Serum TSH is positively associated with BMI

Determination of Serum Zinc and Phosphorus Levels in Patients with Hypothyroidism

Various studies reported that serum zinc (Zn) and phosphorus (P) levels altered in patients with hypothyroidism and vice versa, but results were found inconsistent. It was aimed to find the association between serum Zn and P in patients with hypothyroidism. In this case-control study, a total of 100 subjects (50 newly diagnosed patients of hypothyroidism and 50 controls) were enrolled aged between 25 and 60 years. Biochemical parameters such as thyroid profile, serum Zn, and P were estimated in each subject. A p < 0.05 was considered statistically significant. The mean level of body mass index (BMI), thyroid-stimulating hormone (TSH), and serum P was found significantly elevated in cases compared to controls (p < 0.001). However, the mean level of total triiodothyronine (T3), thyroxine (T4), and serum Zn was found significantly reduced in cases compared to controls (p < 0.001). The serum Zn has shown a significant negative correlation with T3 and BMI among cases (r =  - 0.313 p < 0.05, r =  - 0.338 p < 0.05, respectively). However, serum P has shown a significant positive correlation with TSH and BMI among cases (r = 0.310 p < 0.05, r = 0.449 p < 0.01, respectively). Regression analysis indicated that serum Zn significantly predicted hypothyroidism (p < 0.00). Similarly, serum P significantly predicted hypothyroidism (p < 0.007). Results showed that serum Zn levels were significantly reduced and serum P levels were significantly elevated in cases compared to controls. The serum Zn and serum P both significantly associated with hypothyroidism.

Are resting metabolic rate and clinical symptoms affected by variation of serum thyroid stimulating hormone levels within the normal range in healthy and women with hypothyroidism? A case-control study

BACKGROUND

It is unclear whether variation in thyroid stimulating hormone (TSH) levels within the reference range affect energy expenditure and clinical symptoms and even within the normal range of TSH levels, resting energy expenditure may alter. The aim of the present study was to determine whether treated hypothyroid subjects and healthy subjects with a low-normal TSH range (0.3-2.3 mIU/L) have better clinical outcomes and increased energy expenditure than those with a high-normal TSH range (2.3-4.3 mIU/L).

METHODS

This was a case-control study of 160 overweight/obese women with TSH levels across the reference range of 0.3-4.3 mU/l. Subjects were paired in four groups: healthy subjects with low-normal target TSH (n = 40), healthy subjects with high-normal target TSH (n = 40), subjects with treated hypothyroidism with low-normal target TSH (n = 40), and subjects with treated hypothyroidism with high-normal target TSH (n = 40). Resting energy expenditure (RMR), dietary intake, body composition, physical activity, and biochemical markers were assessed.

RESULTS

Subjects with low-normal (≤2.3 mU/L) and high-normal (>2.3 mU/L) TSH levels did not differ in terms of RMR, serum T3 levels, and clinical symptoms except fatigue (P = 0.013). However, serum fT4 levels were found to be significantly different between the study groups (P = 0.002). Serum fT4 concentration was the highest in subjects with treated hypothyroidism with low-normal target TSH.

CONCLUSION

Variation in serum TSH levels within the reference range did not significantly affect REE and clinical symptoms except fatigue in healthy and women with hypothyroidism.

Effects of Bariatric Surgery on Sarcopenic Obesity Outcomes: A One-Year Prospective Study in Middle-Aged Women

INTRODUCTION

Sarcopenic obesity (SO) is characterised by the confluence of muscle deterioration and high adiposity. When non-surgical interventions prove insufficient, bariatric surgery (BS) becomes the primary approach. This study aimed to address BS effects on SO outcomes 1 year post-surgery among middle-aged women, also considering physical exercise's impact.

METHODS

Prospective single-centre study of 140 patients who underwent Roux-en-Y gastric bypass or sleeve gastrectomy between November 2019 and December 2022. Participants were categorised into tertiles according to SO's diagnosis and severity (group 1-patients with the most severe SO; group 2-intermediate; group 3-the least severe or without SO), calculated considering the consensus issued by ESPEN and EASO in 2022. Evaluations of clinical and biochemical parameters were conducted before and 12 months after BS, and the variation was used for comparative purposes. Body composition was assessed using bone density scans. Linear regression analysis accounted for both surgery type and baseline body mass index (BMI).

RESULTS

Before BS, SO prevalence in the overall sample was 89.3%, decreasing to 2.9% after BS. Group 1 had more body fat mass (56.9 vs 54.8 vs 50.7 kg, p < 0.001), total, trunk and leg fat at baseline and a significantly lower total skeletal muscle mass (47.2 vs 49.4 vs 51.8 kg, p < 0.001). One year post-BS, group 1 presented more weight loss (- 39.8 ± 11.4 kg, p = 0.031), BMI reduction (- 15.9 ± 4.6 kg/m2, p = 0.005) and lost more fat mass (- 32.6 vs - 30.5 vs - 27.9 kg, p = 0.005), but not total skeletal muscle mass (- 5.8 vs - 5.9 vs - 6.8 kg, p = 0.130). Remission rates for comorbidities were substantial among all groups, but more marked among patients within group 1 (type 2 diabetes mellitus 75%, hypertension 47.1% and dyslipidemia 52.8%). Engagement in physical exercise of any kind has increased post-BS (33.1% vs 79.1%).

CONCLUSION

Despite concerns about malabsorptive mechanisms potentially worsening muscle loss, patients with the most severe SO undergoing BS lost more fat mass while experiencing the smallest reduction in total skeletal muscle mass. Remission rates for comorbidities following BS were notable among all groups.

Association between prenatal exposure to per- and polyfluoroalkyl substances and infant anthropometry: A prospective cohort study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic organic chemicals with potential endocrine-disrupting effects, and have been found to impair the physical growth of offspring in both experimental and epidemiological studies. We aimed to investigate the effects of prenatal PFAS exposure on repeated measurements of multiple anthropometric indicators in infants.

METHOD

PFAS were measured in serum samples collected from pregnant women at 12-16 gestational weeks. We calculated z-scores for the weight-for-age (WAZ), weight-for-length (WLZ), head circumference-for-age (HCZ), arm circumference-for-age (ACZ), triceps skinfold-for-age (TSZ), and subscapular skinfold-for-age (SSZ) at birth, 6 months, and 12 months of age according to the child growth standards of the World Health Organization (WHO) for anthropometric indicators. A total of 964 mother-infant pairs were included. A multivariate linear regression was performed to examine the associations between prenatal PFAS concentrations and anthropometric indicators at each time point. A generalized estimating equation (GEE) model was used to examine the longitudinal effects of PFAS exposure on repeated measurements of anthropometric indicators. Ultimately, a Bayesian kernel machine regression (BKMR) model was used to assess the joint effects of the PFAS mixture on anthropometric indicators.

RESULTS

In GEE models, perfluorododecanoic acid (PFDoA) in the high tertile group was associated with increased WAZ/WLZ, with β values (95% confidence intervals (CI)) of 0.12 (0.00, 0.23) and 0.18 (0.03, 0.32), respectively. Perfluorononanoic acid (PFNA) was associated with increased ACZ in the middle and high tertile groups. The BKMR models also presented the associations of the PFAS mixture with increased WAZ/WLZ throughout infancy, with more profound effects in females. Meanwhile, a pattern of inverse associations was observed between the perfluorooctanoic acid (PFOA) concentrations in the high tertile group and decreased WAZ, WLZ, and HCZ in males. In addition, the associations between PFAS and increased TSZ/SSZ at birth were identified by both linear regression and BKMR models.

CONCLUSION

Prenatal PFAS exposure (PFNA and PFDoA) was associated with increased infant anthropometry, especially in female infants, while prenatal PFOA exposure was associated with decreased weight, and head and arm circumference in male infants. The findings indicate that prenatal PFAS exposure may impair the growth trajectory of offspring.

