. Multivariable regression analysis revealed a significant positive relationship between increase in fat mass and baseline free-T₃ (p=0.041) and found that lower baseline percent body fat was a significant factor for greater fat mass gain (p=0.016). However, no predictors of change in weight were identified.

CONCLUSION

We conclude that total thyroidectomy results in a significant change in body weight and fat mass. Higher free-T₃ and lower percent body fat at baseline were significant factors of fat mass gain.

The Correlation Between Health Risk Factors and Diabesity and Lipid Profile Indicators: The Role Mediator of TSH

Introduction

Obesity in adults is a problem, particularly when paired with other metabolic abnormalities. Previous research have linked various screening approaches to diabetes, but additional evidence points to the relevance of combining diabetes screening methods with obesity and its effects. This research examined the impact of thyroid hormones (TSHs) and health risk factors (HRFs) in screening for obesity and diabetes in Chinese populations, and whether age can modulate this association.

Methods

From March to July 2022, the Hefei Community Health Service Center connected with the First Affiliated Hospital of Anhui Medical University was chosen, and the multi-stage cluster sample approach was utilized to test adults aged 21-90 in each community. Latent category analysis (LCA) was performed to investigate the clustering patterns of HRFs. A one-way ANOVA was used to examine waist circumference (WC), biochemical markers, and general data. Furthermore, multivariate logistic regression analysis was utilized to investigate the relationship between health risk variables and WC.

Results

A total of 750 individuals without a history of major problems who had a community health physical examination were chosen, with missing data greater than 5% excluded. Finally, 708 samples were included in the study with an effective rate of 94.4%. The average WC was (90.0±10.33) cm, the prevalence in the >P₇₅, P₅₀~P₇₅, P₂₅~P₅₀, and ≤P₂₅ groups were 24.7%, 18.9%, 28.7% and 27.7%, respectively. The average TSH was (2.76±2.0) μIU/mL. Male (β=1.91), HOMA-IR (β=0.06), TyG (β=2.41), SBP (β=0.08), TG (β=0.94) and UA (β=0.03) were more likely to have a higher prevalence of WC level. The analyses revealed significant correlations between HRFs, TSH, age, other metabolic indexes and WC (P < 0.05).

Discussion

Our findings suggest that the quality of metabolic-related indicators used to successfully decrease diabetes in Chinese individuals with high HRFs levels should be prioritized. Comprehensive indicators might be a useful and practical way for measuring the metabolic evolution of diabetes level levels.

Gender Differences in the Relationship Between Food Insecurity and Body Mass Index Among Adults in the USA

BACKGROUND

In the USA, nearly 40% of adults ≥ 20 years have a body mass index (BMI) ≥ 30, and 11% of households are reported as food insecure. In adults, evidence shows women are more likely than men to be food insecure. Among adults with food insecurity, differences in BMI exist between men and women with women reporting higher BMI. Factors associated with this difference in BMI between genders are less understood.

OBJECTIVE

The aim of this study was to assess gender differences in the relationship between food insecurity and BMI.

DESIGN

Hierarchical models were analyzed using a general linear model by entering covariates sequentially in blocks (demographics, lifestyle behaviors, comorbidities, and dietary variables) and stratified by gender.

PARTICIPANTS

The sample included 25,567 adults in the USA from the National Health and Nutrition Examination Survey (NHANES), 2005-2014.

MAIN MEASURES

The dependent variable was BMI, and food insecurity was the primary predictor.

KEY RESULTS

Approximately 51% of the sample was women. Food insecure women were significantly more likely to have higher BMI compared to food secure women in the fully adjusted model after controlling for demographics (β = 1.79; 95% CI 1.17, 2.41); demographic and lifestyle factors (β = 1.79; 95% CI 1.19, 2.38); demographic, lifestyle, and comorbidities (β = 1.21; 95% CI 0.65, 1.77); and demographic, lifestyle, comorbidities, and dietary variables (β = 1.23; 95% CI 0.67, 1.79). There were no significant associations between food insecure and food secure men in the fully adjusted model variables (β = 0.36; 95% CI - 0.26, 0.98).

CONCLUSION

In this sample of adults, food insecurity was significantly associated with higher BMI among women after adjusting for demographics, lifestyle factors, comorbidities, and dietary variables. This difference was not observed among men. More research is necessary to understand this relationship among women.

