Thyroid and leptin

Higher Parametric Thyroid Feedback Quantile-based Index Is a Predictor of Type 2 Diabetes in a German Population Sample

CONTEXT

Type 2 diabetes has been described to be associated with hypothyroidism but we recently found that a decrease in pituitary sensitivity to thyroid hormone is associated with diabetes, obesity, and metabolic syndrome.

OBJECTIVE

We aimed to assess the longitudinal nature of this association in the population-based Study of Health in Pomerania (SHIP) in Germany.

METHODS

Among a population-based sample of 4308 participants aged 20 to 79 years, 77% were followed for a period of 5 years. We studied 2542 participants without diabetes or thyroid medication at baseline and complete data in the variables of interest. Data of baseline free thyroxine (fT4) and thyrotropin (TSH) were used to calculate the Parametric Thyroid Feedback Quantile-based Index (PTFQI), which measures whether TSH remains elevated despite fT4 being high. It uses the average population response as reference. PTFQI association with incidence of type 2 diabetes over 5 years was estimated with Poisson regression models adjusted for age, sex, and body mass index (BMI).

RESULTS

Compared with the first PTFQI quartile, incidence rate ratios for diabetes were 1.54 (95% CI, 0.97-2.46), 1.55 (0.94-2.57), and 1.97 (1.27-3.10) for the upper quartiles (P trend = .004) after adjusting for age and sex. The association remained statistically significant after additionally adjusting for BMI: 1.64 (1.05-2.59) for the fourth vs the first quartile (P trend = .043).

CONCLUSION

An elevation of the pituitary TSH-inhibition threshold is associated with incident type 2 diabetes independently of BMI. The PTFQI might have clinical potential for prognosis and metabolic status monitoring.

Weight Loss Improved Hypothalamic GH Deficiency but not Hypogonadotropic Hypogonadism in a Man With Down Syndrome

Down syndrome (DS) is associated with several endocrine disorders, including diabetes, obesity, and primary hypogonadism. Here, we present a man with DS who manifested with atypical hypogonadotropic hypogonadism and in whom weight loss resulted in the improvement of hypothalamic GH deficiency. A 27-year-old man with DS and severe obesity was admitted for hypoxia resulting from obesity hypoventilation syndrome. Laboratory tests showed normal levels of LH and FSH despite low testosterone and free testosterone levels. Moreover, thyroid stimulating hormone and prolactin levels were slightly elevated, although a euthyroid function was observed, and GH and IGF-1 levels were low. Endocrinological stimulation tests revealed hypogonadotropic hypogonadism and hypothalamic GH deficiency. Reduction in body weight by 35.3% resulted in the improvement of the IGF-1, thyroid stimulating hormone, and prolactin levels to the reference range, whereas the LH and FSH levels remained low, despite slight elevation. Levels of leptin, which suppresses the hypothalamus-gonadotroph-gonadal axis and upregulates thyrotropin-releasing hormone expression, decreased with weight loss. Furthermore, ghrelin, whose levels increase with weight loss, stimulates GH secretion. Thus, leptin and ghrelin could have contributed to the observed changes in the pituitary hormone profile after weight loss.

The GLP-1 receptor agonist exenatide reduces serum TSH by its effect on body weight in people with type 2 diabetes

OBJECTIVE

Glucagon-like peptide-1 receptor agonist (GLP-1 RA) therapy in patients with type 2 diabetes and obesity leads to a significant reduction in serum thyrotropin (TSH) levels but it is unclear whether this is related to weight loss and improvement in sensitivity to thyroid hormones (TH).

DESIGN, PATIENTS AND MEASUREMENTS

We prospectively analysed clinical and biochemical data in patients with type 2 diabetes and obesity who were commenced on the GLP-1 RA exenatide and followed them for 12 months. We assessed the relationship between changes in body weight and serum TSH and resistance to TH indices.

RESULTS

In 112 patients (mean age: 53.5 years, 43.8% female, mean body mass index: 39.8 kg/m2 ), 12 months of exenatide treatment was associated with a mean (95% CI) percent body weight loss of 6.5% (5.0%-8.1%) and change in serum TSH of -0.25 mU/L (-0.43 to -0.06). There was a significant negative and nonlinear relationship between change in serum TSH and percent body weight loss: -0.25 mU/L with 5%, -0.4 mU/L with 10% and -0.5 mU/L with 15%, respectively, whereas a rise in serum TSH of 0.5 mU/L was associated with 5% weight gain. There were no changes observed in serum FT4 levels with weight loss but a significant reduction in resistance to TH indices was noted.

CONCLUSIONS

Exenatide therapy reduces serum TSH levels and improves central sensitivity to TH action over 12 months via its effect on weight loss. The effectiveness of weight loss strategies, rather than TH replacement, should be investigated in individuals with obesity and mildly raised serum TSH levels.

Changes in Urinary Iodine Levels Following Bariatric Surgery

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Short-term Changes in Thyroid-Stimulating Hormone Level after Body Fat Reduction via Partial Meal Replacement

BACKGROUND

Serum thyroid-stimulating hormone (TSH) levels change during body weight reduction. However, the changes that occur during short-term body weight control interventions remain controversial. Thus, this study aimed to evaluate the changes in TSH levels according to body fat reduction.

METHODS

We performed a 3-month intervention study involving partial meal replacement. Forty-nine participants completed the study. Correlations between changes in TSH levels and other body composition parameters were determined. The subjects were divided into two groups according to their body fat reduction (>1 kg, n=20; <1 kg, n=29). The changes in metabolic parameters, including TSH levels, were compared. For significant values, a multivariate analysis was performed after adjustment to evaluate the relationship between TSH changes and body fat reduction.

RESULTS

The 3-month intervention caused favorable changes in body proportions and metabolic parameters. TSH levels changed significantly only after changes in total body fat, showing a partial correlation. Changes in TSH levels were significantly different between groups (P=0.014). Moreover, the change in TSH levels was significantly different after adjustment (P=0.012).

CONCLUSION

A body fat reduction, especially >1 kg, can reduce serum TSH concentrations in subjects with metabolic syndrome after short-term body weight intervention.

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.

Role of Leptin with hypothyroidism in Iraqi diabetic type 2 patients

In thyroid subjects, leptin hormone and thyroid-stimulating hormone levels connect; both are emphatically corresponding with adiposity. “Leptin hormone was essentially raised in the hypothyroid topic,” to levels like those seen in corpulent thyroid topic. This study aimed to determine leptin hormone levels, T3, T4, TSH, HbA1c %, FBG, lipid profile in diabetic and diabetic with hypothyroidism patients and compare the outcome with the healthy group. 90 samples were registered in this study with their ages ranging between (40 - 65) years that dole out into 3 groups as follows: thirty healthy groups (G1), thirty patients with diabetes (G2), and category three (G3) include diabetic patients and hypothyroidism as an associated disease. This study revealed a slightly significant elevated leptin in G3, contrasting to G2 and G1. Meantime no significant elevated spotted between G2 and G1. The conclusion could be from this investigation that leptin levels were changed in patients’ gatherings that might be utilized in checking and early analysis of thyroid dysfunction in these patients relying upon the significant connection for leptin chemical with T3, T4, and TSH.

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

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

The hypothalamus-pituitary-thyroid (HPT)-axis and its role in physiology and pathophysiology of other hypothalamus-pituitary functions

The hypothalamus-pituitary-thyroid axis is one of several hormone regulatory systems from the hypothalamus to the pituitary and ultimately to the peripheral target organs. The hypothalamus and the pituitary gland are in close anatomical proximity at the base of the brain and extended through the pituitary stalk to the sella turcica. The pituitary stalk allows passage of stimulatory and inhibitory hormones and other signal molecules. The target organs are placed in the periphery and function through stimulation/inhibition by the circulating pituitary hormones. The several hypothalamus-pituitary-target organ axis systems interact in very sophisticated and complicated ways and for many of them the interactive and integrated mechanisms are still not quite clear. The diagnosis of central hypothyroidism is complicated by itself but challenged further by concomitant affection of other hypothalamus-pituitary-hormone axes, the dysfunction of which influences the diagnosis of central hypothyroidism. Treatment of both the central hypothyroidism and the other hypothalamus-pituitary axes also influence the function of the others by complex mechanisms involving both central and peripheral mechanisms. Clinicians managing patients with neuroendocrine disorders should become aware of the strong integrative influence from each hypothalamus-pituitary-hormone axis on the physiology and pathophysiology of central hypothyroidism. As an aid in this direction the present review summarizes and highlights the importance of the hypothalamus-pituitary-thyroid axis, pitfalls in diagnosing central hypothyroidism, diagnosing/testing central hypothyroidism in relation to panhypopituitarism, pointing at interactions of the thyroid function with other pituitary hormones, as well as local hypothalamic neurotransmitters and gut-brain hormones. Furthermore, the treatment effect of each axis on the regulation of the others is described. Finally, these complicating aspects require stringent diagnostic testing, particularly in clinical settings with lower or at least altered à priori likelihood of hypopituitarism than in former obvious clinical patient presentations.