Pituitary crosstalk with bone, adipose tissue and brain

Traditional textbook physiology has ascribed unitary functions to hormones from the anterior and posterior pituitary gland, mainly in the regulation of effector hormone secretion from endocrine organs. However, the evolutionary biology of pituitary hormones and their receptors provides evidence for a broad range of functions in vertebrate physiology. Over the past decade, we and others have discovered that thyroid-stimulating hormone, follicle-stimulating hormone, adrenocorticotropic hormone, prolactin, oxytocin and arginine vasopressin act directly on somatic organs, including bone, adipose tissue and liver. New evidence also indicates that pituitary hormone receptors are expressed in brain regions, nuclei and subnuclei. These studies have prompted us to attribute the pathophysiology of certain human diseases, including osteoporosis, obesity and neurodegeneration, at least in part, to changes in pituitary hormone levels. This new information has identified actionable therapeutic targets for drug discovery.

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.

A Systematic Review and Meta-Analysis of Free Triiodothyronine (FT3) Levels in Humans Depending on Seasonal Air Temperature Changes: Is the Variation in FT3 Levels Related to Nonshivering Thermogenesis?

Thyroid hormones play a crucial role in regulating normal development, growth, and metabolic function. However, the controversy surrounding seasonal changes in free triiodothyronine (FT3) levels remains unresolved. Therefore, the aim of this study was to conduct a systematic review and meta-analysis of variations in FT3 levels in relation to seasonal air temperatures in the context of current knowledge about its role in nonshivering thermogenesis. Ten eligible articles with a total of 336,755 participants were included in the meta-analysis. The studies were categorized into two groups based on the air temperature: "Cold winter", where the winter temperature fell below 0 °C, and "Warm winter", where the winter temperature was above 0 °C. The analysis revealed that in cold regions, FT3 levels decreased in winter compared to summer (I2 = 57%, p < 0.001), whereas in warm regions, FT3 levels increased during winter (I2 = 28%, p < 0.001). These findings suggest that seasonal variations in FT3 levels are likely to be influenced by the winter temperature. Considering the important role of the FT3 in the nonshivering thermogenesis process, we assume that this observed pattern is probably related to the differences in use of thyroid hormones in the brown adipose tissue during adaptive thermogenesis, which may depend on intensity of cold exposure.

Correlation between Subclinical Hypothyroidism and Metabolic Syndrome: A Retrospective Study

Background

Several studies worldwide have studied the correlation between subclinical hypothyroidism (SCH), and metabolic syndrome (MetS), but have reported inconsistent findings.

Objectives

To assess the correlation between SCH and MetS in a population from Saudi Arabia.

Methods

This retrospective study was conducted at King Abdulaziz University Hospital and analyzed all thyroid function tests conducted between January 1, 2019, to December 31, 2021. A predesigned checklist was used to collect data about patients' characteristics such as age, gender, nationality, TSH, FT4 level, and MetS components.

Results

A total of 41,519 thyroid function tests were conducted during the study period. From this, 1303 (3.1%) patients were found to have SCH, with the majority being females (74.4%). The prevalence did not differ according to gender but increased to 3.5% among those aged >60 years. MetS components between mildly and markedly elevated TSH were significant for total cholesterol (P < 0.001) and high-density lipoprotein cholesterol (P < 0.05). Male patients with SCH were at a higher risk of developing diabetes (P < 0.001) and hypertension (P < 0.02), than female patients with SCH. After adjusting for age, in the multiple stepwise linear regression analysis, a significant association was found between TSH levels and ALT (odds ratio: 0.77) and SBP (odds ratio: 0.35).

Conclusion

The study demonstrated that the prevalence of SCH is similar between both genders but increases with age. MetS components were abnormal in patients aged >50 years and in males with SCH. SCH and MetS components were found to be correlated, and thus monitoring these variables in patients with SCH is advisable.

Scientific yoga module for hypothyroidism: A study protocol for tele-yoga RCT

Background

Management of thyroid dysfunction has a direct effect on the quality of life and studies have recognized that hypothyroidism has become a public health challenge. Although conventional medicine is widely used, its long-term side effects are elucidated. This study aims to conduct a randomized controlled trial (RCT) through tele-mode to assess the effectiveness of the newly developed and validated "Scientific Yoga Module" as a telehealth concept for improving the quality of life in patients with hypothyroidism along with management of other symptoms as compared to the standard of care.

Method

This is a single-blinded, two-arm, parallel-group RCT in which at least a total of 120 primary hypothyroid subjects both male and female between the age group 18 to 60 will be recruited from the database of Swami Vivekananda Yoga Anusandhana Samsthana (SVYASA). Participants will be randomly divided into a yoga intervention group (n = 60) and a waitlist control group (n = 60) as per the inclusion and exclusion criteria of the study. A tele-yoga intervention for six months will be administered and pre-interim-post data will be recorded for both groups. This protocol is designed to study the effect of Scientific Yoga Module intervention on primary assessments of SF-36 scale [health-related quality of life (HRQOL) that includes physical, mental, emotional, and social states] along with secondary assessments on the biochemical test of thyroid profile-{Triiodothyronine (T³), Thyroxine (T⁴), Thyroid Stimulating Hormones (TSH)}, Body Mass Index (BMI), Blood Pressure (BP), Fatigue Assessment Scale (FAS), Perceived Stress Scale (PSS), Gita Inventory of personality scale (GIP).

Conclusion

To the best of our knowledge, this tele-yoga RCT for hypothyroidism will be the first clinical trial to analyze the effectiveness of a "Scientific Yoga Module" imparted through tele-mode.

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.

Retrospective cohort analysis comparing changes in blood glucose level and body composition according to changes in thyroid-stimulating hormone level

BACKGROUND

In the euthyroid state, the risk of developing diabetes according to changes in thyroid-stimulating hormone (TSH) levels remains controversial. Additionally, the correlation of various body indices affecting blood glucose levels according to changes in TSH levels over a certain period is not well known.

METHODS

Patients who underwent health check-ups twice at a 2 year interval at a tertiary university hospital between 2009 and 2018 were included. By dividing baseline TSH levels into quartiles (TSH_Q1, Q2, Q3, and Q4), various variables were compared, and their changes after 2 years (∆TSH_Q1, Q2, Q3, and Q4) were confirmed.

RESULTS

Among 15 557 patients, the incidence of diabetes mellitus after 2 years was 2.4% (377/15 557 patients). There was no statistically significant difference in the incidence of diabetes according to TSH_Q (p = 0.243) or ∆TSH_Q (p = 0.131). However, as TSH levels increased, skeletal muscle mass decreased (p < 0.001), and body fat mass and percent body fat significantly increased (p < 0.001). As ∆TSH increased, ∆fasting blood glucose and ∆body mass index also significantly increased (all p < 0.001). The incidence of diabetes decreased significantly as skeletal muscle mass increased (odds ratio 0.734, p < 0.001).

CONCLUSIONS

Owing to the short study period, it was not possible to prove a statistical relationship between the incidence of diabetes mellitus and TSH levels in the euthyroid state. Significant decreases in skeletal muscle mass and increases in body mass index and body fat mass according to baseline TSH levels were demonstrated. Therefore, a focus on improving physical functions, such as increasing muscle mass and decreasing fat, is required in this case.

Association between High Normal TSH Levels and Obesity in Women with Anti-Thyroid Autoantibodies (ATAs)

A positive correlation between Thyroid-Stimulating Hormone (TSH) and Body Mass Index (BMI) has been reported in many studies, but data on this topic remain controversial, especially when TSH values are in the normal range. Moreover, few studies have evaluated the co-existence of thyroid autoimmunity. This study investigated the role of thyroid autoimmunity in the interconnection between TSH, BMI, and waist circumference (WC) in euthyroid patients with overweight or obesity. We enrolled 902 patients (213 males; mean age ± SD: 45 ± 14 years; mean BMI ± SD: 35.8 ± 6.5 kg/m²), with normal serum TSH concentration; anti-thyroid autoantibodies (ATAs) were evaluated in 752 patients (186 males). Patients were divided into four BMI classes, based on WHO criteria, and the relationship between BMI, WC, and TSH was evaluated in the whole sample and compared to ATAs positivity, observed in 235 patients (44 males). No significant difference was found between TSH levels in the BMI classes. A statistically significant correlation between TSH and BMI was found only in ATAs-positive females (N = 191, Spearman rho: 0.149; p-value: 0.040). However, this finding was not confirmed when considering the WC. Our study shows a positive correlation only between TSH and BMI in obese women with positive ATAs, suggesting that in these patients, the high normal levels of TSH could be attributed to a mild thyroid failure with a possible worsening obesity-related effect, and both need a careful evaluation.