Associations between serum perfluoroalkyl acid (PFAA) concentrations and health related biomarkers in firefighters

Firefighters who used aqueous film forming foam in the past have experienced elevated exposures to perfluoroalkyl acids (PFAAs). The objective of this study was to examine the associations between clinical chemistry endpoints and serum concentrations of perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS) and perfluorooctane sulfonate (PFOS) in firefighters. Multiple linear regression was used to assess relationships between PFAA serum concentrations and biochemical markers for cardiovascular disease, kidney-, liver- and thyroid function, in a cross-sectional survey of 783 firefighters with elevated levels of PFHxS, PFHpS and PFOS in relation to the most recently reported levels in the general Australian population. Linear logistic regression was used to assess the odds ratios for selected self-reported health outcomes. Repeated measures linear mixed models were further used to assess relationships between PFAAs and biomarkers for cardiovascular disease and kidney function longitudinally in a subset of the firefighters (n = 130) where serum measurements were available from two timepoints, five years apart. In the cross-sectional analysis, higher levels of all PFAAs were significantly associated with higher levels of biomarkers for cardiovascular disease (total-cholesterol, and LDL-cholesterol). For example, doubling in PFOS serum concentration were associated with increases in total cholesterol (β:0.111, 95% confidence interval (95%CI): 0.026, 0.195 mmol/L) and LDL-cholesterol (β: 0.104, 95%CI:0.03, 0.178 mmol/L). Doubling in PFOA concentration, despite not being elevated in the study population, were additionally positively associated with kidney function marker urate (e.g., β: 0.010, 95%CI; 0.004, 0.016 mmol/L) and thyroid function marker TSH (e.g., β: 0.087, 95%CI: 0.014, 0.161 mIU/L). PFAAs were not associated with any assessed self-reported health conditions. No significant relationships were observed in the longitudinal analysis. Findings support previous studies, particularly on the association between PFAAs and serum lipids.

TSH and FT4 Reference Intervals in Pregnancy: A Systematic Review and Individual Participant Data Meta-Analysis

CONTEXT

Interpretation of thyroid function tests during pregnancy is limited by the generalizability of reference intervals between cohorts due to inconsistent methodology.

OBJECTIVE

(1) To provide an overview of published reference intervals for thyrotropin (TSH) and free thyroxine (FT4) in pregnancy, (2) to assess the consequences of common methodological between-study differences by combining raw data from different cohorts.

METHODS

(1) Ovid MEDLINE, EMBASE, and Web of Science were searched until December 12, 2021. Studies were assessed in duplicate. (2) The individual participant data (IPD) meta-analysis was performed in participating cohorts in the Consortium on Thyroid and Pregnancy.

RESULTS

(1) Large between-study methodological differences were identified, 11 of 102 included studies were in accordance with current guidelines; (2) 22 cohorts involving 63 198 participants were included in the meta-analysis. Not excluding thyroid peroxidase antibody-positive participants led to a rise in the upper limits of TSH in all cohorts, especially in the first (mean +17.4%; range +1.6 to +30.3%) and second trimester (mean +9.8%; range +0.6 to +32.3%). The use of the 95th percentile led to considerable changes in upper limits, varying from -10.8% to -21.8% for TSH and -1.2% to -13.2% for FT4. All other additional exclusion criteria changed reference interval cut-offs by a maximum of 3.5%. Applying these findings to the 102 studies included in the systematic review, 48 studies could be used in a clinical setting.

CONCLUSION

We provide an overview of clinically relevant reference intervals for TSH and FT4 in pregnancy. The results of the meta-analysis indicate that future studies can adopt a simplified study setup without additional exclusion criteria.

Exploratory analysis of the associations between neonicotinoids and measures of adiposity among US adults: NHANES 2015-2016

BACKGROUND

Toxicology studies suggest that neonicotinoids may be associated with adiposity development via thyroid hormone disruption and increased oxidative stress. Prior epidemiological studies report mixed results for the association between neonicotinoids and adiposity measures.

OBJECTIVE

To examine the association between detectable concentrations of parent neonicotinoids (imidacloprid, acetamiprid, clothianidin) and neonicotinoid metabolites (5-hydroxy-imidacloprid, N-desmethyl-acetamiprid) with adiposity measures among US adults, and whether sex modifies the associations for neonicotinoid metabolites with adiposity.