Interplay between metabolic and thyroid parameters in obese pubertal children. Does visceral adipose tissue make the first move?

Objectives: The mechanisms of obesity-associated thyroid dysfunction in children are incompletely deciphered. We aimed to evaluate whether visceral adipose tissue (VAT), insulin resistance (IR), inflammation, oxidative stress (OS) are involved in thyroid morpho-functional changes in pubertal obese children. Methods: We recruited 43 obese pubertal children without history of thyroid pathology. Metabolic and thyroid parameters (visceral fat thickness [VFT], waist/hip ratio [WHR], waist/height ratio [WHtR], insulin, glucose, liver parameters, thyroid stimulation hormone [TSH], free thyroxine [FT4], free triiodothyronine [FT3], thyroid and abdominal ultrasonography) were evaluated. Serum monocyte chemoattractant protein-1 (MCP-1) and malondialdehyde (MDA) levels were quantified as markers of inflammation and OS. Results: VFT correlated positively both with WHR (p= 0.034) and the presence of thyroid nodules (p= 0.036). WHR associated with TSH (p= 0.005), FT3/FT4 (p= 0.033) and was independently associated with FT3/FT4 increase (p< 0.001). HOMA-IR increased with visceral obesity (waist circumference, p= 0.001; WHR, p= 0.018; WHtR: p< 0.001), hepatic impairment (alanine aminotransferase, p= 0.019) and hepatic steatosis (HS; p= 0.013) and correlated positively with FT3/FT4 (p= 0.036). TSH was significantly higher in subjects with HS versus those without HS (p= 0.007) and logistic regression analysis identified TSH as a risk factor for HS (p= 0.014). MDA correlated positively with MCP-1 (p= 0.021). Conclusion: VAT and IR may be responsible for changes in thyroid parameters associated with obesity: elevated TSH, FT3/FT4 levels and increased prevalence of thyroid nodules. WHR was predictive of increased FT3/FT4. In obese children, there is an interdependent relationship between HS and thyroid function.

Antiobesity Effects of Adipose-Derived Stromal/Stem Cells in a Naturally Aged Mouse Model

OBJECTIVE

Adipose-derived stromal/stem cells (ASCs) have multilineage differentiation potential and functional properties, as well as applications for cell-based therapies in tissue repair and regeneration. However, there is a lack of evidence regarding the efficacy of ASCs as an antiobesity agent in aged organisms. This study aimed to clarify the effectiveness of ASCs at treating obesity using a naturally aged mouse model.

METHODS

Old (22 months) C57BL/6J mice with transplanted young-mice (2 months) donor ASCs were measured for weight change, biochemistry, cytokines, hormone secretion, cell senescence, lipid metabolism, and functional changes of ASCs.

RESULTS

The results indicated that old mice treated with ASCs showed antiaging and antiobesity effects such as significant loss of body and organ weight, improved stem cell plasticity, increased antioxidant capacity (superoxide dismutase and catalase), improved liver and kidney function, improved lipid metabolism, and increased hormone secretion (sex hormone-binding globulin, thyrotropin, and leptin). Treatment with ASCs decreased cell senescence and suppressed secretion of inflammatory agents (interleukin-6 and tumor necrosis factor alpha).

CONCLUSIONS

Traditional drugs used in the treatment of obesity have limitations and are unsuitable for the elderly. Based on the results, the future use of ASCs as primary antiaging and antiobesity agents is suggested because of their positive effects on aged animals.

Impaired Cardiovascular Function in Male Rats with Hypo- and Hyperthyroidism: Involvement of Imbalanced Nitric Oxide Synthase Levels

BACKGROUND AND OBJECTIVE

All three isoforms of nitric oxide (NO) synthase (NOS) are targets for thyroid hormones in the cardiovascular system. The aim of this study was to assess the effects of hypo- and hyperthyroidism on inducible (iNOS), endothelial (eNOS), and neural (nNOS) NOS levels in aorta and heart tissues of male rats.

METHODS

Rats were divided into control, hypothyroid, and hyperthyroid groups; hypo- and hyperthyroidism were induced by adding propylthiouracil (500 mg/L) and L-thyroxine (12 mg/L) to drinking water for a period of 21 days. On day 21, systolic blood pressure, heart rate, left ventricular developed pressure (LVDP), peak rate of positive and negative (±dp/dt) changes in left ventricular pressure as well as NO metabolites (NOx) and iNOS, eNOS, and nNOS protein levels in aorta and heart, were all measured.

RESULTS

Compared to controls, LVDP and ±dp/dt were lower in both hypo- and hyperthyroid rats. Compared to controls, heart rate and systolic blood pressure were lower in hypothyroid and higher in hyperthyroid rats. NOx levels in the heart of hypothyroid rats were lower (53%), whereas that in hyperthyroid rats were higher (56% and 40%) than controls. Compared to controls, hypothyroid rats had lower levels of eNOS, iNOS, and nNOS in the aorta (16%, 34%, and 15%, respectively) and lower iNOS and higher nNOS in heart tissue (27% and 46%). In hyperthyroid rats, eNOS levels were lower (54% and 30%) and iNOS were higher (63%, and 35%) in the aorta and heart while nNOS was lower in the aorta (18%).

CONCLUSION

Hypothyroidism increased while hyperthyroidism decreased the ratio of eNOS/iNOS in aorta and heart; these changes of NOS levels were associated with impaired cardiovascular function.

A matrix-assisted laser desorption/ionization imaging mass spectrometric approach to study weight-related changes within thyroid tissue

Obesity is associated with numerous comorbidities along with abnormalities of the endocrine system, more commonly manifesting as dysfunctions of the thyroid gland such as goiter. Changes in weight, especially an increase, could lead to an increase in the incidence of thyroid dysfunction; however, its pathophysiology remains to be elucidated. In the present study, we aimed to interrogate the changes in the protein distribution and abundance between the lean patients and patients with obesity thyroid tissue sections through utilizing this technique. The FFPE-fixed thyroid tissue blocks from the selected cases and controls were identified and targeted for matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) analysis. Patients in the 30 to 75 years age group and undergoing total thyroidectomy for benign thyroid disease were recruited. Patients with thyroid cancers, autoimmune disorders, and other inflammatory conditions were excluded from the study. The selected patients were divided into two groups according to their BMIs: lean (BMI < 25) and obese (BMI > 35). An initial trial set was used as a pilot study for the optimization of the MALDI IMS protocol that was next applied to the selected thyroid tissues. MALDI IMS data from all the samples were aligned and statistical analysis carried out by k-means and linear discriminant analysis (LDA) classification model using principle component analysis (PCA) results were evaluated between the two groups: controls (lean) and cases (obese). Receiver operator characteristic (ROC) curves were alternatively used to calculate the variability of the identified peptides. The discriminating peptides were also independently identified and related to their corresponding proteins by using liquid chromatography and tandem mass spectrometry (LC-MS/MS) analyses. Eight peptides mainly from thyroglobulin were found to be upregulated whereas 10 others were found to be downregulated in the lean compared to the obese group. Through this technique, we will be able to better understand the relationship between the disease entity and obesity.