Targeting skeletal muscle mitochondrial health in obesity

Metabolic demands of skeletal muscle are substantial and are characterized normally as highly flexible and with a large dynamic range. Skeletal muscle composition (e.g., fiber type and mitochondrial content) and metabolism (e.g., capacity to switch between fatty acid and glucose substrates) are altered in obesity, with some changes proceeding and some following the development of the disease. Nonetheless, there are marked interindividual differences in skeletal muscle composition and metabolism in obesity, some of which have been associated with obesity risk and weight loss capacity. In this review, we discuss related molecular mechanisms and how current and novel treatment strategies may enhance weight loss capacity, particularly in diet-resistant obesity.

Assessment of the Effect of Selenium Supplementation on Production of Selected Cytokines in Women with Hashimoto’s Thyroiditis

The impact of selenium on the course of Hashimoto’s thyroiditis (HT) was mainly assessed by monitoring the titer of antithyroid autoantibodies in most of the studies conducted hitherto. On the other hand, the imbalance in activity of T cells such as Th1, Th2, Th17, and Treg may be relevant in the pathogenesis of this disease. Hence, the assessment of changes in the secretion of cytokines by these cells during selenium supplementation in patients with HT seems to be an important issue and was the main goal of this study. A further aim was to search for correlations among these cytokines, as well as markers of thyroid function, selenium/iodine status in the body, and other biochemical parameters. The group of 29 women with newly diagnosed Hashimoto’s thyroiditis was supplemented with selenium in a dose of 100 µg/day for 6 months. Immunological parameters: interferon γ, tumor necrosis factor α, chemokine CXCL10, interleukin 4, interleukin 1β, interleukin 17, transforming growth factor β, and C-reactive protein, as well as selenium status parameters were determined in serum twice, i.e., before and after supplementation. Selenium supplementation was associated with a change in the production of two cytokines: interferon γ and interleukin 1β, for which a decrease and an increase in concentration were observed, respectively. The partial least squares (PLS) model revealed the presence of many relevant correlations among analyzed parameters. The stage of HT development, degree of thyroid dysfunction, and selenium supplementation of diet are interdependent factors which shape the profile of some cytokines secreted by cells participating in the autoimmunity process.

Thyroid-Stimulating Hormone and Thyroid Hormones and Incidence of Diabetes: Prospective Results of the Brazilian Longitudinal Study of Adult Health (ELSA-BRASIL)

Background: There are conflicting data regarding the association of thyroid function with incident diabetes. We prospectively investigated thyrotropin (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and its conversion ratio (fT3:fT4) with the risk of developing diabetes in euthyroid subjects and those with subclinical thyroid dysfunction. Our hypothesis is that this relationship is a U-shaped curve since both subclinical thyroid diseases may be associated with diabetes. Methods: ELSA-Brasil is a highly admixed cohort study of 35-74 years old at baseline (2008-2010). Levels of TSH, fT4, fT3, and fT3:fT4 ratio were evaluated at baseline and incident diabetes was estimated over an 8.2-year follow-up (2017-2019). Diabetes was identified based on medical diagnosis, prescriptions, and laboratory tests. The risk of diabetes was evaluated according to quintiles of TSH, fT4, fT3, and fT3:fT4 ratio using Poisson regression with robust variance presented as relative risk (RR) with confidence interval [CI] of 95% after multivariable adjustment for sociodemographic and cardiovascular risk factors (reference third quintile), and as continuous variables. Results: We included 7948 participants (mean age, 50.2 [standard deviation 8.6] years; 54.4% female): 7177 euthyroid, 726 with subclinical hypothyroidism, and 45 with subclinical hyperthyroidism. Incidence of diabetes was 14.8%. No association was found for TSH, fT4, fT3, and fT3:fT4 ratio quintiles with incident diabetes. Using continuous variables, the increase of 1-unit (1-U) of fT4 decreased the risk of diabetes (RR 0.94 [CI 0.91-0.99]), while the increase of 1-U of the fT3:fT4 ratio increased the diabetes risk (RR 1.37 [CI 1.15-1.63]). The increase of 1-U of fT3 was associated with an increased risk of diabetes, but without significance after multivariable adjustment. In body mass index-stratified analysis, people with overweight or obesity presented a modest significantly higher risk of diabetes in the lowest quintile of fT4 (RR 1.04 [CI 1.01-1.07]) and an inverse association with incident diabetes in the first quintile of fT3:fT4 ratio (RR, 0.95 [CI 0.93-0.98]). The analyses using continuous variables presented similar findings. Conclusion: These findings suggest that fT4 and fT3 levels and the conversion rate might be additional risk factors associated with incident diabetes, especially in the presence of overweight or obesity. However, they need to be confirmed in future studies. (ClinicalTrials.gov Identifier: NCT02320461).

Association of Anthropometric and Body Adiposity Measures with Thyroid Dysfunction in Clinical Settings of Manipur, Northeast India

Objective This study aimed to understand the association of anthropometric and body adiposity measures with thyroid dysfunction in clinical settings of Manipur, Northeast India.

Materials and Methods The study included 160 Meitei and 152 Thadou-Kuki thyroid dysfunction patients undergoing treatment under medical specialists. Anthropometric data and related adiposity measures were collected along with the medical data.

Results Hypothyroid represents 70.83% and hyperthyroid 29.17% of the total samples included in the study. The incidence of hypothyroid and hyperthyroid, irrespective of ethnic groups, is higher among females (87.49%) than males (12.49%). Hypothyroid individuals are significantly heavier and have higher adiposity measures than hyperthyroid, which is more significantly observed among the Thadou Kuki. Significantly higher waist circumference and weight to height ratio among the hypothyroid patients put the notion of adiposity deposition, apart from just water retention. Ethnic variation in the association reflects socioeconomic intervention in the management of thyroid problems.

Conclusion In conclusion, proper dietary intake or supplements in the course of thyroid dysfunction treatment are important as they can complicate thyroid dysfunction patients with other associated comorbidities.

Thyroid Function Before and After Laparoscopic Sleeve Gastrectomy in Patients with Obesity

BACKGROUND

Effect of laparoscopic sleeve gastrectomy (LSG) on thyroid function of patients with obesity remains unclear. The aim of this study was to evaluate the changes in thyroid function before and after LSG in patients with obesity.

METHODS

Data was retrieved from a retrospectively collected database of patients with morbid obesity and normal thyroid function who received LSG. At 12 months after surgery, changes of thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), and intact parathyroid hormone (iPTH) were evaluated. In addition, the correlation between thyroid hormone levels and body mass index (BMI) and other metabolic indicators and anthropometric parameters were analyzed.

RESULTS

Eighty-five patients were included in the study. The concentrations of FT3 (5.7 ± 0.7 vs 5.1 ± 0.6, p < 0.001) and TSH (2.2 ± 1.0 vs 1.9 ± 0.9, p = 0.002) significantly decreased 12 months postsurgery, while mean FT4 levels increased from12.0 ± 1.9 vs 12.4 ± 2.0 pmol/L (p = 0.013). Furthermore, mean iPTH decreased from 53.3 ± 48.3 to 38.7 ± 13.2 pg/mL (p = 0.011). Multiple stepwise regression analysis showed that changes in LDL levels were an independent factor contributing to changes in TSH levels (β = 0.362, p = 0.001). Moreover, TSH did not correlate with BMI.

CONCLUSIONS

In this study, FT3, TSH, and iPTH were decreased in euthyroid patients with obesity after LSG, while FT4 was significantly increased. Changes in TSH were positively correlated with LDL, but no statistically significant correlation was found with BMI. Additionally, FT3, FT4, and iPTH were correlated with VB12, age, and BMI, respectively.

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.