METHODS

National Health and Nutrition Examination Survey (NHANES) 2015-2016 data was utilized to estimate covariate-adjusted associations between detectable neonicotinoids and fat mass index (FMI), lean mass index (LMI), waist circumference, body fat percentage, and body mass index (BMI) using multiple linear regression. We estimated incidence rate ratios (IRRs) for overweight or obese status with detectable neonicotinoid concentrations using Poisson's modified regression. Sampling strategies were accounted for in the regression models.

RESULTS

Detectable levels of acetamiprid were associated with a decrease in FMI (β = -3.17 kg/m², 95% CI [-4.79, -1.54]), LMI (β = -3.17 kg/m², 95% CI [-5.17, -1.17]), body fat percentage (β = -4.41, 95% CI [-8.20, -0.62]), waist circumference (β = -9.80 cm, 95% CI [-19.08, -0.51]), and BMI (β = -3.88kg/m², 95% CI [-7.25, -0.51]) among adults. In contrast, detectable levels of 5-hydroxy-imidacloprid were associated with greater rates of being overweight/obese (IRR = 1.11, 95% CI [1.04, 1.18)) and increased LMI (β = 0.67 kg/m², 95% CI [0.04, 1.29]). Sex modified the association between N-desmethyl-acetamiprid and LMI (p_int = 0.075) with a positive association among males (β = 1.14 kg/m², 95% CI [0.38, 1.90]), and an insignificant inverse association in females. Sex also modified the association for N-desmethyl-acetamiprid with FMI (p_int = 0.095) and body fat percentage (p_int = 0.072), with suggestive evidence showing positive associations for males and inverse associations for females.

CONCLUSION

Detectable concentrations of acetamiprid were inversely associated with adiposity, while there were mixed findings for 5-hydroxy-imidacloprid. Findings suggest sex differences, though results are not clear with regard to the directionality of the association by sex.

Association between Thyroid Cancer and Weight Change: A Longitudinal Follow-Up Study

BACKGROUND

The purpose of this study was to evaluate body mass index (BMI) and systolic blood pressure (SBP)/diastolic blood pressure (DBP) between Korean adults who underwent thyroidectomy and comparison groups.

METHODS

Data were included from the Korean National Health Insurance Service-Health Screening Cohort (2002-2015). BMI and SBP/DBP were measured before thyroidectomy, 1 and 2 years after thyroidectomy (n = 1995 in study I, n = 2162 in study II), comparing 1:4 matched participants (n = 7980 in study I, n = 8648 in study II). The paired t-test and linear mixed model were used to identify the differences between groups.

RESULTS

DBP in both thyroid cancer II and comparison II group were significantly lower after thyroidectomy than before thyroidectomy. However, the interaction effect of thyroidectomy in study I and study II did not reach statistical significance.

CONCLUSION

BMI, SBP and DBP were not significantly different between the thyroidectomy group and the matched comparison group.

The Role of Thyroid Hormones on Skeletal Muscle Thermogenesis

Nowadays obesity becomes a significant global problem. Hence, recently more and more attention has been paid to substances present in the body that have a significant impact on metabolic processes and thermogenesis, in the context of their potential use in the prevention and treatment of obesity. It is well known that the relationship between thyroid hormones and obesity is multilayered, however recently, more and more information about the possible relation between thyroid hormones and muscle metabolism has been published. The aim of this review is to present the most updated information on the physiological impact of thyroid hormones on muscle tissue, as well as pathological changes related to the occurrence of various types of thyroid disorders, including hypothyroidism, hyperthyroidism and sick euthyroid syndrome. However, the data in humans still remains insufficient, and further studies are needed to fully explore the thyroid-muscle cross-talk.

Maternal Obesity in Twin Pregnancy: The Role of Nutrition to Reduce Maternal and Fetal Complications