Effects of sodium perchlorate and exogenous L-thyroxine on growth, development and leptin signaling pathway of Bufo gargarizans tadpoles during metamorphosis

Sodium perchlorate (NaClO₄) and exogenous L-thyroxine (T4), two kinds of endocrine-disrupting chemicals (EDCs), mainly affect the circulating thyroid hormones, which regulate the initiation and rate of metamorphosis in amphibian. The aim of this study is to evaluate the potential role of EDCs in regulating the development of tadpoles and leptin signaling pathway of liver during the metamorphosis of Bufo gargarizans. There was completely opposite result of average development stage of tadpoles and morphological parameters between the NaClO₄ and T4 exposure groups. Histological analysis revealed that NaClO₄ and T4 exposure both caused liver injury, such as the decreased size of hepatocytes, atrophy of nucleus, increased melanomacrophage centres and disappearance of hepatocyte membranes. In addition, the results of RT-qPCR revealed that NaClO₄ treatment significantly inhibited the transcript levels of genes related to thyroid hormone (D2, TRα and TRβ) and leptin signaling pathway (LepR, JAK1, JAK2, and TYK2), while there was an increase of mRNA expression of these genes in the liver of tadpoles administrated with T4 compared with control. This work lays an important foundation for assessing the risk of EDCs in relation to amphibian development during metamorphosis.

Greater effects of high- compared with moderate-intensity interval training on thyroid hormones in overweight/obese adolescent girls

OBJECTIVES

To investigate the effects of 12-week high-intensity- (HIIT) vs. moderate-intensity-interval training (MIIT) on thyroid stimulating hormone (TSH) and thyroxine (T4) and insulin-resistance in overweight/obese adolescent girls.

METHODS

Twenty four adolescent girls (age 16.5±1.36 yrs) were randomly allocated into three groups: (1) HIIT (2 blocks per session of 6-8 bouts of 30 s runs at 100-110% maximal aerobic speed (MAS), with 30 s active recovery between bouts at 50% MAS; n=8), (2) MIIT (2 blocks per session of 6-8 bouts of 30 s runs at 70-80% MAS, with 30 s active recovery between bouts at 50% MAS; n=8) and (3) control group (no exercise, n=8). Each training groups engaged in three sessions per week during three months. Anthropometric parameters, aerobic capacity, homeostasis model assessment index for insulin resistance (HOMA-IR) as well as plasma TSH and T4 levels were assessed in all subjects before- and after-training.

RESULTS

Following both training programs, body mass, body mass index Z-score, waist circumference and body fat decreased, while aerobic capacity increased. However, TSH and T4 concentrations decreased only after the HIIT (-30.47%, p<0.05, ES=1.42 and -12.86%, p<0.05, ES=1.18; respectively). The HOMA-IR decreased in both training groups (-26.25%, p<0.05, ES=1.87 for MIIT and -21.72%, p<0.05, ES=2.14 for HIIT).

CONCLUSION

Twelve weeks of HIIT was effective in reducing circulating TSH and T4 levels, unlike MIIT, in overweight/obese adolescent girls. These findings indicated that the stimulation of pituitary-thyroid function is more sensitive to training intensity than training duration. Further studies are needed to confirm this conclusion.

Thyroid dysfunction and its association with microvascular complications in patients with type 2 diabetes mellitus in south India

BACKGROUND AND AIMS

To study the prevalence of thyroid disorders and their association with microvascular complications among adult type 2 diabetes mellitus (T2DM) patients from south-coastal Andhra Pradesh, India METHODS: This cross-sectional study included 500 subjects with T2DM and was conducted in a tertiary health care center from south-coastal Andhra Pradesh. Participants previously diagnosed with thyroid disorders were excluded from the study.

RESULTS

Thyroid dysfunction was observed in 98 (19.6%) subjects of which subclinical hypothyroidism (n = 66, 13.2%) was the most common. Subclinical hypothyroidism (SCH) was more frequent in obese patients (16.2% vs 7.6%, p = 0.007) and metformin users (9.6% vs 18.7%, p = 0.0044). Diabetic retinopathy (27.3% vs 8.9%, p = 0.001) was significantly more frequent in SCH patients than euthyroid T2DM patients.

CONCLUSION

Among T2DM patients from south-coastal Andhra Pradesh the prevalence of thyroid dysfunction, especially that of SCH was high; SCH was more frequent among obese and nonmetformin users and was associated was associated with increased risk of diabetic retinopathy.

The roles of triiodothyronine and irisin in improving the lipid profile and directing the browning of human adipose subcutaneous cells

Triiodothyronine (T3) and irisin (I) can modulate metabolic status, increase heat production, and promote differentiation of white adipose tissue (WAT) into brown adipose tissue (BAT). Herein, human subcutaneous white adipocytes were treated with 10 nM T3 or 20 nM I for 24 h to evaluate intracellular lipid accumulation, triglyceride, and glycerol levels, oxidative stress, DNA damage, and protein levels of uncoupling protein 1 (UCP1), adiponectin, leptin, peroxisome proliferator-activated receptor gamma (PPARγ), and fibronectin type III domain-containing protein 5 (FNDC5). T3 and irisin improved UCP1 production, lipid profile, oxidative stress, and DNA damage. T3 elevated adiponectin and leptin levels with a concomitant decrease in PPARy and FNDC5 levels. However, irisin did not alter adipokine, PPARy, and FNDC5 levels. The results indicate that T3 may be used to increase leptin and adiponectin levels to improve insulin sensitivity, and irisin may be used to prevent obesity or maintain weight due to its impact on the lipid profile without altering adipokine levels.

Relationship Between Hormonal Mechanisms of Diabetes Mellitus and Hypothyroidism Post-Bariatric Surgery

BACKGROUND

Obesity, diabetes mellitus may be related to the health, the relationship and the physiological capacity of the production of thyroid hormones (TH), triiodothyronine (T3) and thyroxine (T4).

OBJECTIVES

The main aims of this review are to describe the relationship between obesity, appetite, weight management, hormonal mechanisms of diabetes mellitus and hypothyroidism post-bariatric surgery.

METHODOLOGY

An in-depth literature search was conducted to identify scientific studies, which analyzed the correlation between diabetes mellitus and hypothyroidism post-bariatric surgery.

RESULTS

Bariatric surgery decreases hypothyroidism, reduces the need for pharmacological action (such as levothyroxine), controls the weight and body fat and increases the sensitivity to leptin and insulin.

CONCLUSION

The reduction of the stomach and intestine by bariatric surgery is an evolutionary and beneficial action, because it may lead to a drastic decrease on numbers of conditions such as diabetes, obesity, hypothyroidism, and others. Thus, new studies should also focus on patients' post-operatory conditions, such as lifetime, regulation and functioning of organs after reduced nutrition, and consumption and delivery of nutrients to health maintenance.

Selenium and iodine in diabetes mellitus with a focus on the interplay and speciation of the elements

Diabetes mellitus is a chronic metabolic disease caused by insulin deficiency (type I) or dysfunction (type II). Diabetes is a threatening public health concern. It is considered as one of the priority non-communicable diseases, due to its high and increasing incidence, the associated healthcare costs, and threatening medical complications. Two trace elements selenium (Se) and iodine (I) were intensively discussed in the context of diabetic pathology and, possibly, etiology. It seems there is a multilayer involvement of these essential nutrients in glucose tolerance, energy metabolism, insulin signaling and resistance, which are mainly related to the antioxidant selenoenzymes and the thyroid hormones. Other factors might be related to (auto)immunity, protection against endoplasmic reticulum stress, and leptin signaling. The aim of the current review is to evaluate the current understanding of the role of selenium and iodine in diabetes with a focus on the biochemical interplay between the elements, their possible role as biomarkers, and their chemical speciation. Possible impacts from novel analytical techniques related to trace element speciation and isotopic analysis are outlined.

