Thyroid function, body mass index, and metabolic risk markers in euthyroid adults: a cohort study

Thyroid-Related Hormones Changes Predict Changes in Anthropometric Measures and Incidence of Obesity in Chinese Euthyroid Persons

The purpose of this study was to investigate the correlation of thyroid-related hormones changes within the reference range with the changes in anthropometric measures and incidence of obesity. The study included 4850 subjects with normal thyroid-related hormones at baseline and at follow-up. We evaluated the relationship of changes in thyroid-related biomarkers with anthropometric measures changes and incidence of obesity. In euthyroid persons, changes in serum thyroid stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) concentrations and FT3/FT4 ratio were independent predictors of changes in body mass index (BMI) and waist circumference (WC) in men, changes in serum FT3 and FT4 concentrations and FT3/FT4 ratio were independent predictors of changes in BMI and WC in women. Every single unit increment in ΔFT3/FT4 was accompanied by a 7.144 and 7.572 times risk of having obesity in men and women, respectively. Every single unit decrement in ΔFT4 was accompanied by a 21.0% and 26.9% lower risk of having obesity in men and women, respectively. In conclusion, in euthyroid individuals, changes in thyroid-related hormones were associated with anthropometric measures changes and incidence of obesity.

Normative range of various serum hormonal parameters among Indian women of reproductive age: ICMR-PCOS task force study outcome

Background

The hormonal profile varies considerably with age, gender, ethnicity, diet or physiological state of an individual. Limited population-specific studies have studied the variations in hormonal parameters among apparently healthy women. We aimed to analyse the biological reference interval for various hormonal parameters in the reproductive-aged healthy Indian women.

Methods

Out of 3877 participants that were clinically evaluated, 1441 subjects were subjected to laboratory investigations. All participants underwent a detailed clinical, biochemical and hormonal profiling. The hormone analysis was carried out at a single centre using a uniform methodology. Among the participants evaluated for biochemical and hormonal parameters, subjects that presented any abnormal profile or had incomplete investigations (n = 593) were excluded for further analysis.

Findings

The mean age (±SD) of the subjects retained in the final analysis (n = 848) was 29.9 (±6.3) years. In the present study, the biological reference interval (2.5th-97.5th centile) observed were: serum T4: μg/dL (5.23-12.31), TSH: μg/mL (0.52-4.16) and serum prolactin: ng/mL (5.13-37.35), LH: mIU/mL (2.75-20.68), FSH: mIU/mL 2.59-15.12), serum total testosterone: ng/mL (0.06-0.68), fasting insulin: mIU/mL (1.92-39.72), morning cortisol: μg/dL (4.71-19.64), DHEAS:μg/dL (50.61-342.6) and SHBG: nmol/L (21.37-117.54). Unlike T4, TSH, LH, and E2, the biological reference interval for prolactin, FSH, testosterone, C-peptide insulin and DHEAS varied when the subjects were stratified by age (p < 0.05). The comparative analysis showed marginal differences in the normative ranges for the hormones analysed among different populations.

Interpretation

Our first large composite data on hormonal measures will benefit future endeavours to define biological reference intervals in reproductive-aged Indian women.

Funding

The study was financially supported by the grant-in-aid from ICMR vide file No:5/7/13337/2015-RBMH.

Circulating free T3 associates longitudinally with cardio-metabolic risk factors in euthyroid children with higher TSH

Introduction

Thyroid hormones play major roles in the regulation of body composition and metabolism, and therefore, the relationship between thyroid hormones and cardio-metabolic risk has been extensively studied in adults. In this study, we aimed to test whether free triiodothyronine (fT3) associates longitudinally with cardio-metabolic risk factors in euthyroid children.

Methods

A prospective study cohort of 599 apparently healthy school-age children were assessed at baseline (mean age 8.1 ± 2.1 years), of whom 270 children were also assessed at follow-up (4 years later). Circulating thyroid-stimulating hormone (TSH), free thyroxine (fT4), and fT3 were measured, and cardio-metabolic risk was assessed by means of body mass index (BMI), waist circumference, visceral fat (by ultrasound), blood pressure, circulating lipids, and homeostasis model assessment of insulin resistance (HOMA-IR) index, both at baseline and at follow-up.

Results

All studied children had normal thyroid function tests. Independent associations between baseline fT3 and both baseline and follow-up BMI, systolic blood pressure, mean arterial blood pressure, triglycerides, and HOMA-IR were found using multivariate regression analysis (adjusting for sex and baseline age and BMI). Analyses of effect sizes showed that for each 1 unit-increase in baseline fT3 (pg/ml), follow-up BMI-standard deviation score (SDS) increased by 0.31 units (z-score) and systolic blood pressure by 6.6 units (mmHg). The observed longitudinal associations were more robust in children belonging to the upper TSH tertile who showed higher TSH levels and were characterized by weighing more and having the highest fT3 levels. In these children, for each 1 unit-increase in baseline fT3 (pg/ml), follow-up BMI-SDS increased by 0.67 units (z-score) and systolic blood pressure by 10.2 units (mmHg).

Conclusions

Circulating fT3 associates longitudinally with cardio-metabolic risk factors in euthyroid children with higher TSH. The observed associations of thyroid hormones in these children could conceivably respond to a homeostatic attempt to reduce their cardio-metabolic risk.

High free triiodothyronine, and free-triiodothyronine-to-free-thyroxine ratio are associated with metabolic syndrome in a euthyroid employee population: the Zhejiang Zhenhai study

Objective

The aim of this study was to elaborate the link of thyroid hormones (THs) and metabolic syndrome (MetS) in a Chinese euthyroid employee population with MetS component(s).

Methods

An annual health checkup was performed on employees in 2019. Anthropometric parameters, metabolic parameters, and thyroid function were measured. A questionnaire was used in conjunction with Zhenhai Lianhua Hospital database to receive employees' medication records and thyroid surgical history records.

Results

A total of 5486 eligible employees were included; the prevalence of MetS was generally higher in males than in females (38.9 vs. 30.4%, P < 0.001). Among employees with central obesity, hypertriglyceridemia, hyperglycemia, hypertension, and low high-density lipoprotein cholesterol (HDL-C), the prevalence of MetS was 68.8, 63.6, 68.2, 48.8, and 60.0% in males and 72.6, 63.3, 61.3, 42.3, and 42.3% in females, respectively. Logistic regression analysis showed that thyroid-stimulating hormone and free thyroxine (FT4) quartiles had no significant impact on MetS. Free triiodothyronine/free thyroxine (FT3/FT4) and free triiodothyronine (FT3)) quartiles were positively associated with the increased odds ratio (OR) for MetS and dyslipidemia (hypertriglyceridemia and low HDL-C), regardless of gender. In males, FT3 and FT3/FT4 quartiles were positively associated with the OR for central obesity, whereas FT4 quartiles were negatively associated; both FT3 and FT4 quartiles were positively associated with increased OR of hyperglycemia, while similar results were not observed in females. Interaction analysis indicated no significant effect of gender and TH interactions on risk of MetS.