There are more and more obese mothers with twin gestations. For a long time before, the responses of lymphocytes and platelets in obese women can cause a low-grade inflammation. In addition, a proper control of gestational weight gain would improve the outcomes in mothers with high pre-gestational body mass index (BMI). In women with high pre-gestational BMI and twin pregnancy, our aims were to explore the biochemical and hematological parameters and to study the rate of obstetric adverse outcomes. This was an observational and retrospective study conducted in the Hospital Universitario La Paz (Madrid, Spain). We included 20 twin pregnancies as the lean group (BMI = 18.5–24.9 kg/m²), homogeneous in the maternal age and ethnicity, and having parity with other 20 twin pregnancies as the obese group (BMI ≥ 30 kg/m²). The maternal data and maternal, fetal, obstetric, and neonatal complications were collected from the medical records. In the first and third trimester of pregnancy, the biochemical and hematological parameters of the blood were assayed. In this cohort, gestational weight gain was significantly lower in the obese than lean group. In the first trimester, the hemoglobin levels in obese women (12.1 ± 0.8 g/dL) were lower than lean women (12.6 ± 0.7 g/dL; p-Value = 0.048). In addition, the tendency of glucose levels, TSH levels and platelets was to increase in obese compared to lean women. In the third trimester, the TSH levels were higher in obese (3.30 ± 1.60 mUI/L) than lean women (1.70 ± 1.00 mUI/L; p-Value = 0.009). Furthermore, there was a tendency for levels of platelets and lymphocytes to increase in obese compared to lean women. No significant differences were detected in the rate of maternal, fetal, obstetrical, and neonatal complications between the groups. The hemoglobin, platelets, lymphocytes and TSH levels need further investigation to understand potential subclinical inflammation in obese women. Furthermore, obese women with twin pregnancies should follow-up with a specialist nutritionist, to help them control their gestational weight gain with appropriate dietary measures.

Obesity history, physical exam, laboratory, body composition, and energy expenditure: An Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2022

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on History, Physical Exam, Body Composition and Energy Expenditure is intended to provide clinicians an overview of the clinical and diagnostic evaluation of patients with pre-obesity/obesity.

Methods

The scientific information for this CPS is based upon published scientific citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

This CPS outlines important components of medical, dietary, and physical activity history as well as physical exams, with a focus on specific aspects unique to managing patients with pre-obesity or obesity. Patients with pre-obesity/obesity benefit from the same preventive care and general laboratory testing as those without an increase in body fat. In addition, patients with pre-obesity/obesity may benefit from adiposity-specific diagnostic testing - both generally and individually - according to patient presentation and clinical judgment. Body composition testing, such as dual energy x-ray absorptiometry, bioelectrical impedance, and other measures, each have their own advantages and disadvantages. Some patients in clinical research, and perhaps even clinical practice, may benefit from an assessment of energy expenditure. This can be achieved by several methods including direct calorimetry, indirect calorimetry, doubly labeled water, or estimated by equations. Finally, a unifying theme regarding the etiology of pre-obesity/obesity and effectiveness of treatments of obesity centers on the role of biologic and behavior efficiencies and inefficiencies, with efficiencies more often associated with increases in fat mass and inefficiencies more often associated with decreases in fat mass.

Conclusion

The Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on History, Physical Exam, Body Composition and Energy Expenditure is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of pre-obesity/obesity.

Histological pattern and gene expression profiling of thyroid tissue in subjects with obesity

PURPOSE

Subjects with obesity may exhibit an increase in serum TSH concentrations. Several mechanisms have been proposed to explain this association, including the presence of a compensatory mechanism to counterbalance an accelerated turnover of thyroid hormones in subjects with obesity. This study aimed at evaluating whether the thyroids of subjects with obesity differs from those of normal-weight individuals regarding histology and gene expression profiling.

METHODS

Ninety-eight patients were selected among those scheduled for thyroidectomy. At histology, thyroid tissue samples were investigated for the presence of adipocytes and/or lymphocyte infiltration. In a subset of patients, the expression at mRNA level of several genes involved in metabolic pathways and immune cell-related mechanisms was quantified by NanoString Technology.

RESULTS

The presence of adipose cells was documented in thyroid specimens from 40% normal weight, 52.9% overweight and 73.5% patients with obesity. The number of infiltrating adipocytes was greater in specimens of patients with overweight or obesity compared to normal weight. The lymphocytes common antigen (CD45) and mast cell (MC) scores, and the number of CD3+ and CD8+ lymphocytes were higher in patients with overweight and obesity than in normal-weight subjects. Several genes involved in metabolic pathways were differently expressed in patients with overweight or obesity compared to normal weight, with upregulation of Leptin receptor and downregulation of Fatty Acid-Binding Protein 5.

CONCLUSIONS

Increased BMI is associated with adipocyte and lymphocyte infiltration of the thyroid, not related to an autoimmune process, which might affect thyroid function in subjects with obesity. A differential gene expression profiling of metabolic and immune pathways in thyroid tissues of patients with obesity was also observed.