The brain-adipocyte-gut network: Linking obesity and depression subtypes

Major depressive disorder (MDD) and obesity are dominant and inter-related health burdens. Obesity is a risk factor for MDD, and there is evidence MDD increases risk of obesity. However, description of a bidirectional relationship between obesity and MDD is misleading, as closer examination reveals distinct unidirectional relationships in MDD subtypes. MDD is frequently associated with weight loss, although obesity promotes MDD. In contrast, MDD with atypical features (MDD-AF) is characterised by subsequent weight gain and obesity. The bases of these distinct associations remain to be detailed, with conflicting findings clouding interpretation. These associations can be viewed within a systems biology framework-the psycho-immune neuroendocrine (PINE) network shared between MDD and metabolic disorders. Shared PINE subsystem perturbations may underlie increased MDD in overweight and obese people (obesity-associated depression), while obesity in MDD-AF (depression-associated obesity) involves more complex interactions between behavioural and biomolecular changes. In the former, the chronic PINE dysfunction triggering MDD is augmented by obesity-dependent dysregulation in shared networks, including inflammatory, leptin-ghrelin, neuroendocrine, and gut microbiome systems, influenced by chronic image-associated psychological stress (particularly in younger or female patients). In MDD-AF, behavioural dysregulation, including hypersensitivity to interpersonal rejection, fundamentally underpins energy imbalance (involving hyperphagia, lethargy, hypersomnia), with evolving obesity exaggerating these drivers via positive feedback (and potentially augmenting PINE disruption). In both settings, sex and age are important determinants of outcome, associated with differences in emotional versus cognitive dysregulation. A systems biology approach is recommended for further research into the pathophysiological networks underlying MDD and linking depression and obesity.

Patients Treated for Hyperthyroidism Are at Increased Risk of Becoming Obese: Findings from a Large Prospective Secondary Care Cohort

Background: The most commonly reported symptom of hyperthyroidism is weight loss; successful treatment increases weight. Weight gain faced by patients with hyperthyroidism is widely considered a simple reaccumulation of premorbid weight, whereas many patients feel there is a significant weight "overshoot" attributable to the treatment. We aimed to establish if weight gain seen following treatment for hyperthyroidism represents replenishment of premorbid weight or "overshoot" beyond expected regain and, if there is excessive weight gain, whether this is associated with the applied treatment modality. Methods: We calculated the risk of becoming obese (body mass index [BMI] >30 kg/m²) following treatment for hyperthyroidism by comparing BMI of 1373 patients with overt hyperthyroidism seen in a secondary care setting with the age- and sex-matched background population (Health Survey for England, 2007-2009). Next, we investigated the effect of treatment with an antithyroid drug (ATD) alone in regard to ATD with radioactive iodine (¹³¹I) therapy. We modeled the longitudinal weight data in relation to the treatment pathway to thyroid function and the need for long-term thyroxine replacement. Results: During treatment of hyperthyroidism, men gained 8.0 kg (standard deviation ±7.5) and women 5.5 kg (±6.8). At discharge, there was a significantly increased risk of obesity in male (odds ratio = 1.7 [95% confidence interval 1.3-2.2], p < 0.001) and female (1.3, 1.2-1.5, p < 0.001) patients with hyperthyroidism compared with the background population. Treatment with ¹³¹I was associated with additional weight gain (0.6 kg, 0.4-0.8, p < 0.001), compared with ATD treatment alone. More weight gain was seen if serum thyrotropin (TSH) was markedly increased (TSH >10 mIU/L; 0.5 kg, 0.3-0.7, p < 0.001) or free thyroxine (fT4) was reduced (fT4 ≤ 10 pmol/L (0.8 ng/dL); 0.3 kg, 0.1-0.4, p < 0.001) during follow-up. Initiation of levothyroxine was associated with further weight gain (0.4 kg, 0.2-0.6, p < 0.001) and the predicted excess weight gain in ¹³¹I-induced hypothyroidism was 1.8 kg. Conclusions: Treatment for hyperthyroidism is associated with significant risks of becoming obese. ¹³¹I treatment and subsequent development of hypothyroidism were associated with small but significant amounts of excess weight gain compared with ATD alone. We advocate that the discussion over the weight "overshoot" risk forms part of the individualized treatment decision-making process.

Thyroid Dysfunction and Diabetes Mellitus: Two Closely Associated Disorders

Thyroid dysfunction and diabetes mellitus are closely linked. Several studies have documented the increased prevalence of thyroid disorders in patients with diabetes mellitus and vice versa. This review critically discusses the different underlying mechanisms linking type 1 and 2 diabetes and thyroid dysfunction to demonstrate that the association of these two common disorders is unlikely a simple coincidence. We assess the current state of knowledge on the central and peripheral control of thyroid hormone on food intake and glucose and lipid metabolism in target tissues (such as liver, white and brown adipose tissue, pancreatic β cells, and skeletal muscle) to explain the mechanism linking overt and subclinical hypothyroidism to type 2 diabetes and metabolic syndrome. We also elucidate the common susceptibility genes and the pathogenetic mechanisms contributing to the autoimmune mechanism involved in the onset of type 1 diabetes mellitus and autoimmune thyroid disorders. An untreated thyroid dysfunction can impair the metabolic control of diabetic patients, and this association can have important repercussions on the outcome of both of these disorders. Therefore, we offer recommendations for the diagnosis, management, and screening of thyroid disorders in patients with diabetes mellitus, including the treatment of diabetic patients planning a pregnancy. We also discuss the major causes of failure to achieve an optimal management of thyroid dysfunction in diabetic patients and provide recommendations for assessing and treating these disorders during therapy with antidiabetic drugs. An algorithm for a correct approach of these disorders when linked is also provided.

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.

Altered gene expression of hydrogen sulfide-producing enzymes in the liver and muscles tissues of hyperthyroid rats

Thyroid hormones have a role in the regulation of hydrogen sulfide (H₂ S) biosynthesis. In this study, we determined the effects of hyperthyroidism on H₂ S levels in various tissues and messenger RNA (mRNA) expression of cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3-MST) in the liver and muscles of the rat. Sixteen male Wistar rats were divided into the hyperthyroid and the control groups. Hyperthyroidism was induced by adding l-thyroxine (12 mg/L) to drinking water for a period of 21 days. H₂ S concentrations in serum, liver, aorta, heart, and soleus muscles, as well as mRNA expressions of CBS, CSE, and 3-MST in these tissues were measured at Day 21. Hyperthyroid rats had lower H₂ S levels in the serum compared with controls (14.7 ± 1.4 vs. 25.7 ± 1.6 µmol/L, p < 0.001). Compared with controls, hyperthyroid rats had lower levels of H₂ S in the aorta (89%), heart (80%), and soleus (103%) muscles, but higher levels in the liver (35%). Hyperthyroidism decreased the ratio of CBS/CSE mRNA expression in the liver and the CSE/CBS mRNA expression in the muscles by decreasing CBS levels in liver (34% cf. controls) and CSE levels in the aorta, heart, and soleus muscles (respectively, 51%, 7%, and 52% cf.). In addition, hyperthyroidism decreased the mRNA expression of 3-MST in the liver (51%) and aorta (33%), and increased it in the heart (300%) and soleus muscle (182%). In conclusion, hyperthyroidism increased H₂ S levels in the liver and decreased it in muscles; these effects are at least in part due to increases and decreases in expression of CSE in the liver and muscles, respectively. These data indicate an association between thyroid hormone status and gene expression of the H₂ S-producing enzymes in the rat.

Thyroid function during the first year of use of the injectable contraceptive depot medroxyprogesterone acetate

PURPOSE

The aim of the study was to evaluate thyroid function profile as a possible factor influencing weight and body composition variation in new users of depot medroxyprogesterone acetate (DMPA).

MATERIALS AND METHODS

A prospective, non-randomised, comparative study was conducted at the University of Campinas, Brazil. Women aged 18-40 years with a body mass index (BMI) less than 30 kg/m², normal oral glucose tolerance test, no known diseases, and using no medication, who opted to use DMPA were paired by age (±1 year) and BMI (±1 kg/m²) with women initiating copper intrauterine device (IUD) use. The main outcome measures were thyroid function profile, weight, and body composition, as measured by dual-energy X-ray absorptiometry. We used repeated measures ANOVA to perform comparisons between times and groups.

RESULTS

We evaluated 28 DMPA users and 24 IUD users who completed the 12-month follow-up. We observed that FT4 levels were higher at 12 months (compared to baseline) in the DMPA group (p < .0001) and that FT4/FT3 ratio had increased in both groups. Additionally, at 12 months, total body mass had increased around 2 kg and lean mass increased in the DMPA group compared to the IUD group; there was also an increase in weight, BMI, total body mass, and fat mass when compared to baseline.