Conclusion

High FT3 and FT3/FT4 were strongly linked with MetS and dyslipidemia in our study, even in the euthyroid individuals. Tighter control of thyroid function was necessary for those with preexisting MetS component(s).

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.

Age-related variation in thyroid function - a narrative review highlighting important implications for research and clinical practice

BACKGROUND

Thyroid hormones are key determinants of health and well-being. Normal thyroid function is defined according to the standard 95% confidence interval of the disease-free population. Such standard laboratory reference intervals are widely applied in research and clinical practice, irrespective of age. However, thyroid hormones vary with age and current reference intervals may not be appropriate across all age groups. In this review, we summarize the recent literature on age-related variation in thyroid function and discuss important implications of such variation for research and clinical practice.

MAIN TEXT

There is now substantial evidence that normal thyroid status changes with age throughout the course of life. Thyroid stimulating hormone (TSH) concentrations are higher at the extremes of life and show a U-shaped longitudinal trend in iodine sufficient Caucasian populations. Free triiodothyronine (FT3) levels fall with age and appear to play a role in pubertal development, during which it shows a strong relationship with fat mass. Furthermore, the aging process exerts differential effects on the health consequences of thyroid hormone variations. Older individuals with declining thyroid function appear to have survival advantages compared to individuals with normal or high-normal thyroid function. In contrast younger or middle-aged individuals with low-normal thyroid function suffer an increased risk of adverse cardiovascular and metabolic outcomes while those with high-normal function have adverse bone outcomes including osteoporosis and fractures.

CONCLUSION

Thyroid hormone reference intervals have differential effects across age groups. Current reference ranges could potentially lead to inappropriate treatment in older individuals but on the other hand could result in missed opportunities for risk factor modification in the younger and middle-aged groups. Further studies are now needed to determine the validity of age-appropriate reference intervals and to understand the impact of thyroid hormone variations in younger individuals.

Type 2 Diabetes Mellitus Coincident with Clinical and Subclinical Thyroid Dysfunctions Results in Dysregulation of Circulating Chemerin, Resistin and Visfatin

The alterations of circulating adipocytokines have been reported in thyroid diseases or type 2 diabetes mellitus (T2DM), but such data in T2DM coincident with clinical and subclinical thyroid-dysfunctions are limited, and remain to be investigated. We studied the changes in serum chemerin, resisitin and visfatin in T2DM patients with thyroid dysfunctions, and their association with inflammatory and insulin resistance-markers. A total of 272 female and male Iranian participants were selected and divided into six groups: the euthyroid group, T2DM, T2DM coincident with clinical and sub clinical hypothyroidism (SC-HO, and C-HO), and T2DM coincident with clinical and sub clinical hyperthyroidism (SC-HR, C-HR).Demographic characteristics, serum levels of adipocytokines, thyroid hormones, inflammatory factors (IL1-β, IL-6 and CRP) and insulin resistance-markers were determined in all participants. T2DM patients with clinical thyroid dysfunctions showed higher levels of circulating resistin, visfatin, chemerin and inflammatory factors, compared with the T2DM group and T2DM coexisted with subclinical thyroid diseases. No significant differences were observed in circulating adipocytokines and inflammatory markers between T2DM coexisting with subclinical thyroid diseases and those without thyroid dysfunctions. Our results revealed that clinical thyroid dysfunction in T2DM patients was associated with elevated levels of circulating resistin, chemerin, visfatin and inflammatory factors, while no such alteration was detected in T2DM coincident with subclinical thyroid dysfunction.

Serum lipid profile in relation to free thyroxine and the effect of levothyroxine treatment on lipids in patients with isolated hypothyroxinemia during pregnancy: a single-center retrospective study

BACKGROUND

Thyroid function is widely considered a lipid metabolism regulator. However, studies on lipid metabolism in pregnant women with low free thyroxine (FT₄) levels are limited and inconclusive. Furthermore, the association between maternal FT₄ deficiency and adverse lipid metabolic parameters is unknown. Therefore, we aimed to investigate this association and the effects of levothyroxine (L-T₄) treatment on these metabolic indicators.

METHODS

This retrospective study included 164 patients with isolated hypothyroidism (IH) (FT₄ levels below the 5^th percentile with normal thyroid stimulating hormone levels according to the gestational-specific reference range) and 407 euthyroidism patients (control group who had regular antenatal examinations at Zhejiang Provincial People's Hospital, Hangzhou, China) between January 1, 2019, and December 31, 2020. Patients with IH were divided into levothyroxine (L-treatment group, n = 77) and dietary iodine supplement treatment groups (dietary treatment group, n=87) according to the hospital's treatment policy and clinical experience. The intervention lasted for at least 8 weeks. Metabolic indicators, including thyroid function and lipid parameters, were collected at least twice before and after the intervention. Other data collected included maternal age, history of abortion, prepregnancy BMI, and gestational weight gain (Fig. 1).

RESULTS

Compared with the control group, Patients with IH had a higher degree of dyslipidemia, reflected in elevated total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and apolipoprotein B (Apo B) levels. In IH patients, an inverse correlation was found between FT₄ and TG levels, which remained after adjusting for prepregnancy BMI. The L-treatment group demonstrated a significantly slower rate of hypercholesterolemia progression during pregnancy than the dietary treatment group. In addition, there was a relationship between the therapeutic effect and the degree of disease, with the main factors being FT₄, TSH and TG levels prior to starting treatment.

CONCLUSIONS

Low FT₄ levels were associated with elevated blood lipid levels. Serum FT₄ and lipid levels in patients could be improved by medical intervention.

Exploring associations of anthropometric parameters and serum triglycerides with serum thyroid hormones in young women

Establishing links between serum thyroid hormone panel and triglyceride (TG) concentrations with non-invasively obtained measurements of anthropometric parameters of young women may provide preliminary knowledge about the homeostasis of metabolic processes and body composition and about the strategic role of the tested parameters as early screening tests for assessing the health status of apparently healthy women in the period preceding pregnancy. The study was conducted in 381 healthy female students (aged 18-26 years, mean ± SD = 22.1 ± 1.3). Anthropometric indices (BMI, waist-to-hip ratio, FAT%) were calculated and serum concentrations of thyroid hormones (TSH, fT3, fT4) were determined using electrochemiluminescence immunoassays and serum triglycerides (TG) with a commercially available test. No association was established between serum TSH and anthropometric indices in healthy young women. Increased serum concentrations of fT4, fT3 and TG were found in overweight subjects, i.e. BMI > 24.9 kg/m² (p < 0.05). A significant negative association between fT3 and TG was found in underweight subjects (r = - 0.258, p = 0.049) and a significantly positive association in normal-weight subjects (r = 0.139, p = 0.019). In healthy young women differences in BMI are not related to thyroid function. The opposite directions between the associations fT3 vs TG in underweight compared to normal-weight young prepregnant females may suggest dependencies of fT3 and TG in the regulation of specific BMI-dependent metabolic processes.

Thyrotropin and body mass index, are they related?