Association Between Elevated Thyroid Peroxidase Antibody and Abdominal Fat Distribution in Patients with Type 2 Diabetes Mellitus

OBJECTIVE

Obesity and autoimmune thyroid disease (AITD) are both common disorders in the general population, which are major drivers for adverse medical conditions. While an interaction between thyroid function and visceral obesity is thought to exist, but very few studies have examined the relationship between AITD and visceral obesity, especially in the patients with type 2 diabetes mellitus (T2DM). In the present study, we investigated the association between elevated thyroid peroxidase antibody (TPOAb) titer and visceral fat area in T2DM patients.

METHODS

A total of 390 T2DM patients who met the criteria for admission and joined the National Metabolic Management Center (MMC) in the Zhejiang Provincial People's Hospital from April 2020 to December 2020 were enrolled in this study. The participants were divided into two groups based on visceral obesity. Thyroid function, thyroid associated antibody and other metabolic indicators were measured by blood tests. The visceral fat area (VFA) and the subcutaneous fat area (SFA) were measured by bioelectrical impedance analysis.

RESULTS

There were 185 participants (47.4%) had visceral obesity. The positive rate of TPOAb was significantly higher in T2DM patients with visceral obesity (12.97% vs 5.37%, p < 0.01). Free triiodothyronine (FT3) and thyroid-stimulating hormone (TSH) were both significantly higher in T2DM patients with visceral obesity (p < 0.05). The increased TPOAb titer was significantly positively correlated with visceral fat area (r = 0.175, p < 0.01). Binary logistic analysis showed that the positive rate of TPOAb was associated with an increased risk of visceral obesity [(OR) 4.258, 95% confidence interval (CI) 1.594, 11.375, p = 0.004].

CONCLUSION

TPOAb-positive is more common in T2DM patients with visceral obesity, which has some effects on visceral obesity independent of thyroid function. This suggests that elevated TPOAb titer is a predictor of visceral obesity in T2DM patients.

The pattern of TSH and fT4 levels across different BMI ranges in a large cohort of euthyroid patients with obesity

PURPOSE

A multifold association relates the hypothalamo-pituitary-thyroid axis to body weight. The potential underlying mechanisms are incompletely understood. Further, the mild severity of obesity and the small proportion of individuals with obesity in so far published cohort studies provide little insights on metabolic correlates of thyroid function in obesity.

METHODS

We retrospectively enrolled 5009 adults with obesity (F/M, 3448/1561; age range, 18-87 years; BMI range, 30.0-82.7 kg/m²), without known thyroid disease in a study on TSH and fT4 levels, lipid profile, glucose homeostasis and insulin resistance, anthropometric parameters including BIA-derived fat mass (%FM) and fat-free mass (FFM).

RESULTS

The overall reference interval for TSH in our obese cohort was 0.58-5.07 mIU/L. As subgroups, females and non-smokers showed higher TSH levels as compared to their counterparts (p<0.0001 for both), while fT4 values were comparable between groups. There was a significant upward trend for TSH levels across incremental BMI classes in females, while the opposite trend was seen for fT4 levels in males (p<0.0001 for both). Expectedly, TSH was associated with %FM and FFM (p<0,0001 for both). TSH and fT4 showed correlations with several metabolic variables, and both declined with aging (TSH, p<0.0001; fT4, p<0.01). In a subgroup undergoing leptin measurement, leptin levels were positively associated with TSH levels (p<0.01). At the multivariable regression analysis, in the group as a whole, smoking habit emerged as the main independent predictor of TSH (β=-0.24, p<0.0001) and fT4 (β=-0.25, p<0.0001) levels. In non-smokers, %FM (β=0.08, p<0.0001) and age (β=-0.05, p<0.001) were the main significant predictors of TSH levels. In the subset of nonsmokers having leptin measured, leptin emerged as the strongest predictor of TSH levels (β=0.17, p<0.01).

CONCLUSIONS

Our study provides evidence of a gender- and smoking-dependent regulation of TSH levels in obesity.