CONCLUSIONS

No changes in thyroid function occurred that could explain the weight increase observed in DMPA users.

ASSOCIATIONS OF THYROID VOLUME AND FUNCTION WITH CHILDHOOD OBESITY

CONTEXT

The links between obesity and thyroid function or thyroid volume in children are still controversial with limited available data.

OBJECTIVE

This study aimed to examine thyroid function and volume in obese Turkish school-age children in comparison to normal-weight children.

DESIGN

Cross-sectional study.

SUBJECTS AND METHODS

One hundred obese children (47 boys, 53 girls; mean age 10.34±2.79 years) with a body mass index (BMI) above 95th percentile, and 100 normal-weight children (42 boys, 58 girls; 10.34±2.79 years) were included. The study parameters were BMI z score (Z-BMI), body surface area (BSA), thyroid volume, free thyroxine (fT4) and thyroid stimulating hormone (TSH) levels.

RESULTS

The mean TSH and fT4 levels did not show a significant difference between obese and normal-weight children (p>0.05). The mean thyroid volume was higher in obese children (6.46±5.84 and 4.64±1.44, respectively; p=0.043). fT4 correlated negatively with Z-BMI in both normal-weight and obese children (r=-0.285, p=0.004 and r=-0.289, p=0.004, respectively). Thyroid volume, on the other hand, correlated positively with Z-BMI, again in both normal-weight and obese children (r=0.657, p<0.001 and r=0.444, p<0.001, respectively). Similar associations were found for BSA.

CONCLUSIONS

Thyroid volume correlated positively and fT4 correlated negatively with Z-BMI and BSA, in both obese and normal-weight school-age children, whereas TSH appears to be independent of these parameters.

Reference Intervals of Thyroid Hormones and Correlation of BMI with Thyroid Function in Healthy Zhuang Ethnic Pregnant Women

Ethnic differences in the level of thyroid hormones exist among individuals. The American Thyroid Association (ATA) recommends that an institution or region should establish a specific thyroid hormone reference value for each stage of pregnancy. To date, a limited number of studies have reported the level of thyroid hormones in Chinese minorities, and the exact relationship between BMI and thyroid function in pregnant women is ill. This study was performed to establish trimester-specific reference ranges of thyroid hormones in Zhuang ethnic pregnant women and explore the role of body mass index (BMI) on thyroid function. A total of 3324 Zhuang ethnic health pregnant women were recruited in this Zhuang population-based retrospective cross-sectional study. The values of thyroid stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were determined by automatic chemiluminescence immunoassay analyzer. Multivariate linear regression and binary logistic regression were constructed to evaluate the influence of BMI on the thyroid function. The established reference intervals for the serum thyroid hormones in three trimesters were as follows: TSH, 0.02–3.28, 0.03–3.22, and 0.08-3.71 mIU/L; FT4, 10.57–19.76, 10.05–19.23, and 8.96–17.75 pmol/L; FT3, 3.51–5.64, 3.42–5.42, and 2.93–5.03 pmol/L. These values were markedly lower than those provided by the manufacturers for nonpregnant adults which can potentially result in 6.10% to 19.73% misclassification in Zhuang pregnant women. Moreover, BMI was positively correlated with isolated hypothyroxinemia (OR=1.081, 95% CI=1.007–1.161), while the correlation between the BMI and subclinical hypothyroidism was not statistically significant (OR=0.991, 95% CI=0.917–1.072). This is the first study focusing on the reference ranges of thyroid hormones in Guangxi Zhuang ethnic pregnant women, which will improve the care of them in the diagnosis and treatment. We also found that high BMI was positively associated with the risk of isolated hypothyroxinemia.

Adipocytokine correlations with thyroid function and autoimmunity in euthyroid sardinians

OBJECTIVE

Cytokines release by adipocytes could interact with TSH secretion. We evaluated the relationship between adipocytokines and TSH. We further tested for association of cytokines and thyroid autoimmunity.

METHODS

We conducted a cross-sectional study in a community-based sample including 5385 individuals (2964 female) with TSH within the reference range. Subjects who reported taking thyroid medications or drugs that alter thyroid function were excluded. TSH, FT4, adiponectin, leptin, antibody against thyroperoxidase and against thyroglobulin were measured. Linear and logistic regression models were used to test for association.

RESULTS

Females had higher adiponectin and leptin level and increased frequency of thyroid antibodies. In multiple regression analysis TSH was directly associated with leptin (β = 0.003, p = 0.001) and the presence of circulating antibody against thyroperoxidase (β = 0.315, p < 0.001), but negatively associated with age (β = -0.012, p < 0.001) and FT4 (β = -0.359, p < 0.001). Adiponectin, the presence of antibody against thyroglobulin and smoking habit were not associated with TSH levels (p = 0.223, p = 0.174 and p = 0.788, respectively). Logistic regression analysis revealed that higher adiponectin levels were associated with thyroid autoimmunity.

CONCLUSIONS

Leptin is positively associated with TSH levels in euthyroid individuals, suggesting an effect of the adipokine on TSH secretion. Our results support the hypothesis that the leptin and pituitary-thyroid axis might interact in the context of energy homeostasis. The effect of adiponectin on thyroid autoimmunity will require more studies.

Novel leptin OB3 peptide-induced signaling and progression in thyroid cancers: Comparison with leptin

Obesity results in increased secretion of cytokines from adipose tissue and is a risk factor for various cancers. Leptin is largely produced by adipose tissue and cancer cells. It induces cell proliferation and may serve to induce various cancers. OB3-leptin peptide (OB3) is a new class of functional leptin peptide. However, its mitogenic effect has not been determined. In the present study, because of a close link between leptin and the hypothalamic-pituitary-thyroid axis, OB3 was compared with leptin in different thyroid cancer cells for gene expression, proliferation and invasion. Neither agent stimulated cell proliferation. Leptin stimulated cell invasion, but reduced adhesion in anaplastic thyroid cancer cells. Activated ERK1/2 and STAT3 contributed to leptin-induced invasion. In contrast, OB3 did not affect expression of genes involved in proliferation and invasion. In vivo studies in the mouse showed that leptin, but not OB3, significantly increased circulating levels of thyrotropin (TSH), a growth factor for thyroid cancer. In summary, OB3 is a derivative of leptin that importantly lacks the mitogenic effects of leptin on thyroid cancer cells.

Thyroid Function in Korean Adolescents with Obesity: Results from the Korea National Health and Nutrition Examination Survey VI (2013-2015)

PURPOSE

In this study, we investigated the status of thyroid function and its association with metabolic risk factors in Korean adolescents.

METHODS

Among 2679 subjects aged 10-19 years who participated in the Korea National Health and Nutrition Examination Survey VI (2013-2015), 1067 adolescents (M = 559, F = 508) with available data on free T4 (FT4) and thyroid-stimulating hormone (TSH) were included. Study participants were classified into normal weight [body mass index (BMI) below 85th percentile, 80.7%], overweight (85th ≤ BMI< 95th percentile, 8.7%), and obesity (BMI ≥ 95th percentile, 10.6%).

RESULTS

With increasing levels of BMI category, the means of TSH increased (2.73 ± 0.06, 2.77 ± 0.02, and 3.24 ± 0.22 mIU/L, P = 0.031) and FT4 decreased (1.30 ± 0.01, 1.26 ± 0.02, and 1.25 ± 0.02 ng/mL, P = 0.001). Positive linear associations were observed between TSH and BMI z-score (P = 0.031), waist circumference (P = 0.013), waist-height ratio (P = 0.002), systolic blood pressure (P = 0.001), total cholesterol (P = 0.008), and triglyceride (P = 0.002) after adjusting for age and sex. With per-unit increase in TSH, the odds ratios of having abdominal obesity (OR = 1.18, 95% CI, 1.01-1.38) and triglyceride ≥ 150 mg/dL (OR = 1.18, 95% CI, 1.04-1.34) were significantly increased after adjusting for age, sex, and BMI.

CONCLUSIONS

In adolescents with obesity, TSH was higher and FT4 was lower than in adolescents with normal weight. Hyperthyrotropinemia was associated with abnormal metabolic risk factors including abdominal obesity and elevated triglyceride.