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 hormones and insulin resistance indices based on the Korean National Health and Nutrition Examination Survey

Thyroid dysfunction has been implicated as a potential pathophysiological factor in glucose homeostasis and insulin resistance (IR). This study aimed to identify the correlation between thyroid dysfunction and IR. We used data from the sixth Korean National Health and Nutrition Examination Survey to evaluate a total of 5727 participants. The triglyceride glucose (TyG) index and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated to represent IR. Correlation analysis was performed between thyroid dysfunction and IR. The log-transformed TSH (LnTSH) and free T4 were significantly correlated with the TyG index (TSH, beta coefficient 0.025, 95% confidence interval [CI] 0.014–0.036, p < 0.001; free T4, − 0.110 (− 0.166 to − 0.054), p < 0.001) but not HOMA-IR. Overt hypothyroidism is correlated with increased TyG index in pre-menopausal females (0.215 (0.122–0.309) p < 0.001). On the other hand, overt hyperthyroidism is correlated with increased HOMA-IR in males (0.304 (0.193–0.416), p < 0.001) and post-menopausal females (1.812 (1.717–1.907), p < 0.001). In euthyroid subjects, LnTSH and TyG index were significantly correlated in females. In conclusion, both hyperthyroidism and hypothyroidism might be associated with IR but by different mechanisms. It might be helpful to assess IR with appropriate indexes in patients with thyroid dysfunction.

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.

Patterns of Bodyweight Changes in Patients With Hypothyroidism, a Retrospective Study From Basrah, Southern Iraq

Background

Weight gain is one of the most important hypothyroidism-related concerns in patients with hypothyroidism. However, unexpectedly, levothyroxine replacement does not necessarily result in body weight (BWT) reduction among those patients. The study aimed to assess the patterns of BWT changes through time in patients with hypothyroidism.

Method

In a retrospective database study from Faiha Specialized Diabetes, Endocrine, and Metabolism Center, a total of 346 adult patients with hypothyroidism (192 newly diagnosed and 154 known hypothyroidism patients) who had one visit every three months, five visits in one year were included. Of these, 116 new and 69 known hypothyroidism patients had completed nine visits in two years. Each visit involved thyroid-stimulating hormone (TSH) and BWT measurements. Patients with chronic liver or renal disease, diabetes mellitus, thyroid cancer, or other malignancies, pregnancy, and steroid or hormonal therapies were excluded. The patients were further subdivided based on average TSH levels into controlled (TSH ≤ 4.2 μIU/ml) and uncontrolled (TSH > 4.2 μIU/ml). Repeated measures analysis of variance (ANOVA) with a Greenhouse-Geisser correction and post hoc tests using the Bonferroni correction were used to evaluate TSH and BWT changes through the study.

Results

Both in newly diagnosed and known hypothyroidism patients with an average TSH > 4.2 μIU/mL, BWT increased significantly through visits over one and two years. For newly diagnosed patients assessed over one year (F(2.41, 321.60) = 3.28, p = 0.03), the mean BWT increase was 1.4 ± 0.38 kg from 3rd to 12th month visits (p = 0.004). For newly diagnosed patients assessed over two years (F(3.10, 263.89) = 9.08, P < 0.0005), the mean BWT increase was 3.02 ± 0.77 kg from 3rd to 24th month visits (p = 0.007). For patients with known hypothyroidism assessed over one year (F(2.56, 187.47) = 7.11, p = 0.0003), the mean BWT increase was 1.97 ± 0.64 kg at 12th month visit, and over two years (F(2.35, 77.56) = 4.67, P = 0.009), the mean BWT increase was 3.78 ± 1.26 kg at 24th month visit. While in all other patients with an average TSH ≤ 4.2 μIU/mL, the BWT changed non-significantly through the visits for newly diagnosed patients over one year and two years (p = 0.10, 0.34, respectively), and known patients over one year and two years (p = 0.47, 0.34, respectively).

Conclusion

Contrary to what is believed, adequate treatment with levothyroxine does not associate with weight reduction. Instead, either the patient kept on the same weight or continued to gain more weight.

Low serum TSH levels are associated with low values of fat-free mass and body cell mass in the elderly

Previous studies on the association between thyroid function and body composition are conflicting and showed strong differences across age groups. Our aim was to clarify age-specific associations of serum thyroid-stimulating hormone (TSH) levels with markers of body composition including body mass index (BMI), waist circumference, fat mass (FM), fat-free mass (FFM) and body cell mass (BCM). We used data from two independent population-based cohorts within the framework of the Study of Health in Pomerania. The study population included 5656 individuals aged 20 to 90 years. Markers of body composition were measured by bioelectrical impedance analysis. Serum TSH levels were significantly positively associated with BMI (β = 0.16; 95% confidence interval [CI]: 0.06 to 0.27), waist circumference (β = 0.35; 95% CI: 0.08 to 0.62) and FM (β = 0.32; 95% CI: 0.12 to 0.52), but not with FFM and BCM. Interaction analysis revealed positive associations of serum TSH levels with BMI, waist circumference, FM, FFM and BCM in individuals older than 60 years, while no such associations were observed in younger individuals. We demonstrated that lower serum TSH levels were accompanied with lower values of BMI, waist circumference, FM, FFM, and BCM in the elderly, while no such associations were observed in younger individuals.

Cumulative Effects of Thyroid Hormones Over 10 Years and Risk of General and Abdominal Obesity

We aimed to assess if changes in thyrotropin (TSH) and free thyroxine (FT4) over 10 years of follow-up would be associated with changes in body mass index (BMI) and waist circumference (WC) or risk of obesity. We enrolled 2317 out of 4179 participants in Tehran Thyroid Study with serum TSH between 0.1-10 mU/l and without history of thyroid medication or surgery. Serum concentrations of FT4 and TSH were measured at baseline and three follow-ups (1999-2011). To account for within-subject correlation, the generalized estimating equation was used to assess the association between one standard deviation(SD) change in the main exposures [cumulative excess (CE)TSH and CEFT4] and changes in BMI and WC; calculated scores of CETSH and CEFT4 were included in models as time-varying exposures. Cumulative excess of TSH or FT4 was not associated with increased incidence of general or abdominal obesity. However, CEFT4 was negatively associated with BMI only in overweight and obese subjects. In GEE analysis, one unit increase in TSH was associated with 0.02 kg/m² increase in BMI (95% CI: 0.01, 0.03), which remained significant only in women; although the association was not significant after adding FT4 to model. One unit increase in FT4 was associated with 1.5 kg/m² decrease in BMI (95% CI:-1.8,-1.2) and 4.1 cm decrease in WC (95% CI:-5.1,-3.1) in both sexes independent of TSH and other confounders. Cumulative excess of TSH or FT4 indicated no risk for general or abdominal obesity. However, FT4 was negatively associated with BMI and WC independent of TSH.

Epigenome-Wide Association Study of Thyroid Function Traits Identifies Novel Associations of fT3 With KLF9 and DOT1L

CONTEXT

Circulating concentrations of free triiodothyronine (fT3), free thyroxine (fT4), and thyrotropin (TSH) are partly heritable traits. Recent studies have advanced knowledge of their genetic architecture. Epigenetic modifications, such as DNA methylation (DNAm), may be important in pituitary-thyroid axis regulation and action, but data are limited.

OBJECTIVE

To identify novel associations between fT3, fT4, and TSH and differentially methylated positions (DMPs) in the genome in subjects from 2 Australian cohorts.

METHOD

We performed an epigenome-wide association study (EWAS) of thyroid function parameters and DNAm using participants from: Brisbane Systems Genetics Study (median age 14.2 years, n = 563) and the Raine Study (median age 17.0 years, n = 863). Plasma fT3, fT4, and TSH were measured by immunoassay. DNAm levels in blood were assessed using Illumina HumanMethylation450 BeadChip arrays. Analyses employed generalized linear mixed models to test association between DNAm and thyroid function parameters. Data from the 2 cohorts were meta-analyzed.

RESULTS

We identified 2 DMPs with epigenome-wide significant (P < 2.4E-7) associations with TSH and 6 with fT3, including cg00049440 in KLF9 (P = 2.88E-10) and cg04173586 in DOT1L (P = 2.09E-16), both genes known to be induced by fT3. All DMPs had a positive association between DNAm and TSH and a negative association between DNAm and fT3. There were no DMPs significantly associated with fT4. We identified 23 differentially methylated regions associated with fT3, fT4, or TSH.

CONCLUSIONS

This study has demonstrated associations between blood-based DNAm and both fT3 and TSH. This may provide insight into mechanisms underlying thyroid hormone action and/or pituitary-thyroid axis function.

Visceral and subcutaneous adipose tissue, which one induced thyroid dysfunction in patients with morbid obesity

BACKGROUND

Thyroid dysfunction in patients with morbid obesity usually resolves after bariatric surgery. However, the role of diverse types of adipose tissue in the process remains unknown.