OBJECTIVES

It is well recognized that overt thyroid dysfunction is associated with changes in body mass index (BMI). However, there is ongoing debate regarding the influence of thyroid stimulating hormone (TSH) on BMI, in euthyroid subjects. The aim of this study is to examine the association of TSH with BMI in an outpatient population without evidence of thyroid disease.

METHODS

Cross-sectional study conducted in an Endocrinology Department. We identified the latest TSH and BMI measurements in 923 patients from the reference euthyroid population. All patients with positive thyroid autoimmunity and nodules were excluded. We performed a linear regression analysis using SPSSv.025.

RESULTS

923 adult patients were evaluated. 79.4% were males, with a mean age of 67.6 years old. Mean TSH level was 1.78 mIU/L and mean BMI was 29.2 kg/m². A significant negative correlation between serum TSH concentration and BMI was evident (p=0.04; r=-0.067). Statistical significance was lost when performing subgroup analysis, for males and females (p=0.19 and p=0.075), elderly (≥65 years) and non-elderly (p=0.55 and p=0.32) and also obese (BMI ≥30 kg/m²) and non-obese (p=0.39 and p=0.13).

CONCLUSIONS

The relationship between BMI and TSH is not consensual in the literature. This study included a large cohort sample of euthyroid patients, majority men and with negative autoimmunity. Our results support the hypothesis that variation in thyroid status within the normal range, could have a negative effect on BMI, contrary to most published studies.

Mediation effects of thyroid function in the associations between phthalate exposure and lipid metabolism in adults

Phthalates are a group of industrial chemicals widely used in everyday products including cosmetics, food packaging and containers, plastics, and building materials. Previous studies have indicated that urinary phthalate metabolites are associated with metabolic effects including those on lipid metabolism, but the results are mixed. Furthermore, whether thyroid function mediates the association between phthalate exposure and lipid metabolism remains unclear. In the present study, we explored whether changes in thyroid function markers mediate the associations between phthalate exposure and lipid metabolism indicators in Taiwanese adults. The cross-sectional data were obtained from the Taiwan Environmental Survey for Toxicants conducted in 2013. Levels of 11 urinary phthalate metabolites, levels of 5 thyroid hormones, and 8 indicators of lipid metabolism were assessed in 222 Taiwanese adults. The relationships of urinary phthalate metabolite levels with serum thyroid hormone levels and lipid metabolism indicators were explored using multiple regression models. Mediation analysis was conducted to evaluate the role of thyroid function in the association between phthalate exposure and lipid metabolism. The metabolite of di(- 2-ethylhexyl) phthalate (∑DEHPm) exhibited a significant positive association with the lipid metabolite indicator of high-density lipoprotein cholesterol (HDL-C; β = 0.059, 95% confidence interval [CI] = 0.009, 0.109) in adults, and the thyroid function indicator thyroxine (T₄) had a significant negative association with the metabolite ∑DEHPm (β = - 0.059, 95% CI = - 0.101, - 0.016) and a significant negative association with HDL-C (β = - 0.284, 95% CI = - 0.440, - 0.128). The T₄ indirect effect was 0.015 (95% CI = - 0.0087, 0.05), and the mediation effect was 32.2%. Our results support the assumption that exposure to phthalates influences the homeostasis of lipid metabolism by interfering with thyroid function.

Associations among FT4 level, FT3/FT4 ratio, and non-alcoholic fatty liver disease in Chinese patients with hypopituitarism

Non-alcoholic fatty liver disease (NAFLD) is the most common hepatic metabolic disorder. Thyroid function is associated with NAFLD in different populations; however, little attention has been paid in patients with hypopituitarism. To analyze the association between thyroid function and NAFLD, we included 134 patients with hypopituitarism admitted to the Tianjin Medical University General Hospital between June 2013 and May 2019. Participants were divided into the NAFLD(-) and NAFLD(+) groups based on abdominal ultrasonography findings. We evaluated 68 male and 66 female patients with hypopituitarism. The prevalence of NAFLD was 52.24%. The NAFLD(+) group had a significantly higher free triiodothyronine/free thyroxine (FT₃/FT₄) ratio than the NAFLD(-) group (p = 0.003). The NAFLD(+) group showed significantly lower levels of FT₄ and the growth hormone (GH) than the NAFLD(-) group (p = 0.003 and 0.016, respectively). We observed an association of the FT₄ level and FT₃/FT₄ ratio with NAFLD in the univariate model, which was non-significant after adjustment for metabolic parameters (BMI, HDL-C, triglycerides, serum uric acid, blood pressure, fasting glucose). To better understand the role of each metabolic parameters, we performed additional models for each of those predictors individually after adjustment for age and gender, the association between FT₄ level and FT₃/FT₄ ratio lost significance after adjustment for HDL-C and TG, but not for other predictors. Our findings suggest that thyroid dysfunction may be crucially involved in NAFLD by regulating whole-body metabolism, especially lipid utilization. Therefore, sufficient thyroid hormone replacement therapy for patients with hypopituitarism is recommended from the early stage.

Subclinical Hypothyroidism in Families Due to Chronic Consumption of Nitrate-Contaminated Water in Rural Areas with Intensive Livestock and Agricultural Practices in Durango, Mexico

Nitrate is a widely disseminated water pollutant and has been linked to health disorders, including hypothyroidism. Here, we evaluated the relationship between thyroid function and chronic exposure to nitrates in rural zone families, in addition to the genetic and autoimmune factors. Exposure and effect biomarkers, thyroid hormones, and autoantibodies of tiroperoxidase were measured, as well the presence of two FOXE1 polymorphisms (rs965513, rs1867277). Pearson’s correlation, principal component analysis, Kruskal–Wallis, and chi-squared tests were used for statistical analysis. A total of 102 individuals were analyzed; 45% presented subclinical hypothyroidism, a negative correlation was observed between methemoglobin and the total T3 (r = −0.43, p = 0.001) and free T3 levels (r = −0.34, p = 0.001), as well as between TSH and the free T4 (r = −0.41, p = 0.0001) and total T4 (r = −0.36, p = 0.0001). A total of 15.7% had positive antithyroid ab-TPO, while the polymorphic genotype (AA) represented only 3% (rs965513) and 4% (rs1867277) among subjects with subclinical hypothyroidism. The high frequency of subclinical hypothyroidism in the population under study could be related, mainly, to chronic exposure through the consumption of nitrate-contaminated water.

Thyroid-stimulating hormone levels in euthyroid patients 8 years following bariatric surgery

Background

Bariatric surgery (BS) was shown to promote a decline in thyroid-stimulating hormone (TSH) in euthyroid patients with severe obesity in the short-term. Aim of the present study was to assess the effect of weight loss on thyroid function in euthyroid patients in the long-term following different bariatric procedures.

Methods

In a retrospective cohort study including 135 patients at baseline, thyroid function was assessed at six time points up to 8 years after surgery. Patients were stratified by TSH levels at baseline and divided into two groups to compare the change in TSH at long-time. We used log-linear regression to assess the relation between thyroid hormones and TSH and linear regression analyses to identify variables that were thought to determine TSH and fT3/fT4-ratio as well as their change long-term.