The Association of Triiodothyronine-to-Thyroxine Ratio with Body Mass Index in Obese Nigerian Children and Adolescents

The interest in the relationship between thyroid dysfunction and obesity is on the increase. This study compares the triiodothyronine-to-thyroxine (T3/T4) ratio in obese and lean children and adolescents, and correlates thyroid hormones with body mass index (BMI) in obese Nigerian children. It is a retrospective study of records of 76 obese children and adolescents with a BMI of 31.7 ± 0.1 kg/m² (26 males aged 10.9 ± 0.35 years, and 50 females aged 10.8 ± 0.4 years) that were referred to the laboratory for thyroid hormone evaluation because of their obese status. The controls were 20 age-matched non-obese apparently healthy subjects, with a mean age of 11.0 ± 0.47 years and a BMI of 20.2 ± 0.2 kg/m². Serum T3, T4, and thyroid stimulating hormone (TSH) were determined using ELECSYS 1010 auto-analyzer (Roche Diagnostics, Penzberg, Germany). The BMI (p < 0.001), T3 (p < 0.01), TSH (p < 0.001) and T3/T4 ratio (p < 0.001) were significantly higher in obese than non-obese children and adolescents. Triiodothyronine (r = 0.230; p < 0.05), TSH (r = 0.272; p < 0.02), and T3/T4 ratio (r = 0.232; p < 0.05) correlated positively with BMI in obese children and adolescents. The T3/T4 ratio (p < 0.005) was significantly higher in obese boys than obese girls. Serum T3, TSH, and T3/T4 ratio correlated positive with BMI in obese Nigerian children and adolescents. Since thyroid dysfunction represents a continuum from asymptomatic to clinical symptomatic disease, it is suggested that obese children be counseled on the need to maintain ideal BMI in order to avoid the risks associated with obesity.

Thyroid disorders in obese patients. Does insulin resistance make a difference?

OBJECTIVE

The aim of this study was to evaluate the association between insulin resistance and thyroid pathology in obese patients, and compare the results between insulin-resistant and noninsulin-resistant patients.

SUBJECTS AND METHODS

Obese/nondiabetic patients, aged 18-70 years, attending the outpatient endocrinology service for 2 years were consecutively included. We evaluated the patients' fasting plasma glucose, insulin, homeostasis model assessment of insulin resistance index (HOMA-IR), thyroid-stimulating hormone (TSH), free thyroxine (FT4), antithyroperoxidase antibodies (TPO-Ab), antithyroglobulin antibodies (Tg-Ab), and thyroid ultrasound.

RESULTS

We included 82 patients with a mean age 44.21 ± 12.67 years. The thyroid disorders encountered and their prevalences were: hypothyroidism (14.6%, 95% confidence interval [CI] 8.6-23.8%), hyperthyroidism (1.2%, 95% CI 2.0-6.6%), goiter (28.0%, 95% CI 19.5-3.6%), thyroid nodules (35.4%, 95% CI 25.9-46.2%), and Hashimoto's thyroiditis (32.9%, 95% CI 23.7-43.7%). HOMA-IR correlated positively with TSH levels (r = 0.24, p = 0.028), and this correlation remained after adjustment for body mass index (BMI), waist/hip ratio (WHR), serum cortisol, subcutaneous fat thickness (SFT), visceral fat thickness (VFT), triglycerides, γ-glutamyl transpeptidase (GGT), and alanine aminotransferase (ALT) in multivariate regression analysis (b = 0.207, 95% CI, 0.09-0.385, p = 0.023). TSH levels were significantly higher in patients with HOMA-IR ≥ 2.5 than in those with HOMA-IR < 2.5 (2.03 μIU/mL, interquartile range [IQR] 1.59-2.69 μIU/mL) versus 1.59 μIU/mL, IQR 0.94-2.26 μIU/mL, p = 0.023).

CONCLUSIONS

The most prevalent thyroid disorder in patients attending our endocrinology clinic for investigation of obesity was thyroid nodules. One in seven patients had hypothyroidism. Our findings suggest that TSH levels correlate with insulin resistance in obese patients.

Maternal thyroid function, prepregnancy obesity and gestational weight gain-The Generation R Study: A prospective cohort study

OBJECTIVE

Maternal prepregnancy obesity and excessive gestational weight gain are associated with pregnancy complications. Thyroid function is related to differences in body mass index (BMI) in adult populations. We examined the associations of maternal thyroid function in early pregnancy with maternal BMI and weight gain during pregnancy.

DESIGN AND METHODS

In a population-based prospective cohort study among 5726 mothers, we measured maternal TSH and FT4 levels at 13.5 weeks of gestation (95% range: 9.7-17.6 weeks). Maternal weight was assessed before pregnancy and in each trimester.

RESULTS

Higher maternal TSH levels were associated with higher prepregnancy BMI (difference: 0.18 kg/m² [95% CI: 0.01, 0.36] per SD increase in maternal TSH level) and higher total gestational weight gain (difference: 0.02 kg/wk [95% CI: 0.01, 0.03] per SD increase in maternal TSH level). Higher maternal FT4 levels were associated with lower prepregnancy BMI (difference: -0.44 kg/m² [95% CI: -0.63, -0.26] per SD increase in maternal FT4 level) and lower total gestational weight gain (difference: -0.01 kg/wk [95% CI: -0.02, -0.01] per SD increase in maternal FT4 level). The associations of maternal thyroid function with weight gain in early pregnancy were stronger than those with weight gain in mid and late-pregnancy. Maternal hypothyroidism was associated with higher prepregnancy BMI and early pregnancy weight gain, whereas opposite effects were observed for maternal hyperthyroidism (P<.05).

CONCLUSIONS

Higher maternal TSH level and lower FT4 level in early pregnancy are associated with higher prepregnancy BMI and higher gestational weight gain. Further studies are needed to explore maternal and foetal consequences.

Leptin OB3 peptide suppresses leptin-induced signaling and progression in ovarian cancer cells

BACKGROUND

Obesity and its comorbidities constitute a serious health burden worldwide. Leptin plays an important role in diet control; however, it has a stimulatory potential on cancer cell proliferation. The OB3 peptide, a synthetic peptide, was shown to be more active than leptin in regulating metabolism but with no mitogenic effects in cancer cells.

METHODS

In this study, we investigated the proliferative effects, gene expressions and signaling pathways modulated by leptin and OB3 in human ovarian cancer cells. In addition, an animal study was performed.

RESULTS

Leptin, but not OB3, induced the proliferation of ovarian cancer cells. Interestingly, OB3 blocked the leptin-induced proliferative effect when it was co-applied with leptin. Both leptin and OB3 activated the phosphatidylinositol-3-kinase (PI3K) signal transduction pathway. In addition, leptin stimulated the phosphorylation of signal transducer and activator of transcription-3 (STAT3) Tyr-705 as well as estrogen receptor (ER)α, and the expression of ERα-responsive genes. Interestingly, all leptin-induced signal activation and gene expressions were blocked by the co-incubation with OB3 and the inhibition of extracellular signal-regulated kinase (ERK)1/2. Coincidently, leptin, but not OB3, increased circulating levels of follicle-stimulating hormone (FSH) which is known to play important roles in the initiation and proliferation of ovarian cancer cells.

CONCLUSIONS

In summary, our findings suggest that the OB3 peptide may prevent leptin-induced ovarian cancer initiation and progression by disrupting leptin-induced proliferative signals via STAT3 phosphorylation and ERα activation. Therefore, the OB3 peptide is a potential anticancer agent that might be employed to prevent leptin-induced cancers in obese people.

Thyroid hormones in extreme longevity

The aim of the present review was to summarize knowledge about thyroid hormones (THs) and longevity. Longevity is a complex multifactorial phenomenon on which specific biological pathways, including hormonal networks involved in the regulation of homeostasis and survival, exert a strong impact. THs are the key responsible for growth, metabolism rate and energy expenditure, and help in maintaining cognition, bone and cardiovascular health. THs production and metabolism are fine tuned, and may help the organism to cope with a variety of environmental challenges. Experimental evidence suggests that hypothyroid state may favor longevity by reducing metabolism rate, oxidative stress and cell senescence. Data from human studies involving healthy subjects and centenarians seem to confirm this view, but THs changes observed in older patients affected by chronic diseases cannot be always interpreted as a protective adaptive mechanism aimed at reducing catabolism and prolonging survival. Medications, selected chronic diseases and multi-morbidity can interfere with thyroid function, and their impact is still to be elucidated.