OBJECTIVES

We aim to investigate the effects of visceral and subcutaneous fat on thyroid function in a Chinese population with morbid obesity who underwent sleeve gastrectomy (SG).

SETTING

University hospital, Shanghai, China METHODS: Repeated measurement data of thyroid hormone and body fat were collected at 0, 3, 6, 12, 24, and 36 months after sleeve gastrectomy. Dual-energy X-ray absorptiometer and quantitative computerized tomography (CT) were used to compute visceral fat and subcutaneous fat. Repeated measures correlation (rmmcorr) package was employed for correlation analysis with generalized additive mixed model (GAMM) determining the independent factors.

RESULTS

Thyroid stimulating-hormone (TSH) showed notable decrease at 36 months after surgery, coupled with reduction of BMI (38.08 kg/cm² versus 24.28 kg/cm²), C-reactive protein (CRP), visceral adipose tissue (786.74 cm² versus 367.44 cm²), body fat rate, and waistline (118.13 cm versus 100.87 cm). Only visceral fat, diabetes, and CRP proved to be independent variables for TSH decline, without correlation with subcutaneous fat.

CONCLUSION

The present study is first to report the effects of different types of body fat on thyroid function in a Chinese population with morbid obesity, revealing that loss of visceral fat is the key to improving endocrine and metabolic activity after bariatric surgery.

Determination of age and sex specific TSH and FT4 reference limits in overweight and obese individuals in an iodine-replete region: Tehran Thyroid Study (TTS)

Introduction: To determine age and sex-specific thyrotropin (TSH) and free thyroxine (FT4) reference ranges according to body mass index (BMI) categories. Methods: With regards to the National Academy of Clinical Biochemistry (NACB) criteria, a total of 2818 individuals from the Tehran Thyroid Study population was selected and categorized in three BMI groups. Results: TSH levels did not differ significantly between BMI groups (p = .054). Females had statistically higher TSH levels than males in all BMI categories (p < .001). According to age-specific analyses, the youngest category (20-29 years) had the highest median values of serum TSH in all BMI groups. With increasing BMI, the 2.5^th percentile of TSH remained approximately unchanged and the 97.5^th percentile showed an increasing pattern. FT4 level was significantly higher in the normal weight group compared to obese individuals (p < .001); females had significantly lower FT4 levels than males in normal weight and obese groups (p < .001). According to age categories, the youngest group (20-29 years) had higher levels of FT4 than the elderly group in all BMI categories. A decreasing pattern in both 2.5^th and 97.5^th percentiles of FT4 was observed along with increasing BMI. Conclusions: Compared to the normal weight population, obese individuals have slightly lower FT4 concentrations accompanied by similar TSH levels. With increasing BMI, upper limits of TSH and FT4 show increasing and decreasing patterns, respectively.

Body mass index (BMI) is associated with serum thyroid-stimulating hormone (TSH) level in infertile women: a cross-sectional study

Studies suggest that there is a relationship between body mass index (BMI) and thyroid-stimulating hormone (TSH) levels. But conflicting evidence exists regarding the relationship between the two variables. Moreover, thyroid function is closely related to female fertility and has certain effects on infertility. Therefore, the present study will explore the relationship between BMI and TSH levels in patients with infertility in our center. We retrospectively analyzed relevant indicators of 2,789 in Tubal Factor Infertility patients undergoing assisted reproduction technology from January 2016 to December 2018 in our center in order to analyze the relationship between BMI and serum TSH level. The medical histories of patients were reviewed. The relationship between BMI and TSH was assessed using smooth curve fitting and multivariate regression model. The smoothing curve fitting between BMI and TSH exhibited a non-linear relationship, and the resulting curve exhibited a two-stage change and a breakpoint. By multivariate piecewise linear regression, we found that the TSH level was increased with the increase of BMI when the BMI was greater than 25.3 kg/m² (β 0.06, 95% CI 0.02, 0.01; p = 0.0028). In contrast, the TSH level was decreased with the increase of BMI when the BMI was less than 25.3 kg/m² (β -0.02, 95% CI -0.05, 0.00; p = 0.0573). Collectively, our study described a non-linear relationship between BMI and TSH level in infertile patients after adjustment of potential confounders. However, such causal relationship between BMI and TSH in infertile women still needs to be further clarified in future investigations.

Thyroid Hormone Changes After Sleeve Gastrectomy With and Without Antral Preservation

BACKGROUND

The effect of bariatric surgery on thyroid hormone changes yielded inconsistent results. The aim of the present study was to assess the change of thyroid hormone levels following laparoscopic sleeve gastrectomy (LSG), with or without antral preservation (AP).

METHODS

Thyroid hormones (TSH, FT3, FT4) were examined preoperatively, at the end of the first postoperative month, and first postoperative year. Secondly, antral resection (AR) and AP were compared at inducing weight loss and thereby affecting thyroid hormone levels.

RESULTS

Euthyroid obese patients (86 female/20 male) underwent LSG. Of these, 58 patients underwent AR and 48 patients AP. The mean FT3 levels significantly decreased both in the first postoperative month and the first year (P < 0.001), whereas mean TSH levels decreased significantly in the first postoperative year (P < 0.001). FT4 levels remained nearly unchanged (P = 0.517). Postoperative first year body mass index (BMI) loss, excess BMI loss percentile (%EBMIL), and total body weight loss percentile (%TWL) were significantly higher in AR group than the AP group (P ≤ 0.01). When the change in thyroid hormone levels was analyzed by pyloric distance according to time periods, no significant difference was found in TSH and FT4 levels (P > 0.05); however, reduction in FT3 levels was significantly greater in patients with AR than in AP patients (P = 0.028).

CONCLUSION

LSG promotes significant reduction in TSH and FT3 levels, whereas FT4 levels remain unchanged. LSG with AR provides more weight loss in short term and appears to be more effective at lowering FT3 levels.

Possible Effects of Perchlorate Contamination of Drinking Water on Thyroid Health

Background

Perchlorate is an anion that occurs as a contaminant in groundwater. It originates from the improper disposal of ammonium perchlorate, a component of rocket fuel. The objective of this study was to explore whether the exposure to perchlorate in drinking water had an impact on the thyroid function of the population residing near an ammonium perchlorate plant in Kerala. Methodology. Using an ecological study design, we compared the serum levels of thyroid-stimulating hormone, thyroxine, and thyroid peroxidase antibodies among a representative sample of 289 study subjects from the area surrounding the ammonium perchlorate enrichment plant to 281 study subjects in a control area.

Results

The perchlorate concentration in the groundwater varied from 1600 ppb to 57,000 ppb in the 10 samples from the contaminated area and was below 24 ppb in all locations in the control area. No significant differences were found in the mean serum TSH concentration and mean T4 levels between the subjects from the contaminated area and the control area. On regression analysis, perchlorate contamination was not found to be a significant predictor of TSH.

Conclusion

This study did not find any significant association between perchlorate in drinking water and changes in thyroid hormone levels. Our findings indicate the need for further investigation of this hypothesis using urinary perchlorate as a measure of individual exposure.

Association between TSH levels within the reference range and adiposity markers at the baseline of the ELSA-Brasil study

Background

The association of thyrotropin (TSH) with overall (body mass index, BMI), visceral (waist circumference and steatosis), and upper subcutaneous (neck circumference, NC) adiposity markers is still controversial, and the aim of this study is to assess these associations in the baseline data of a large cohort from ELSA-Brasil.

Methods and findings

This cross-sectional study included 11,224 participants with normal thyroid function (normal TSH levels). BMI, waist circumference, NC and steatosis, defined by hepatic attenuation (mild or moderate/severe) were the explicative variables. TSH levels were log transformed (logTSH), and multivariate linear regression models were generated to estimate the associations between logTSH and BMI (continuous and categorized), waist circumference, NC, and steatosis after adjusting for sociodemographic characteristics, health behaviors, and comorbidities. The mean age was 51.5±8.9 years, 5,793 (51.6%) participants were women, 21.8% (n = 2,444) were obese, and 15.1% of the sample was TPOAb positive. The TSH levels were significantly higher in the obese group than in the reference group (<25.0 kg/m²). In the multivariable linear regression models, significant associations of logTSH with BMI and obesity were found. LogTSH was associated with waist circumference only among women. NC and steatosis were not related to TSH levels.