Results

Over a mean follow-up of 8 years, TSH and fT3/fT4-ratio declined (both p < 0.001). Patients with high-normal TSH showed a greater decline in TSH than those with normal TSH compared to baseline. Thyroid hormones and TSH displayed a negative log-linear correlation at long-term follow-up. Change in TSH at long-time showed a negative correlation with TSH at baseline (B = −0.55; p < 0.001). With regard to type of surgery, there were no significant differences in TSH.

Conclusion

BS promotes a decline of TSH in euthyroid patients up to 8 years after intervention despite weight regain. The greatest change in TSH was seen among patients with high-normal baseline-TSH. Results of log-linear regression suggest recovery of the pituitary-thyroid axis. Type of surgery did not affect the change in TSH levels over time.

FT3/FT4 mediated the effect of pre-pregnancy body mass index or maternal weight gain during early pregnancy on gestational diabetes mellitus

OBJECTIVE

Maternal overweight or obesity during early pregnancy could increase the subsequent risk of gestational diabetes mellitus (GDM). However, whether these associations were mediated by thyroid hormones and their effect sizes were still unknown. This study aimed to identify the mediating effects of thyroid parameters between pre-pregnancy body mass index (BMI)/maternal weight gain during early pregnancy with subsequent risk of GDM.

METHODS

This prospective mother-infant cohort study was conducted from 2018 to 2019. A total of 2,772 singleton pregnant women were included for analysis. Questionnaire survey, anthropometric measures, and thyroid function testing were conducted in early pregnancy. Deiodinase activity was evaluated using free-triiodothyronine-to-free-thyroxine ratio (FT3/FT4). A standard 75 g oral glucose tolerance test was performed during 24-28 weeks of gestation to diagnose GDM. Mediation analysis was performed on PROCESS 3.5 to examine the mediating effects of thyroid parameters between pre-pregnancy BMI/maternal weight gain during early pregnancy and the subsequent GDM risk.

RESULTS

FT3/FT4 ratio was a significant mediator between pre-pregnancy BMI or maternal weight gain and GDM, accounting for 16.5% and 18.6% of total effects, respectively. FT3 also mediated the association of pre-pregnancy BMI with GDM, accounting for 3.3% of total effects. Thyroid-stimulating hormone suppressed the effects of pre-pregnancy BMI and maternal weight gain on GDM risk, and the proportions of total effects were 2.4% and 6.4%, respectively.

CONCLUSIONS

Deiodinase activity, as indicated by FT3/FT4 ratio, was the strongest mediator among thyroid parameters between pre-pregnancy BMI/maternal early weight gain and GDM.

Optimized Replacement T4 and T4+T3 Dosing in Male and Female Hypothyroid Patients With Different BMIs Using a Personalized Mechanistic Model of Thyroid Hormone Regulation Dynamics

OBJECTIVE

A personalized simulation tool, p-THYROSIM, was developed (1) to better optimize replacement LT4 and LT4+LT3 dosing for hypothyroid patients, based on individual hormone levels, BMIs, and gender; and (2) to better understand how gender and BMI impact thyroid dynamical regulation over time in these patients.

METHODS

p-THYROSIM was developed by (1) modifying and refining THYROSIM, an established physiologically based mechanistic model of the system regulating serum T3, T4, and TSH level dynamics; (2) incorporating sex and BMI of individual patients into the model; and (3) quantifying it with 3 experimental datasets and validating it with a fourth containing data from distinct male and female patients across a wide range of BMIs. For validation, we compared our optimized predictions with previously published results on optimized LT4 monotherapies. We also optimized combination T3+T4 dosing and computed unmeasured residual thyroid function (RTF) across a wide range of BMIs from male and female patient data.

RESULTS

Compared with 3 other dosing methods, the accuracy of p-THYROSIM optimized dosages for LT4 monotherapy was better overall (53% vs. 44%, 43%, and 38%) and for extreme BMI patients (63% vs. ~51% low BMI, 48% vs. ~36% and 22% for high BMI). Optimal dosing for combination LT4+LT3 therapy and unmeasured RTFs was predictively computed with p-THYROSIM for male and female patients in low, normal, and high BMI ranges, yielding daily T3 doses of 5 to 7.5 μg of LT3 combined with 62.5-100 μg of LT4 for women or 75-125 μg of LT4 for men. Also, graphs of steady-state serum T3, T4, and TSH concentrations vs. RTF (range 0%-50%) for untreated patients showed that neither BMI nor gender had any effect on RTF predictions for our patient cohort data. Notably, the graphs provide a means for estimating unmeasurable RTFs for individual patients from their hormone measurements before treatment.

CONCLUSIONS

p-THYROSIM can provide accurate monotherapies for male and female hypothyroid patients, personalized with their BMIs. Where combination therapy is warranted, our results predict that not much LT3 is needed in addition to LT4 to restore euthyroid levels, suggesting opportunities for further research exploring combination therapy with lower T3 doses and slow-releasing T3 formulations.

Is eNAMPT/visfatin a potential serum marker of papillary thyroid cancer?

PURPOSE

The role of nicotinamide phosphoribosyltransferase (NAMPT)/visfatin in a more aggressive course of many malignancies has been proven. Previous studies have noticed the importance of visfatin in thyroid neoplastic tissue, but the diagnostic and prognostic value of its serum concentration has not been investigated so far. Our study aimed to consider whether extracellular NAMPT (eNAMPT) could be a potential serum marker in recurrent papillary thyroid cancer (PTC).

METHODS

It was a prospective observational study with consecutive enrolment. We recruited 100 patients with PTC after thyroidectomy with postoperative ¹³¹I ablation and 100 healthy controls. Also, 50 randomly selected patients underwent laboratory assessment (including eNAMPT serum concentration by ELISA Assay Kit, TSH, free thyroid hormones, TSH-stimulated thyroglobulin Tg, antibodies - TgAbs, TPOAb) and body composition analysis twice: at admission and 6 months after being on suppressive levothyroxine doses. TSH-stimulated Tg of 1 ng/ml was defined as the cutoff value for predicting disease status as complete remission (n = 55) and recurrent or persistent structural disease (n = 45).

RESULTS

The visfatin serum concentrations in patients diagnosed with PTC and in healthy subjects were not statistically significantly different (p = 0.9425). The eNAMPT levels were also similar in disease-free patients and the ones with tumour relapse. Besides, ROC curve analysis did not detect eNAMPT as a biomarker of PTC.

CONCLUSION

We have not found visfatin as a potential serum marker of papillary thyroid cancer. Also, eNAMPT has no prognostic value in assessing the risk of disease recurrence or metastasis in PTC management.

Mediating effect analysis of visceral adiposity index on free triiodothyronine to free thyroxine ratio and non-alcoholic fatty liver disease in euthyroid population

BACKGROUND

The association between free triiodothyronine/free thyroxine (FT3/FT4) and non-alcoholic fatty liver disease (NAFLD) in euthyroid subjects is unclear. In addition, few studies have explored whether VAI mediates the association between FT3/FT4 ratio and NAFLD in the euthyroid population. We aimed to analyze the mediating effect of VAI on the FT3/FT4 ratio and NAFLD risk in the euthyroid population.