The role of purslane in modulating diverse effects of high fat diet on biochemical, histological, and molecular parameters of rats' liver

Consuming a high-fat diet causes a harmful accumulation of fat in the liver, which may not reverse even after switching to a healthier diet. Different reports dealt with the role of purslane as an extract against high-fat diet; meanwhile, it was necessary to study the potential role of fresh purslane as a hypolipidemic agent. This study is supposed to investigate further the potential mechanism in the hypolipidemic effect of fresh purslane, by measuring cholesterol 7a-hydroxylase (CYP7A1) and low-density lipoprotein receptor (Ldlr). Rats were divided into two main groups: the first one is the normal control group (n=7 rats) and the second group (n=28 rats) received a high fat diet for 28 weeks to induce obesity. Then the high fat diet group was divided into equal four subgroups. As, the positive control group still fed on a high fat diet only. Meanwhile, the other three groups were received high-fat diet supplemented with a different percent of fresh purslane (25, 50 and 75%) respectively. At the end of the experiment, rats were sacrificed and samples were collected for molecular, biochemical, and histological studies. Current study reported that, supplementation of fresh purslane especially at a concentration of 75% play an important role against harmful effects of high-fat diet at both cellular and organ level, by increasing CYP7A1 as well as Ldlr mRNA expression. Also, there were an improvement on the tested liver functions, thyroid hormones, and lipid profile. Fresh purslane plays the potential role as a hypolipidemic agent via modulation of both Ldlr and Cyp7A, which will point to use fresh purslane against harmful effects of obesity.

The Association between the Dietary Inflammatory Index and Thyroid Function in U.S. Adult Males

Thyroid function has a close link with inflammation. However, it is still unknown whether the dietary inflammatory potential is associated with thyroid function. We aimed to assess the relationship among them using the data from the National Health and Nutrition Examination Survey (NHANES). This study was a cross-sectional study, where weighted multivariable linear regression, subgroup analyses, and interaction terms were employed. Thyroid function was assessed by eight indexes, including total and free T4 and T3, Tg, TgAb, TPOAb, and TSH. A total of 2346 male participants aged ≥20 years with an average age of 50.74 ± 17.68 years were enrolled. The mean DII score among participants was −0.46 ± 1.73, ranging from −4.12 to 4.41, and mean total thyroxine (T4) was 7.61 ± 1.51 μg/dL. We found a positive association between DII and total T4 (β = 0.07; p = 0.0044). Using subgroup analysis, this association became stronger in both the iodine-deficient and obese group (iodine-deficient group: β = 0.15, p < 0.0001; obese group: β = 0.14, p < 0.0001). In conclusion, men adhering to a more pro-inflammatory diet appeared to have higher total T4 levels. However, these hormone variations were still within the normal clinical range and more well-designed studies are still needed to validate the causal relationship between DII and thyroid function.

Quantitative Structure-Activity Relationship Modeling of the Amplex Ultrared Assay to Predict Thyroperoxidase Inhibitory Activity

The thyroid system plays a major role in the regulation of several physiological processes. The dysregulation of the thyroid system caused by the interference of xenobiotics and contaminants may bring to pathologies like hyper- and hypothyroidism and it has been recently correlated with adverse outcomes leading to cancer, obesity, diabetes and neurodevelopmental disorders. Thyroid disruption can occur at several levels. For example, the inhibition of thyroperoxidase (TPO) enzyme, which catalyses the synthesis of thyroid hormones, may cause dysfunctions related to hypothyroidism. The inhibition of the TPO enzyme can occur as a consequence of prolonged exposure to chemical compounds, for this reason it is of utmost importance to identify alternative methods to evaluate the large amount of pollutants and other chemicals that may pose a potential hazard to the human health. In this work, quantitative structure-activity relationship (QSAR) models to predict the TPO inhibitory potential of chemicals are presented. Models are developed by means of several machine learning and data selection approaches, and are based on data obtained in vitro with the Amplex UltraRed-thyroperoxidase (AUR-TPO) assay. Balancing methods and feature selection are applied during model development. Models are rigorously evaluated through internal and external validation. Based on validation results, two models based on Balanced Random Forest (BRF) and K-Nearest Neighbours (KNN) algorithms were selected for a further validation phase, that leads predictive performance (BA = 0.76-0.78 on external data) that is comparable with the reported experimental variability of the AUR-TPO assay (BA ∼0.70). Finally, a consensus between the two models was proposed (BA = 0.82). Based on the predictive performance, these models can be considered suitable for toxicity screening of environmental chemicals.