Conclusions

TSH levels were associated with overall adiposity and obesity. Further studies may elucidate reference levels of TSH according to BMI status.

The Association of Obesity with Autoimmune Thyroiditis and Thyroid Function-Possible Mechanisms of Bilateral Interaction

A growing number of patients suffer from autoimmune diseases, including autoimmune thyroid disease. There has simultaneously been a significant increase in the prevalence of obesity worldwide. It is still an open question whether adiposity can directly influence activation of inflammatory processes affecting the thyroid in genetically predisposed individuals. Adipokines, biologically active substances derived from the adipocytes, belong to a heterogenic group of compounds involved in numerous physiological functions, including the maintenance of metabolism, hormonal balance, and immune response. Notably, the presence of obesity worsens the course of selected autoimmune diseases and impairs response to treatment. Moreover, the excess of body fat may result in the progression of autoimmune diseases. Nutritional status, body weight, and energy expenditure may influence thyroid hormone secretion. Interestingly, thyroid hormones might influence the activity of adipose tissue as metabolic alterations related to fat tissue are observed under pathological conditions in which there are deficits or overproduction of thyroid hormones. Functioning TSH receptors are expressed on adipocytes. Thermogenesis may presumably be stimulated by TSH binding to its receptor on brown adipocytes. There could be a bilateral interaction between the thyroid and adipose. Obesity may influence the onset and course of autoimmune disease.

The Association Between Serum Thyrotropin Within the Reference Range and Metabolic Syndrome in a Community-Based Chinese Population

PURPOSE

We aimed to ascertain the association between thyrotropin (TSH) levels in euthyroid state and the prevalence of metabolic syndrome (MetS) in a community-based Chinese population.

PARTICIPANTS AND METHODS

Based on a large and well-characterized community cohort in Beijing, China, 1831 men and 1742 women with serum TSH levels within the reference range (0.50-4.78 µIU/mL) were stratified by quartiles of TSH (Q1-4). MetS was identified according to the criteria of International Diabetes Federation guidelines. Poisson regression models were used to estimate the association between serum TSH and the prevalence of MetS and its components before and after adjustment for potential confounding factors. The reported association was measured using the prevalence ratio (PR) with its respective 95% confidence interval (95% CI).

RESULTS

The prevalence of MetS in euthyroid population across TSH quartiles (Q1-4) was 38.9%, 44.6%, 41.0%, and 47.7%, respectively, in men (P = 0.045), and 47.7%, 46.6%, 46.9%, and 54.6%, respectively, in women (P = 0.032). Compared with the reference group TSH-Q1, the prevalence of MetS was higher among TSH-Q4 group both in men (PR = 1.27; 95% CI: 1.09, 1.48, P = 0.002) and women (PR = 1.21; 95% CI: 1.07, 1.37, P = 0.003) even after adjustment for age, lifestyle factors, serum levels of free triiodothyronine (FT3), and free thyroxine (FT4). Most of the components of MetS were common in higher serum TSH levels within the normal range.

CONCLUSION

The prevalence of MetS and most of its components increased in the higher TSH group in euthyroid Chinese population.

Weight loss efficacy of alternate day fasting versus daily calorie restriction in subjects with subclinical hypothyroidism: a secondary analysis

This study compared the weight loss efficacy of alternate-day fasting (ADF) versus daily calorie restriction (CR) in adults with subclinical hypothyroidism. After 6 months, body weight decreased (P < 0.001) similarly by ADF (-7% ± 1%) and CR (-8% ± 2%). Insulin resistance decreased (P < 0.05) more by ADF versus CR. Free thyroxin and thyroid-stimulating hormone remained unchanged. Thus, ADF and CR produce similar weight loss in this population, without affecting thyroid hormone levels. Novelty Intermittent fasting and daily restriction produce similar reductions in body weight in subjects with subclinical hypothyroidism.

Thyroid disease and the metabolic syndrome

PURPOSE OF REVIEW

To summarize recent developments in the association of thyroid function with metabolic syndrome (MetS).

RECENT FINDINGS

Although thyroid hormones even within low normal range are associated with various metabolic abnormalities, the risk of MetS remains a controversial issue. Hyperthyroid state might be associated only with insulin resistance and dysglycemia. Autoimmune thyroid diseases may be a potential risk factor for metabolic abnormalities even in those with low normal thyroid function.

SUMMARY

The interrelation between thyroid stimulating hormone, free T3, freeT4 and metabolic parameters is complex and might be affected by age, sex, BMI, insulin resistance, smoking, iodine intake and inflammatory markers.

Sex-Dependent Association between Weight Change and Thyroid Dysfunction: Population-Level Analysis Using the Korean National Health and Nutrition Examination Survey

BACKGROUND

Although body weight change (BWC) is a common manifestation of thyroid dysfunction, solid evidence for whether to perform or on whom to perform thyroid function test in subjects complaining of BWC is lacking.

OBJECTIVE

To evaluate the association between thyroid dysfunction and BWC using a nationwide survey.

METHOD

Data was obtained from the Korea National Health and Nutrition Examination Survey VI 2013-2015 and 5,456 subjects without previous thyroid disease were included. Serum thyroid-stimulating hormone (TSH), free T4, and self-reported BWC during the previous year were used for the evaluation. Weight loss or gain was defined as weight change of at least 3 kg.

RESULTS

In total, 1,017 men (37.3%) and 1,175 women (43.0%) reported BWCs during the previous year. The overall weighted prevalence of thyroid dysfunction was not significantly associated with the extent of BWC in men (p = 0.705) or women (p = 0.094). However, when the impact of TSH levels on weight change was separately evaluated for weight gain and loss after adjusting for age and body mass index in each sex, weight loss in women was significantly associated with TSH levels (hazard ratio 0.64, 95% CI 0.47-0.85, p = 0.03). No association of thyroid dysfunction was observed for weight gain in women (p = 0.23) or any changes in men (p = 0.875 in weight gain, p = 0.923 in weight loss).

CONCLUSIONS

This study highlights the necessity of performing thyroid function testing in women who complain of weight loss, but such testing may be less vital in women with weight gain or men with any changes in weight.

Association between serum thyrotropin within the euthyroid range and obesity

The relationship between variations in thyroid function and indices of obesity remains a focus of debate. To explore the associations between thyroid function within the normal range and obesity and to evaluate potential modifying factors, we analyzed a large and well-characterized community cohort in Beijing, China, containing 1,816 men and 1,774 women with serum thyrotropin (TSH) levels within the reference range (0.55-4.78 μIU/mL). Associations between TSH levels and BMI were identified using correlation analysis, ANOVA and Chi-square tests. Logistic regression analyses were used to estimate the impact of serum TSH on obesity before and after adjustment for possible confounding factors. The mean serum TSH was 2.04 ± 0.94 μIU/mL. TSH within the reference range was positively associated with BMI in both genders. Compared with euthyroid adults whose TSH was in the middle quartiles (TSH 1.30-2.60 μIU/mL) of the reference range, the odds of obesity (BMI ≥ 28.0 kg/m²) and severe obesity (BMI ≥ 33.0 kg/m²) was 38% (OR = 1.38, 95% CI 1.17-1.64) and 58% (OR = 1.58, 95% CI 1.12-2.21) more likely, respectively, among those with TSH in the upper quartile. For women, postmenopausal subjects with lower TSH levels had a lower risk of severe obesity (OR = 0.42, 95% CI 0.20-0.91) than those in the middle TSH quartile. Positive associations were found between serum TSH within the euthyroid range and obesity, and menopause showed a significant influence on the relationship between TSH level and severe obesity.

Thyroid function is associated with body mass index and fasting plasma glucose in Thai euthyroid population

AIMS

Several population-based studies found the associations between body mass index and thyroid function within the normal range. Furthermore, these thyroid functions are related with insulin resistance and plasma glucose levels. This study aimed to investigate the associations between thyroid functions and metabolic parameters in Thai euthyroid population.

METHODS

Participants from the Thai National Thai Health Examination Survey were randomly measured for TSH, FT4, anti-thyroperoxidase, and anti-thyroglobulin. Euthyroidism was defined by TSH 0.27-4.20 mIU/L and FT4 0.93-1.71 ng/dL.