METHODS

This cross-sectional study included 7 946 annual health examinees from the Health Examination Center, Hebei General Hospital, from January to December 2020. The basic information and biochemical parameters, as well as calculated FT3/FT4 ratio and VAI were collected. NAFLD was diagnosed according to abdominal ultrasonography. The fibrosis score for NAFLD positive subjects (NFS) was calculated to reflect the extent of liver fibrosis. The risk of NAFLD was analyzed by quartiles of FT3/FT4 ratio (Q1-Q4 quartiles) and VAI (V1-V4 quartiles), respectively. Pearson correlation analysis was performed to investigate the correlation between FT3/FT4 ratio and VAI. Multivariate logistic regression analysis was applied to analyze the effect of FT3/FT4 ratio and VAI on NAFLD and NFS status. Bootstrap was conducted to explore whether VAI mediated the association between FT3/FT4 ratio and NAFLD.

RESULTS

Of the 7 946 participants, 2 810 (35.36%) had NAFLD and 5 136 (64.64%) did not. Pearson correlation analysis indicated that FT3/FT4 ratio was positively associated with VAI (P<0.05). Multivariate logistic regression analysis indicated that compared to the Q1 group, the risk of NAFLD significantly increased in Q3 group [OR=1.255, 95%CI (1.011, 1.559)] and Q4 group [OR=1.553, 95%CI (1.252, 1.926)](P<0.05). Compared to the V1 group, the risk of NAFLD notably increased in V2 group [OR=1.584, 95%CI (1.205, 2.083)], V3 group [OR=2.386, 95%CI (1.778, 3.202)] and V4 group [OR=4.104, 95%CI (2.835, 5.939)] (P<0.01). There was no relevance between FT3/FT4 ratio, VAI and NFS status. Mediating effect analysis showed that FT3/FT4 ratio significantly directly influenced NAFLD prevalence [β=3.7029, 95%CI (2.9583, 4.4474)], and VAI partly mediated the indirect effect of the FT3/FT4 ratio on NAFLD prevalence [β=2.7649, 95%CI (2.2347, 3.3466)], and the mediating effect accounted for 42.75% of the total effects.

CONCLUSION

Both FT3/FT4 ratio and VAI were predictors of NAFLD, and VAI partly mediated the indirect effect of the FT3/FT4 ratio on NAFLD prevalence in the euthyroid population.

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.

Association between thyroid hormone and components of metabolic syndrome in euthyroid Korean adults: A population-based study

Thyroid dysfunction increases the prevalence of metabolic syndrome. However, the link between thyroid hormones and metabolic syndrome remains debatable, and the effect of sex on their relationship is not completely understood. To elucidate the relationship of thyroid hormones with metabolic syndrome and its components according to sex in euthyroid individuals in South Korea. Adult participants who underwent thyroid tests at our institution between January 2015 and December 2018 and had thyroid-stimulating hormone (TSH; 0.270-4.200 μIU/mL) and free thyroxine (FT4; 0.93-1.70 ng/dL) levels in the normal range were included. After correcting for age and body mass index, multiple linear regression was performed to assess the association of TSH and FT4 with metabolic syndrome and its components, and logistic regression was performed to estimate the risk of developing metabolic syndrome and its components according to different thyroid hormone quartiles. We included 12,478 men and 7,575 women in this study. The prevalence of metabolic syndrome was 9.68%. In men, TSH was positively associated with blood pressure and triglycerides, and the odds ratio for high blood pressure and hypertriglyceridemia was approximately 1.3 times higher in the fourth quartile than in the first quartile. FT4 associated positively with waist circumference, and a high odds ratio for abdominal obesity in the fourth quartile was observed in both men (odds ratio [OR], 1.239; 95% confidence interval [CI], 1.045-1.470) and women (OR, 1.302; 95% CI, 1.029-1.649). A negative association was found between FT4 and triglycerides, and concurrently, the odds ratios for hypertriglyceridemia were lower in the fourth quartile in both men (OR, 0.692; 95% CI, 0.619-0.774) and women (OR: 0.641; 95% CI: 0.512-0.803). In addition, a higher odds ratio for high blood pressure was observed in the fourth quartiles of FT4 and TSH in women. However, there was no association between TSH and FT4 levels and the onset of metabolic syndrome in either of the sexes. Serum TSH and FT4 levels were associated with different metabolic syndrome components in men and women, but there was no association with the onset of metabolic syndrome.

Associations between the thyroid panel and serum protein concentrations across pregnancy

Establishing any characteristic associations between the serum parameters of thyroid function and serum proteins in pregnancy may aid in elucidating the role of the thyroid gland in the regulation of pregnancy-specific metabolic processes and in selecting candidate biomarkers for use in their clinical assessment. Concentrations of thyroid stimulating hormone (TSH), free tri-iodothyronine (fT3) and free thyroxine (fT4), six electrophoretically separated protein fractions (albumin, alpha-1-, alpha2-, beta-1-, beta-2- and gamma-globulins), representative proteins—albumin (ALB), transferrin (TRF), alpha-2-macroglobulin (AMG) and ceruloplasmin (CER) were measured in 136 serum samples from 65 women in their consecutive trimesters of pregnancy. The concentrations of TSH, fT4 and fT3 were significantly correlated (p < 0.05) with the concentrations of the albumin, alpha-2- and beta-1 globulin fractions. Significant correlations (p < 0.05) which were positive between fT4 and ALB and negative between fT4 and TRF were established throughout pregnancy. Significant negative correlations (p < 0.05) were demonstrated for fT3 with alpha-2-globulin, AMG and CER. Changes in the serum concentrations of thyroid hormones seen between the trimesters were found to correlate with the concentrations of high-abundance serum proteins. Opposite directions of correlations between fT4 and ALB and fT4 and TRF observed throughout pregnancy may indicate the shared biological role of these parameters in maintaining maternal homeostasis and they suggest their potential use in the clinic as a simple biomarker panel. A negative correlation of fT3 with CER in the second trimester possibly reflects their involvement in the active regulation of metabolic processes.

Environmental Factors Affecting Thyroid-Stimulating Hormone and Thyroid Hormone Levels

Thyroid hormones are necessary for the normal functioning of physiological systems. Therefore, knowledge of any factor (whether genetic, environmental or intrinsic) that alters the levels of thyroid-stimulating hormone (TSH) and thyroid hormones is crucial. Genetic factors contribute up to 65% of interindividual variations in TSH and thyroid hormone levels, but many environmental factors can also affect thyroid function. This review discusses studies that have analyzed the impact of environmental factors on TSH and thyroid hormone levels in healthy adults. We included lifestyle factors (smoking, alcohol consumption, diet and exercise) and pollutants (chemicals and heavy metals). Many inconsistencies in the results have been observed between studies, making it difficult to draw a general conclusion about how a particular environmental factor influences TSH and thyroid hormone levels. However, lifestyle factors that showed the clearest association with TSH and thyroid hormones were smoking, body mass index (BMI) and iodine (micronutrient taken from the diet). Smoking mainly led to a decrease in TSH levels and an increase in triiodothyronine (T3) and thyroxine (T4) levels, while BMI levels were positively correlated with TSH and free T3 levels. Excess iodine led to an increase in TSH levels and a decrease in thyroid hormone levels. Among the pollutants analyzed, most studies observed a decrease in thyroid hormone levels after exposure to perchlorate. Future studies should continue to analyze the impact of environmental factors on thyroid function as they could contribute to understanding the complex background of gene-environment interactions underlying the pathology of thyroid diseases.