Elevated thyroid stimulating hormone levels are associated with metabolic syndrome in a Chinese community-based population of euthyroid people aged 40 years and older

This study investigated whether high-normal thyrotropin (TSH) levels are associated with metabolic syndrome in euthyroid Chinese people≥40 years old. Clinical and metabolic factors were assessed in 2,356 subjects (40-77 years old) with TSH levels in the normal range (0.35-5.00 mU/L). Using 2.50 mU/L as the cut-off point of TSH level within the normal range, we divided subjects into the high-TSH (2.50-5.00 mU/L; n = 1,064) and low-TSH (0.35-2.50 mU/L; n = 11,292) group. The results showed that the mean levels of body mass index (BMI), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and fasting plasma glucose (FPG) were higher in the high-TSH group and TSH levels were significantly positively correlated with BMI, LDL-C, TC, and FPG. The prevalence of central obesity, hypertriglyceridemia, low high density lipoprotein cholesterol (HDL-C), and high FPG (>5.60 mmol/L) was significantly higher in females and subjects with high-TSH levels. Metabolic syndrome was also more prevalent in the high-TSH group. People over the age of 40 years with high-normal TSH levels had a 1.2-fold increased risk of metabolic syndrome, compared with those with low-normal TSH levels, after adjusting for age and gender. In conclusion, high normal TSH is a risk factor for metabolic syndrome in people≥40 years old.

Association of Serum Thyrotropin with Anthropometric Markers of Obesity in the General Population

BACKGROUND

Except from associations study with body weight, there are few longitudinal data regarding the association between thyroid function and anthropometric measurements such as waist circumference, waist-to-hip ratio, or waist-to height ratio.

OBJECTIVE

This study aimed to investigate the association of thyrotropin (TSH) at baseline with changes in different anthropometric markers between baseline and follow-up in the general population.

METHOD

Data were used from four population-based longitudinal cohort studies and one population-based cross-sectional study. A total of 16,902 (8204 males) subjects aged 20-95 years from the general population were studied. Body mass index, waist circumference, waist-to-hip ratio, and waist-to-height ratio were measured. Multivariable median regression models were calculated adjusting for the following covariates: age, sex, baseline value of the respective anthropometric marker, smoking status, follow-up-time period, and study site.

RESULTS

In cross-sectional analyses, serum TSH within the reference range was positively associated with waist circumference (β = 0.94 cm [confidence interval (CI) 0.56-1.32]) and waist-to-height-ratio (β = 0.029 [CI 0.017-0.042]). These associations were also present for the full range of TSH. In the longitudinal analyses, serum TSH at baseline was inversely associated with a five-year change of all considered anthropometric measures within the prior defined study-specific reference range, as well as in the full range of serum TSH.

CONCLUSION

High TSH serum levels were positively associated with current anthropometric markers, even in the study-specific reference ranges. In contrast, high TSH serum levels were associated with decreased anthropometric markers over a time span of approximately five years. Further research is needed to determine possible clinical implications as well as public health consequences of these findings.

Weight Changes in Patients with Differentiated Thyroid Carcinoma during Postoperative Long-Term Follow-up under Thyroid Stimulating Hormone Suppression

BACKGROUND

There are limited data about whether patients who receive initial treatment for differentiated thyroid cancer (DTC) gain or lose weight during long-term follow-up under thyroid stimulating hormone (TSH) suppression. This study was aimed to evaluate whether DTC patients under TSH suppression experience long-term weight gain after initial treatment. We also examined the impact of the radioactive iodine ablation therapy (RAIT) preparation method on changes of weight, comparing thyroid hormone withdrawal (THW) and recombinant human TSH (rhTSH).

METHODS

We retrospectively reviewed 700 DTC patients who underwent a total thyroidectomy followed by either RAIT and levothyroxine (T4) replacement or T4 replacement alone. The control group included 350 age-matched patients with benign thyroid nodules followed during same period. Anthropometric data were measured at baseline, 1 to 2 years, and 3 to 4 years after thyroidectomy. Comparisons were made between weight and body mass index (BMI) at baseline and follow-up.

RESULTS

Significant gains in weight and BMI were observed 3 to 4 years after initial treatment for female DTC but not in male patients. These gains among female DTC patients were also significant compared to age-matched control. Women in the THW group gained a significant amount of weight and BMI compared to baseline, while there was no increase in weight or BMI in the rhTSH group. There were no changes in weight and BMI in men according to RAIT preparation methods.

CONCLUSION

Female DTC patients showed significant gains in weight and BMI during long-term follow-up after initial treatment. These changes were seen only in patients who underwent THW for RAIT.

THYROID FUNCTION AND METABOLIC SYNDROME: A CROSS-SECTIONAL STUDY IN OBESE AND OVERWEIGHT PATIENTS

OBJECTIVE

Metabolic syndrome (MetS) is associated with increased risks of developing cardiovascular disease and type 2 diabetes. Thyroid dysfunction is also a known cardiovascular risk factor. In obese patients, serum thyroid-stimulating hormone (TSH) levels tend to be higher than in lean controls. The objective of this study was to assess potential associations between serum TSH levels and MetS as well as individual components of MetS.

METHODS

This was a cross-sectional observational study of obese and overweight patients seen for initial evaluation at the Boston Medical Center weight-management clinic between February 1, 2013 and February 1, 2014. Demographic, anthropometric, and laboratory data including serum TSH, insulin, glucose, hemoglobin A1c, and lipid levels were obtained from electronic medical records. Associations between serum TSH levels and presence of MetS and its components were assessed.

RESULTS

A total of 3,447 patients, 75.6% female and 38% African American, without known thyroid dysfunction, were included. Mean ± SD age was 46.74 ± 15.11 years, and mean ± SD body mass index was 36.06 ± 9.89 kg/m(2). Among 1,005 patients without missing data, the prevalence of MetS was 71.84%. In patients with MetS, the median serum TSH was 1.41 μIU/mL, compared with 1.36 μIU/mL in patients without MetS (P = .45). In multivariate models, there was no significant association between serum TSH levels and the presence of MetS, adjusting for age, sex, race, education, socioeconomic status, and smoking. There were also no significant associations between serum TSH and individual components of the MetS.

CONCLUSION

Serum TSH level does not appear to be a potentially modifiable risk factor for MetS in obese and overweight individuals.

Circulating Levels of Orexin-A, Nesfatin-1, Agouti-Related Peptide, and Neuropeptide Y in Patients with Hyperthyroidism

BACKGROUND

There is insufficient information about the appetite-related hormones orexin-A, nesfatin-1, agouti-related peptide (AgRP), and neuropeptide Y (NPY) in hyperthyroidism. The aim of the present study was to investigate the effects of hyperthyroidism on the basal metabolic rate (BMR) and energy intake, orexin-A, nesfatin-1, AgRP, NPY, and leptin levels in the circulation, and their relationship with each other and on appetite.

METHODS

In this prospective study, patients were evaluated in hyperthyroid and euthyroid states in comparison with healthy subjects. Twenty-one patients with overt hyperthyroidism and 33 healthy controls were included in the study.

RESULTS

Daily energy intake in the hyperthyroid state was found to be higher than that in the euthyroid state patient group (p=0.039). BMR was higher in hyperthyroid patients than the control group (p=0.018). Orexin-A was lower and nesfatin-1 was higher in hyperthyroid patients compared to the controls (p<0.001), whereas orexin-A increased and nesfatin-1 decreased after euthyroidism (p=0.003, p<0.001). No differences were found in the AgRP, NPY, and leptin levels between the hyperthyroid and euthyroid states and controls (p>0.05). Orexin-A correlated negatively with nesfatin-1 (p=0.042), BMR (p=0.013), free triiodothyronine (fT3; p<0.001), and free thyroxine (fT4; p<0.001) and positively with thyrotropin (TSH; p<0.001). Nesfatin-1 correlated negatively with orexin-A (p=0.042) and TSH (p<0.001) and positively with fT3 (p=0.005) and fT4 (p=0.001). In the regression analysis, "diagnosis of hyperthyroidism" was the main factor affecting orexin-A (p<0.001).