RESULTS

A total of 2242 euthyroid participants were included. Fifty-one percent were female. Mean age, fasting plasma glucose, and body mass index were 55 ± 21 years, 93 ± 29 mg/dL, and 23.4 ± 4.6 kg/m², respectively. Multivariate regression analysis after age and sex adjustment showed a negative association of serum FT4 with body mass index (β = -0.070, p = 0.001) and the relationship was still significant after subjects with positive anti-thyroperoxidase were excluded (β = -0.068, p = 0.003). In contrast, serum TSH was positively associated with body mass index (β = 0.052, p = 0.012). Moreover, serum FT4 was positively associated with fasting plasma glucose levels (β = 0.097, p < 0.001).

CONCLUSIONS

Small variations of serum TSH and FT4 within the reference range may contribute to the differences in metabolic indexes such as body mass index and fasting plasma glucose.

Lack of Influence of Thyroid Hormone on Bone Mineral Density and Body Composition in Healthy Euthyroid Women

Objective: The objective of this study was to evaluate whether evolution of bone mineral density (BMD) is associated with the thyroid hormone profile in a cohort of euthyroid women with no other known diseases within 1 year. Methods: This was a prospective cohort study conducted at the University of Campinas, Brazil. We used a database with 52 women aged 20-39 who were followed for 1 year in a family planning outpatient clinic. The inclusion criteria were body mass index (BMI) <30 kg/m², no known diseases/medication use, fasting glucose <100 mg/dl, and 2 h glucose after a 75 g oral glucose load <140 mg/dl. The women were divided into groups of normal weight (n = 30) and overweight (n = 22). The main outcomes were BMD measured by dual-energy x-ray absorptiometry (DXA) and thyroid hormone profile (thyrotropin TSH, free triiodothyronine FT3, free thyroxine FT4, and T3/T4 ratio); other variables were body composition (DXA), calcium metabolism markers, and life habits. We used a repeated measures analysis of variance (ANOVA) and multiple regression analyses to evaluate associations. Results: At the baseline data collection, overweight women showed a higher T3/T4 ratio, leptin, calcium, BMD in the lumbar spine and total femur, total mass, mass, and percentage of fat mass than normal weight women. At 12 months, both groups had increased FT4, calcium, ALP, femoral neck BMD, and total mass by time effect. The normal weight group presented a decrease of vitamin D when compared to the baseline. Increased BMD of the femoral neck was associated with moderate coffee intake, and as such, there were no associations found between this increase and the thyroid hormone profile. Leptin and ALP were associated with total mass variation, while leptin and PTH were associated with fat mass variation. The normal BMI was inversely associated with the variation of total mass, mass, and percentage of fat mass, and engaging in regular physical activity was inversely associated with fat mass variation. Conclusions: In this sample of euthyroid healthy women who were both normal weight and overweight, the thyroid hormone profile was not associated with variations in bone mineral density and body composition after a 1 year follow-up.

Decreased Leptin Is Associated with Alterations in Thyroid-Stimulating Hormone Levels after Roux-en-Y Gastric Bypass Surgery in Obese Euthyroid Patients with Type 2 Diabetes

BACKGROUND

Leptin has been shown to stimulate the hypothalamus-pituitary-thyroid (HPT) axis in vivo and vitro. Its role in thyroid axis regulation after weight loss induced by bariatric surgery is still unknown. The aim of this study was to evaluate the influence of leptin on weight loss and thyroid function variation induced by Roux-en-Y gastric bypass (RYGB) surgery in euthyroid individuals with obesity and type 2 diabetes mellitus (T2DM).

METHODS

65 Chinese individuals with obesity and T2DM who underwent RYGB, and 27 healthy volunteers were enrolled in this retrospective study. Participants were evaluated for changes in anthropometric parameters, metabolic indexes, thyroid function, and leptin levels before and 12 months after surgery.

RESULTS

After RYGB, all of these patients experienced significant weight reduction and improved glucose control. Metabolic parameters were significantly ameliorated after surgery compared with baseline. Thyroid hormones including free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) declined in parallel. Median (IQR) plasma leptin levels decreased from 33.7 ng/mL (17.9-63.1) to 10.3 ng/mL (4.0-18.5). Pearson correlation analysis showed that TSH was significantly positively correlated with body mass index, C-reactive protein (CRP), and leptin. Multiple stepwise linear regression indicated that leptin and CRP were independent factors affecting TSH. The β coefficients were 0.38 (p = 0.001) and 0.32 (p = 0.004), respectively. There was a significant positive correlation between ΔTSH and Δleptin (r = 0.33, p = 0.01).

CONCLUSION

Decreased or normalized TSH levels after weight loss induced by RYGB might be mediated by the decline in leptin. There could be cross talk between adipose tissue and the HPT axis.

Age and Gender Specific Thyroid Hormones and Their Relationships with Body Mass Index in a Large Chinese Population

OBJECTIVES

To investigate the associations of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) with body mass index (BMI) and the effect of age and gender on these relationships in a large Chinese population.

METHODS

A total of 97,997 individuals from a health examination center were selected. The medians (25th and 75th) of TSH, FT3 and FT4 were used to explore the trends based on gender, 10-year age groups and BMI. The relationships of TSH, FT3 and FT4 with BMI were assessed by generalized additive models (GAM) along with adjusting the effect of age and gender.

RESULTS

After applying our exclusion criteria, 77,991 euthyroid participants (45,428 males and 32,563 females) were analyzed. The medians of TSH level based on BMI groups were significantly higher in female participants than those in males in all age groups (P < 0.05), and the median FT3 level was lower in female subjects; however, there was no significant difference between male and female subjects in median FT4 level. The GAM analysis showed the non-linear positive association of TSH and FT3 with BMI, and these relationships were markedly influenced by age and gender. However, FT4 had a negative relationship with BMI, with neglectable effect of age and gender.

CONCLUSIONS

TSH, FT3 and BMI have a non-linear and positive quadratic relationship after age and gender adjustment. FT4, however, has a negative non-linear relationship with BMI with neglectable influence of age and gender.

Loss of μ-crystallin causes PPARγ activation and obesity in high-fat diet-fed mice

The thyroid hormone-binding protein μ-crystallin (CRYM) mediates thyroid hormone action by sequestering triiodothyronine in the cytoplasm and regulating the intracellular concentration of thyroid hormone. As thyroid hormone action is closely associated with glycolipid metabolism, it has been proposed that CRYM may contribute to this process by reserving or releasing triiodothyronine in the cytoplasm. We aimed to clarify the relationship between CRYM and glycolipid metabolism by comparing wild-type and CRYM knockout mice fed a high-fat diet. Each group was provided a high-fat diet for 10 weeks, and then their body weight and fasting blood glucose levels were measured. Although no difference in body weight was observed between the two groups with normal diet, the treatment with a high-fat diet was found to induce obesity in the knockout mice. The knockout group displayed increased dietary intake, white adipose tissue, fat cell hypertrophy, and hyperglycemia in the intraperitoneal glucose tolerance test. In CRYM knockout mice, liver fat deposits were more pronounced than in the control group. Enhanced levels of PPARγ, which is known to cause fatty liver, and ACC1, which is a target gene for thyroid hormone and is involved in the fat synthesis, were also detected in the livers of CRYM knockout mice. These observations suggest that CRYM deficiency leads to obesity and lipogenesis, possibly in part through increasing the food intake of mice fed a high-fat diet.

Association between Thyroid-Stimulating Hormone Levels and Non-Alcoholic Fatty Liver Disease Is Not Independent from Metabolic Syndrome Criteria

INTRODUCTION

Thyroid hormones are involved in the regulation of body composition, lipid metabolism, and insulin resistance. Thus, it is possible that they might play a role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the role of thyroid function on NAFLD is not well defined. In this study, we evaluated the relationship between thyroid-stimulating hormone (TSH) levels, within the reference range, and presence of NAFLD in asymptomatic individuals.

STUDY DESIGN

We included all individuals evaluated at a preventive clinic of the Hospital Israelita Albert Einstein, between 2014 and 2015. The prevalence of NAFLD (analyzed by abdominal ultrasound), according to TSH quartiles, within the reference range, was determined. The association between TSH quartiles and NAFLD was analyzed by logistic regression adjusted for possible confounders.