Mediation effects of thyroid function in the associations between phthalate exposure and glucose metabolism in adults

The mediating influence of thyroid function on the association of phthalate exposure with glucose metabolism, including insulin resistance, remains unclear. We explored the mediating influence of thyroid hormone levels on the phthalate exposure-insulin resistance association. This cross-sectional study of 217 Taiwanese adults assessed insulin resistance (Homeostatic Model Assessment for Insulin Resistance, HOMA-IR scores) and the levels of 11 urinary phthalate metabolites and 5 thyroid hormones. Multiple regression models were used to analyze the associations among serum thyroid hormone levels, urinary phthalate metabolite levels, and HOMA-IR scores. The mediation analysis assessed the influence of thyroid function on the phthalate exposure-HOMA-IR association. Our data indicated urinary mono-ethylhexyl phthalate (MEHP) levels was negatively associated with free thyroxine (T₄) (β = -0.018; 95% confidence interval [CI]: -0.031, -0.005) and positively associated with HOMA-IR scores (β = 0.051, 95% CI: 0.012, 0.090). The study also revealed urinary mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) levels was negatively associated with free T₄ (β = -0.036, 95% CI: -0.056, -0.017) and HOMA-IR (β = 0.070, 95% CI: 0.013, 0.126). Free T₄ and HOMA-IR had a negative association (β = -0.757, 95% CI: -1.122, -0.392). In the mediation analysis, free T₄ mediated 24% and 35% of the associations of urinary MEHP and MEOHP with HOMA-IR, respectively. Our findings revealed the mediating role of thyroid function in the phthalate exposure-glucose metabolism association in adults.

Prevalence and risk factors of overweight and obesity in Chinese patients with first-episode drug-naïve major depressive disorder

BACKGROUNDS

Obesity and overweight are common in patients with major depressive disorder (MDD); the results are inconsistent due to confounding variables involved in studies. Furthermore, no well-designed study has been published to investigate the prevalence, risk factors and underlying mechanisms of obesity/overweight in Chinese MDD patients. This study aimed to investigate the prevalence of obesity/overweight and related risk factors in first-episode, drug-naïve (FEDN) patients with MDD in China.

METHODS

A total of 1718 patients were recruited. Their clinical and anthropometric data, thyroid function and biochemical parameters were collected. All patients were evaluated on the 17-item Hamilton Rating Scale for Depression, 14-item Hamilton Anxiety Rating Scale and the Positive and Negative Syndrome Scale.

RESULTS

The prevalence of obesity and overweight was 3.73% and 56.00%, respectively. Multivariable logistic regression analysis showed that TSH was the only independent risk factor for weight gain in MDD patents. The fitting curve of the relationship between TSH and BMI formed an inverted U-shaped parabola. The ordinal logit mode showed that when TSH<=2.68 was set as a reference, the odd rates of weight increased with the increase of TSH, and the highest rate was 3.929 (95%CI: 2.879-5.361, P<0.0001).

LIMITATION

Causality cannot be drawn due to cross-sectional design.

CONCLUSION

Our results suggest that overweight is very common among patients with FEDN MDD rather than obesity. TSH is a promising predictor and potential biomarker of high weight in MDD patients, and there is an inverted U-shaped parabolic relationship between TSH and BMI.

Application of Proteomics and Metabonomics to Reveal the Molecular Basis of Atractylodis Macrocephalae Rhizome for Ameliorating Hypothyroidism Instead of Hyperthyroidism

As the treatments of diseases with Chinese herbs are holistic and characterized by multiple components, pathways, and targets, elucidating the efficacy of Chinese herbs in treating diseases, and their molecular basis, requires a comprehensive, network-based approach. In this study, we used a network pharmacology strategy, as well as in vivo proteomics and metabonomics, to reveal the molecular basis by which Atractylodis macrocephalae rhizome (AMR) ameliorates hypothyroidism. Eighteen main compounds from AMR and its fractions (volatile oil fraction, crude polysaccharides fraction, lactones fraction, oligosaccharide fraction, and atractyloside fraction) were identified by HPLC, and their targets were screened using the TCMSP database and Swiss Target Prediction. Disease targets were gathered from the TTD, CTD and TCMSP databases. Hub targets were screened by different plug-ins, such as Bisogene, Merge, and CytoNCA, in Cytoscape 3.7.1 software and analyzed for pathways by the DAVID database. Hypothyroidism and hyperthyroidism pharmacological models were established through systems pharmacology based on proteomic and metabolomic techniques. Finally, AMR and its fractions were able to ameliorate the hypothyroidism model to different degrees, whereas no significant improvements were noted in the hyperthyroidism model. The lactones fraction and the crude polysaccharides fraction were considered the most important components of AMR for ameliorating hypothyroidism. These amelioration effects were achieved through promoting substance and energy metabolism. In sum, the integrative approach used in this study demonstrates how network pharmacology, proteomics, and metabolomics can be used effectively to elucidate the efficacy, molecular basis, and mechanism of action of medicines used in TCM.

The Role of Sleep Curtailment on Leptin Levels in Obesity and Diabetes Mellitus

Emerging evidence has identified sleep as a significant, but modifiable, risk factor for metabolic syndrome, diabetes, and obesity. Leptin, an adipocyte-derived peptide and a regulator of food intake and energy expenditure, has been shown to be associated with a short sleep duration in the pathophysiology of obesity and consequently type 2 diabetes. This review focuses on the current evidence indicating the effects of a short sleep duration on the regulation of leptin concentration in association with obesity and diabetes mellitus. In summary, the evidence suggests that sleep deprivation, by affecting leptin regulation, may lead to obesity and consequently development of type 2 diabetes through increased appetite and food intake. However, findings on the role of leptin in diabetes due to sleep deprivation are contradictory, and further studies with larger sample sizes are needed to confirm previous findings.