RESULTS

We evaluated 10,539 individuals (73% male, age 43.4 ± 9.4 years). The prevalence of NAFLD was 34, 38, 38, and 39% in the first to the fourth TSH quartiles (0.46-1.44, 1.45-1.97, 1.98-2.68, and 2.69-4.68 mUI/L, respectively, p for trend < 0.001). At univariate analysis, higher TSH levels were associated with the diagnosis of NAFLD. When data were adjusted for the metabolic syndrome characteristics (waist circumference, HDL-cholesterol and triglycerides levels, presence of diabetes, and systemic arterial hypertension), the association was no longer significant.

CONCLUSIONS

Although the TSH variability within the reference range is associated with NAFLD in univariable models, once adjusted for metabolic syndrome factors no significant association is noted.

Reference intervals of thyroid hormones in a previously iodine-deficient area in Darfur, Sudan

BACKGROUND

Thyroid-stimulating hormone (TSH), thyroxin (T4) and T3 levels are varied in the different settings with disorders of thyroid homeostasis. It is recommended that every setting has to establish its own reference intervals (RIs) for these hormones.

METHODS

A multi-stage stratified sampling method was used to select a representative sample of a Sudanese adult (>20 years of age) in Nyala in western Sudan in the Darfur region during the period between January and June 2016 to establish RIs of thyroid-related hormones (TSH, T4 and T3).In this study, 1753 serum samples (male and female) with different age groups were investigated. A radioimmunoassay gamma counter was used to measure the level of these hormones.

RESULTS

The median (95% intervals) of serum TSH, T4 and T3 levels was 1.2 (0.50-3.0) mIU/l, 111.0 (72.0-161.0) nmol/l and 1.5 (0.8-2.8) nmol/l respectively.While the level of TSH was significantly higher in the age group between 31 and 40 years, both T4 and T3 levels have shown a progressive increase with age. There was no significant difference in the TSH, T4 and T3 level when the RIs were compared between males and females.

CONCLUSION

The RIs for TSH, T4 and T3 in this setting were different from the levels provided by the manufacturers. The RIs were different in the different age groups.

Exploration of Patient Characteristics and Quality of Life in Patients with Lipoedema Using a Survey

INTRODUCTION

Lipoedema is a chronic disorder in which excessive fat distribution occurs predominantly from the waist down, resulting in a disproportion between the lower extremities and upper torso. Lipoedema is often not recognized, while patients experience pain and easy bruising. As a long-term condition, lipoedema has a massive effect on patients' lives and mental health. The aim of this study is to explore patient characteristics, quality of life, physical complaints and comorbidities in patients with lipoedema.

METHODS

A survey was conducted by email amongst lipoedema patients, consisting of informed consent and multiple questionnaires. The questionnaires included general patient characteristics, physical complaints, comorbidities, RAND-36 and EQ-5D-3L. Participants who responded to a message on the Dutch Lipoedema Association website were recruited.

RESULTS

All lipoedema patients experience physical complaints, with pain (88.3 %) and easy bruising (85.9 %) as primary complaints. The diagnosis was mostly made by a dermatologist after visiting a mean of 2.8 doctors. Furthermore, mean time from onset until diagnosis was 18 years. Quality of life (59.3) was significantly lower than the Dutch female average (74.9; p < 0.001). Additionally, patients with comorbidities had significant lower quality of life (RAND 54.7, p < 0.001).

CONCLUSIONS

Lipoedema patients often have severe complaints and experience lower quality of life regarding physical, emotional and social functioning. Additionally, comorbidities have a large impact on quality of life.

Thyroid-Stimulating Hormone, Degree of Obesity, and Metabolic Risk Markers in a Cohort of Swedish Children with Obesity

BACKGROUND/AIMS

Thyroid-stimulating hormone (TSH) is affected in obesity and might influence metabolic risk. It is unclear what mechanisms cause elevated TSH in obesity. We aimed to investigate TSH status within the normal range and the association of TSH with degree of obesity and metabolic parameters in children with obesity.

METHODS

A total of 3,459 children, aged 3.0-17.9 years, were identified in the Swedish Childhood Obesity Treatment Registry, BORIS. Age, gender, TSH, free triiodothyronine (fT3), free thyroxine (fT4), body mass index standard deviation scores (BMI SDS), as well as variables of lipid and glucose metabolism were examined.

RESULTS

Children with high-normal TSH (>3.0 mU/L) (28.8%) had higher BMI SDS compared to children with low-normal TSH (<3.0 mU/L) (p < 0.001). Multivariable regression analysis adjusted for age and gender showed that TSH levels were associated with BMI SDS (β: 0.21, 95% CI: 0.14-0.28, p < 0.001). Associations of thyroid hormones with markers of lipid and glucose metabolism were observed, where TSH was associated with fasting insulin, HOMA (homeostatic model assessment of insulin resistance), total cholesterol, and triglycerides.

CONCLUSIONS

A positive association between TSH levels and BMI SDS was seen in children with obesity. Associations of TSH and free thyroid hormones with glucose metabolism indicated that TSH might be one of several factors acting to determine body weight and obesity co-morbidities, although the underlying mechanism remains unclear.

Effect of Weight Loss after Bariatric Surgery on Thyroid-Stimulating Hormone Levels in Patients with Morbid Obesity and Normal Thyroid Function

BACKGROUND

Several studies have reported that morbid obesity is associated with increased thyroid-stimulating hormone (TSH) levels. However, it is not clear what is the impact of bariatric surgery on postoperative thyroid function. The aim of this study was to evaluate the effect of weight loss after bariatric surgery on TSH levels in euthyroid patients with morbid obesity.

METHODS

We performed a retrospective observational study of 949 euthyroid patients (86.1% female; age 42.0 ± 10.3 years, BMI 44.3 ± 5.7 kg/m²) with morbid obesity submitted to bariatric surgery (laparoscopic adjustable gastric band, Roux-en-Y gastric bypass, or sleeve gastrectomy). Patients were subdivided in two groups: normal TSH group (TSH <2.5 mU/L) and high-normal TSH group (TSH ≥2.5 mU/L). The impact of anthropometric parameters, comorbidities, TSH, free thyroxine (FT4), free triiodothyronine (FT3), type of surgery, and excessive body weight loss (EBWL) on TSH variation 12 months after surgery was evaluated.

RESULTS

The high-normal TSH group (24.3% of patients) included more women, presented a higher BMI, higher systolic blood pressure, and higher FT3 levels. There was a significant decrease of TSH 12 months after surgery that was more marked in the high-normal TSH group (normal TSH group: 1.57 ± 0.49 to 1.53 ± 0.69 mIU/L, p = 0.063; high-normal TSH group: 3.23 ± 0.59 to 2.38 ± 0.86 mIU/L, p < 0.001). In a multivariate analysis, after adjusting for relevant covariates, EBWL, baseline BMI, and baseline FT3 were significantly associated with TSH decrease 12 months after bariatric surgery.

CONCLUSION

Bariatric surgery promotes a decrease of TSH that is significantly greater in patients with high-normal TSH and is independently associated with EBWL after surgery.

Preoperative thyroid function and weight loss after bariatric surgery

Thyroid function has an important role on body weight regulation. However, the impact of thyroid function on weight loss after bariatric surgery is still largely unknown. We evaluated the association between preoperative thyroid function and the excess weight loss 1 year after surgery, in 641 patients with morbid obesity who underwent bariatric surgery. Patients with a history of thyroid disease, treatment with thyroid hormone or antithyroid drugs and those with preoperative evaluation consistent with overt hypothyroidism or hyperthyroidism were excluded. The preoperative levels of TSH and FT4 were not associated with weight loss after bariatric surgery. The variation of FT3 within the reference range was also not associated with weight loss. In contrast, the subgroup with FT3 above the reference range (12.3% of patients) had a significantly higher excess weight loss than patients with normal FT3. This difference remained significant after adjustment for age, sex, BMI, type of surgery, TSH and FT4. In conclusion, we observed an association between high FT3 and a greater weight loss after bariatric surgery, highlighting a group of patients with an increased benefit from this intervention. Our results also suggest a novel hypothesis: the pharmacological modulation of thyroid function may be a potential therapeutic target in patients undergoing bariatric surgery.