Association Between Body Mass Index and Thyroid Function in Euthyroid Chinese Adults

BACKGROUND Obesity can influence thyroid function through multiple routes, even in people who are euthyroid. The correlation between weight and thyroid function is a matter of debate. The present study investigated the relationship between body weight and thyroid function in euthyroid Chinese adults. MATERIAL AND METHODS A total of 1564 participants with serum thyrotropin (TSH) and thyroid hormone levels within the reference range were included. All of them were tested for thyroid function parameters and categorized, based on body mass index (BMI), into 3 groups: normal weight, overweight, and obese. The effects of BMI on thyroid function were examined using linear (continuous values) and logistic (dichotomous levels according to medians or means) regression and controlling for age and sex. RESULTS There were significant differences in free triiodothyronine (FT3) levels and FT3/free thyroxine (FT4) ratios among participants who were normal weight, overweight, and obese (both P<0.001). Multivariable regression analysis (P<0.001) showed that BMI was positively associated with FT3 levels and FT3/FT4 ratios. Compared with the normal weight group, the patients who were overweight or obese had significantly higher FT3 levels and FT3/FT4 ratios that were higher than average, according to logistic regression analyses. CONCLUSIONS We found that Chinese adults who are obese may have higher FT3 levels and FT3/FT4 ratios than those who are of normal weight, even if their thyroid function values are within the normal range.

The Influence of Reducing Diets on Changes in Thyroid Parameters in Women Suffering from Obesity and Hashimoto's Disease

Hashimoto’s disease is listed among the most common endocrine causes of obesity. As treatment of obesity in women with Hashimoto’s disease is frequently unsuccessful, the aim of this study was to evaluate the effectiveness of two different reducing diets and their influence on changes in thyroid parameters in female patients. A six-month observational/interventional study was performed on 100 women aged 18–65 years, previously diagnosed with Hashimoto’s disease and obesity and receiving L-thyroxine. The women were randomly assigned to the test group (group A, n = 50) following elimination/reducing diets, and the control group (group B, n = 50) following reducing diets with the same caloric content (without elimination). Anthropometric and thyroid parameters were evaluated at the beginning, after 3 months and after 6 months of treatment. In both groups a significant decrease in BMI and body fat percentage was achieved, but in test group A the decrease in BMI and body fat percentage was significantly greater than in control group B (p < 0.002 and p = 0.026, respectively). Serum TSH (thyroid stimulating hormon) levels decreased significantly more in group A than in group B (p < 0.001). Group A exhibited significantly greater increases in fT4 and fT3 levels than the control group (p < 0.001) as well as significantly greater decreases in the levels anti-TPO (thyroid peroxidase) (p < 0.001) and anti-TG (thyreoglobulin) antibodies (p = 0.048). The application of reducing diets with product elimination was found to be a more beneficial tool for changing anthropometric and thyroid parameters in women suffering from obesity and Hashimoto’s disease than classic reducing diets with the same energy values and macronutrient content.

Association of thyroid hormones with blood pressure and arterial stiffness in the general population: The Dali study

Thyroid dysfunction plays a role in blood pressure (BP) regulation. However, the associations between thyroid function and BP and arterial stiffness in the general Chinese population without thyroid disease are unknown. This population-based cross-sectional study aimed to investigate the association between thyroid function and peripheral and central BP and arterial stiffness in Chinese individuals. After excluding those who had thyroid diseases or incomplete clinical measurements, this study included 691 participants. Of the participants, 444 (64.2%) were women and 215 (31.1%) had hypertension. After adjustment for covariates, serum FT3 was significantly associated with a higher pulse rate in both sexes. In men, each 2.72-fold increase in serum FT4 levels was associated with higher peripheral systolic BP (+10.82 mmHg, p = .005) and pulse pressure (+5.71 mmHg, p = .03). Each 2.72-fold increase in serum FT4 levels was associated with higher central systolic BP (+8.03 mmHg, p = .03) and pulse pressure (+3.89 mmHg, p = .05). In women, serum FT4 was only associated with a higher central pulse pressure (+2.96 mmHg, p = .04). After adjustment for covariates, serum FT4 was significantly associated with a faster cfPWV exclusively in men. Our study showed that serum FT4 is associated with higher peripheral and central BP and faster cfPWV in men, whereas serum FT3 is positively associated with a higher pulse rate in both sexes, indicating that the effects of thyroid function on BP and arterial stiffness are more significant in men than in women.

A case-control study on the association of mineral elements exposure and thyroid tumor and goiter

Thyroid tumor and thyroid goiter are prevalent disease around the world. In this case-control study, we investigated the association between exposure to a total of twelve mineral elements and thyroid disease as well as thyroid functions. Participants with thyroid tumor or goiter (N = 197) were matched with a healthy population (N = 197) by age (± 2 years old) and same sex. Questionnaires were used to collect data about the demographic characteristics and information of subjects. Serum and urine samples were collected simultaneously for each of the subjects. Mineral elements, iodine level of urine and levels of the total seven thyroid function indexes in serum were detected respectively. Conditional logistic regression was applied to estimate the associations between mineral elements and the risk of thyroid tumor and goiter through single-element models and multiple-element models. Multiple linear regression was used to evaluate relationships between mineral elements and percentage changes of thyroid functions. Higher concentrations of mineral elements in the recruited population were found in this study than other comparable studies, and the levels of chromium (Cr), manganese (Mn), nickel (Ni), arsenic (As), cadmium (Cd), selenium (Se), antimony (Sb), thallium (Tl) and lead (Pb) in the case group were lower than the control group. According to the single-element models, Cr, Mn, Ni, Sb and Tl showed significant negative associations with the risk of thyroid tumor and goiter, and, Cd showed nonmonotonic dose response. Cd and mercury (Hg) showed a nonmonotonic percentage change with T4, while Tl was associated with the increased FT4 in the control group. Therefore, Cd, Hg and Tl may disturb the balance of thyroid function to some extent, and Cr, Mn, Ni, Cd, Sb, and Tl may become potential influencing factors for the risk of thyroid tumor and goiter.

Correlations between neck circumference and serum thyroid hormones levels in postmenopausal women with euthyroid and subclinical hypothyroidism

Middle-aged and elderly women are at a higher risk of subclinical hypothyroidism (SHypo). Menopause is an important period of metabolic change in women and thyroid hormones are closely related to metabolic status. Neck circumference (NC) is a simple anthropometric index that reflects upper body fat accumulation. Therefore, this study aimed to explore the relationship between NC and thyroid hormones in postmenopausal women. A total of 1050 postmenopausal women were enrolled from Shanghai Zhabei communities (888 euthyroid subjects and 162 SHypo patients). Anthropometric parameters, including NC, were measured. The measurements of serum thyroid hormones were performed by electrochemical luminescence immunoassay. The results showed NC was positively correlated with thyroid-stimulating hormone (TSH) (r = .064, P = .039). TSH and the proportion of SHypo patients increased significantly in those with elevated NC (both P < .05). In logistic regression analysis, the risk of SHypo increased by 46.4% in those with elevated NC (OR = 1.464 [1.035-2.071], P = .031). After adjusting for metabolic confounding factors, the positive association disappeared (P = .112). Multiple linear regression analysis showed there were no significant correlations between NC and TSH in either univariate or multivariate model in the total population (both P > .05). And in the subgroup analysis of euthyroid and SHypo individuals, NC was also not related to TSH (all P > .05). In conclusion, there was no independent association between NC, a simple anthropometric index for upper body fat accumulation, and serum TSH levels in Chinese euthyroid and SHypo postmenopausal women.

Selenium status and its relationship with thyroid hormones in obese women

BACKGROUND AND AIMS

Studies have been conducted with the purpose of elucidating thyroid gland dysfunction in obesity, however the contributing factors for such dysfunction are not yet fully understood. Selenium is notable for its role in thyrocyte protection against oxidative damage and control of thyroid hormone synthesis. In addition, subjects with obesity may exhibit alterations in the selenium homeostasis. Therefore, the present study aimed to examine the selenium status and its relationship with serum thyroid hormone levels in obese women.

METHODS

This cross-sectional study included 69 euthyroid women, aged between 18 and 50 years, who were divided in two groups: an obese group (n = 35) and a control group with women of normal weight (n = 34). Selenium intake was assessed by three-day diet records and analyzed using NutWin software version 1.5. Plasma, erythrocyte, and urinary selenium levels were determined using inductively coupled plasma optical emission spectrometry. Testing for thyroid hormones and thyroid autoantibodies was performed based on chemiluminescence.

RESULTS

The median dietary selenium content was adequate according to the recommendations, with no statistical difference between groups. Obese women had reduced plasma and erythrocyte selenium levels compared to the control group, although selenium concentration in erythrocytes was adequate within the normal range for both groups. There was no significant difference between the urinary selenium concentrations in the subjects; however, the mineral clearance was higher in the obese group. Free triiodothyronine (fT3) and free thyroxine (fT4) levels were higher in obese women with class II obesity when compared to the control group. There was a negative correlation between plasma selenium and serum fT4 levels.

CONCLUSIONS

Obese women showed impairment in selenium homeostasis, however, this fact did not seem to adversely affect thyroid metabolism.

Gender- and age-related differences in homocysteine concentration: a cross-sectional study of the general population of China

The primary goals of this study were to evaluate the gender- and age-related differences in homocysteine concentration in the general population of China and possible influencing factors. A total of 7872 subjects, divided into male and female groups, participated in this retrospective study. The average homocysteine level, prevalence of hyperhomocysteinemia, and independent factors affecting homocysteine concentration were analyzed. The homocysteine level was significantly higher in males than in females in each age range (aged 20–30, aged 30–40, aged 40–50, aged 50–60, aged 60–80, aged over 80) (P < 0.0001), and the trend did not abate with age. The homocysteine concentration first decreased and then increased, being lowest at 30–50 years of age and significantly increased after 50 years of age. Factors associated with homocysteine concentration in males were smoking status (current smokers versus ex-smokers: β: 0.112), estimated glomerular filtration rate (β =  − 0.192), blood urea nitrogen (β =  − 0.14), diastolic blood pressure (β =  − 0.113), free triiodothyronine (β =  − 0.091), serum potassium (β =  − 0.107) and cystatin C (β = 0.173). In females, independent factors associated with homocysteine concentration were cystatin C (β = 0.319), albumin (β = 0.227), free thyroxine (β = 0.179), age (β = 0.148), free triiodothyronine (β =  − 0.217) and serum potassium (β =  − 0.153). The homocysteine level was significantly higher in males than in females and increased markedly after 50 years of age in both groups. The independent factors associated with increased homocysteine concentration differed between males and females.

[The activity of NAD- and NAD(P)-dependent dehydrogenases in lymphocytes of peripheral blood in Graves' disease]

BACKGROUND

The regulatory effect of thyroid hormones on the metabolism of the immune system cells (activation of oxidative processes, separation of oxidative phosphorylation and increased protein synthesis) depends on their number. Changes in the activity of intracellular enzymes in Graves&rsquo; disease (GD) can determine the mechanisms of maintaining autoimmune inflammation in relapse of the disease. The exact role of NAD(P)-dependent dehydrogenases in the development and maintenance of immune response in GD is still poorly investigated.

AIMS

To study the activity of NAD(P)-dependent dehydrogenases in lymphocytes of peripheral blood in patients with manifestation and relapse of GD to clarify the mechanisms of development and progression of the autoimmune process.

METHODS

A single-center, cohort, prospective, continuous, observational, open-label, controlled trial was conducted to evaluate the lymphocytes NAD(P)-dependent activity in 151 women with GD and hyperthyroidism, mean age 40.7&plusmn;13.2, 52 (37.14%), who were on follow-up at the endocrinology center of Krasnoyarsk Regional clinical hospital from 2016 to 2019. The NAD(P)-dependent dehydrogenases activity measured using biochemiluminescence method.

RESULTS

In patients with newly diagnosed of GD, relative to the control values and levels detected in relapse group we observe the increase of G6PDH and decrease of NADH-LDH. In GD relapse group compare to the control range in blood lymphocytes decreases the activity of LDH and NAD(P)-ICDH. In patients with newly diagnosed GD, two positive сorrelation were found: between fT3 level and MDG activity (r=0.90, p=0.037), and between fT4 level and NAD(P)-ICDH activity (r=0.82, p=0.007). In patients with relapse of GD positive relationships between the concentration of TSH and the activity of LDH (r=0.73, p=0.039), and MDH (r=0.93, p=0.002), as well as in a pair of fT4 and NADGDH (r=0.70, p=0.036) were revealed.

CONCLUSION

The established differences in the activity of NAD(P)-dependent dehydrogenases in peripheral blood lymphocytes in patients with manifestation and relapse of GD can reflect in the first case the response of immune cells to a functional-regulatory signal with the development of hyperthyroidism, and in the second case, adaptive changes with the progression of autoimmune process.

The role of thyroid hormone in metabolism and metabolic syndrome

Metabolic syndrome (MetS) and thyroid dysfunction are common in clinical practice. The objectives of this review are to discuss some proposed mechanisms by which thyroid dysfunctions may lead to MetS, to describe the bidirectional relationship between thyroid hormones (THs) and adiposity and finally, to resume a list of recent studies in humans that evaluated possible associations between thyroid hormone status and MetS or its clinical components. Not solely THs, but also its metabolites regulate metabolic rate, influencing adiposity. The mechanisms enrolled are related to its direct effect on adenosine triphosphate (ATP) utilization, uncoupling synthesis of ATP, mitochondrial biogenesis, and its inotropic and chronotropic effects. THs also act controlling core body temperature, appetite, and sympathetic activity. In a bidirectional way, thyroid function is affected by adiposity. Leptin is one of the hallmarks, but the pro-inflammatory cytokines and also insulin resistance impact thyroid function and perhaps its structure. MetS development and weight gain have been positively associated with thyroid-stimulating hormone (TSH) in several studies. Adverse glucose metabolism may be related to hyperthyroidism, but also to reduction of thyroid function or higher serum TSH, as do abnormal serum triglyceride levels. Hypo- and hyperthyroidism have been related to higher blood pressure (BP), that may be consequence of genomic or nongenomic action of THs on the vasculature and in the heart. In summary, the interaction between THs and components of MetS is complex and not fully understood. More longitudinal studies controlling each of all confounding variables that interact with endpoints or exposure factors are still necessary.