CONCLUSIONS

Although it seems that no relationship exists among orexin-A, nesfatin-1, and increased appetite in hyperthyroidism, the orexin-A and nesfatin-1 levels are markedly affected by hyperthyroidism.

Low-normal thyroid function and novel cardiometabolic biomarkers

The concept is emerging that low-normal thyroid function, i.e., either higher thyroid-stimulating hormone or lower free thyroxine levels within the euthyroid reference range, could contribute to the development of atherosclerotic cardiovascular disease. It is possible that adverse effects of low-normal thyroid function on cardiovascular outcome may be particularly relevant for specific populations, such as younger people and subjects with high cardiovascular risk. Low-normal thyroid function probably relates to modest increases in plasma total cholesterol, low density lipoprotein cholesterol, triglycerides and insulin resistance, but effects on high density lipoprotein (HDL) cholesterol and non-alcoholic fatty liver disease are inconsistent. Low-normal thyroid function may enhance plasma cholesteryl ester transfer, and contribute to an impaired ability of HDL to inhibit oxidative modification of LDL, reflecting pro-atherogenic alterations in lipoprotein metabolism and HDL function, respectively. Low-normal thyroid function also confers lower levels of bilirubin, a strong natural anti-oxidant. Remarkably, all these effects of low-normal thyroid functional status appear to be more outspoken in the context of chronic hyperglycemia and/or insulin resistance. Collectively, these data support the concept that low-normal thyroid function may adversely affect several processes which conceivably contribute to the pathogenesis of atherosclerotic cardiovascular disease, beyond effects on conventional lipoprotein measures.

Increased TSH in obesity: Evidence for a BMI-independent association with leptin

AIM

This study aimed to determine whether the association between thyroid-stimulating hormone (TSH) and body mass index (BMI) is related to leptin concentration in obese individuals.

METHODS

Plasma TSH and leptin assays were performed in 800 consecutive patients, hospitalized for a nutritional checkup, with a BMI ≥ 30 kg/m(2). Various anthropometric, hormonal and metabolic parameters, including age, weight, BMI, insulin, leptin and TSH, were measured or calculated. Univariate and multivariate regression analyses were performed to identify any significant relationships between these parameters. Also, characteristics of the patients in the lowest and highest quartiles of TSH distribution were compared.

RESULTS

TSH was positively correlated with both BMI and leptin. When multiple regression analysis was performed, TSH and leptin maintained a significant association independent of BMI. Patients in the fourth quartile of TSH distribution displayed higher BMI and higher leptin levels in comparison to the first quartile.

CONCLUSION

Our study has confirmed an increase in TSH in conjunction with BMI in obese subjects. This increase was correlated with leptin independently of BMI. It is hypothesized that the increase in TSH observed in obese subjects was the consequence of both fat mass accumulation and a positive energy-balance.

Obesity and thyroid cancer

Many studies have provided observational data on the association of obesity and thyroid cancers, but only few of them propose mechanisms that would permit a better understanding of the causal molecular mechanisms of this association. Considering that there is an increasing incidence of both obesity and thyroid cancers, we need to summarize and link recent studies in order to characterize and understand the contribution of obesity-related factors that might affect thyroid cancer development and progression. Adipose tissue is involved in many vital processes, including insulin sensitivity, angiogenesis, regulation of energy balance, activation of the complement system, and responses such as inflammation. Although these processes have their own molecular pathways, they involve the same molecules through which obesity and adipose tissue might exert their roles in carcinogenesis, not only affecting MAPK and PI3K or even insulin pathways, but also recruiting local inflammatory responses that could result in disease formation and progression. This review describes five important issues that might explain the link between excessive weight and thyroid cancer: thyroid hormones, insulin resistance, adipokines, inflammation, and sexual hormones.

Mechanisms in endocrinology: the crosstalk between thyroid gland and adipose tissue: signal integration in health and disease

Obesity and thyroid diseases are common disorders in the general population and they frequently occur in single individuals. Alongside a chance association, a direct relationship between 'thyroid and obesity' has been hypothesized. Thyroid hormone is an important determinant of energy expenditure and contributes to appetite regulation, while hormones and cytokines from the adipose tissue act on the CNS to inform on the quantity of energy stores. A continuous interaction between the thyroid hormone and regulatory mechanisms localized in adipose tissue and brain is important for human body weight control and maintenance of optimal energy balance. Whether obesity has a pathogenic role in thyroid disease remains largely a matter of investigation. This review highlights the complexity in the identification of thyroid hormone deficiency in obese patients. Regardless of the importance of treating subclinical and overt hypothyroidism, at present there is no evidence to recommend pharmacological correction of the isolated hyperthyrotropinemia often encountered in obese patients. While thyroid hormones are not indicated as anti-obesity drugs, preclinical studies suggest that thyromimetic drugs, by targeting selected receptors, might be useful in the treatment of obesity and dyslipidemia.

Thyroid function in adult Nigerians with metabolic syndrome

Introduction

Metabolic syndrome and thyroid dysfunction are two common disorders encountered in the metabolic clinic. Recently, there has been increased interest in the association between the two disorders because of the similarities between symptoms of hypothyroidism and components of the metabolic syndrome. While some reports suggest that metabolic syndrome is associated with subclinical hypothyroidism, this concept is largely under investigated in Nigerian adults with metabolic syndrome. The aim of this study is to determine the thyroid function status of adult Nigerians with metabolic syndrome and determine the association, if any, between metabolic syndrome and thyroid function.

Methods

This was a cross sectional study of one hundred and fifty adults, members of staff of the College of Medicine of the University of Lagos. The participants were recruited using a cluster random sampling method. The Ethical Research & Review Committee of the institution approved the study protocol and signed informed consent was obtained from the participants. The statistics was analysed using the IBM SPSS Software of version 19.0. The Student's t test, Chi square test and multivariate regression analysis were employed for the analysis. Statistical significance was set at p < 0.05.

Results

Thirty nine (twenty-six percent) of the study participants had metabolic syndrome and one hundred and eleven (seventy-four percent) of the study participants did not have metabolic syndrome, served as controls. Those who had metabolic syndrome group were significantly older (p = 0.03), metabolic syndrome was significantly associated with the female gender (p = 0.0002), higher systolic blood pressure (p = 0.0034), diastolic blood pressure (p = 0.0009), waist circumference (p < 0.0001), body mass index (p < 0.0001), waist-hip ratio (p = 0.003), fasting serum glucose (p = 0.0457) and free thyroxine (fT4) levels (p = 0.0496). Those with metabolic syndrome had significantly lower HDL (P = 0.004) and free triiodothyronine (fT3) levels (p = 0.037). There was no statistically significant difference in the thyroid stimulating hormone (TSH) levels between individuals with and without metabolic syndrome. Thirty-three percent of the metabolic syndrome cases had sick euthyroid syndrome (p= < 0.0001). In multivariate regression, waist circumference was significantly and inversely associated with the sick euthyroid syndrome (p = 0.011).

Conclusion

Metabolic syndrome is associated with the sick euthyroid syndrome in adult Nigerians. Abdominal obesity appears to be the link between metabolic syndrome and the sick euthyroid syndrome.

Molecular basis of thyrotropin and thyroid hormone action during implantation and early development

BACKGROUND

Implantation and early embryo development are finely regulated processes in which several molecules are involved. Evidence that thyroid hormones (TH: T4 and T3) might be part of this machinery is emerging. An increased demand for TH occurs during gestation, and any alteration in maternal thyroid physiology has significant implications for both maternal and fetal health. Not only overt but also subclinical hypothyroidism is associated with infertility as well as with obstetric complications, including disruptions and disorders of pregnancy, labor, delivery, and troubles in early neonatal life.

METHODS

We searched the PubMed and Google Scholar databases for articles related to TH action on ovary, endometrium, trophoblast maturation and embryo implantation. In addition, articles on the regulation of TH activity at cellular level have been reviewed. The findings are hereby summarized and critically discussed.

RESULTS

TH have been shown to influence endometrial, ovarian and placental physiology. TH receptors (TR) and thyrotropin (thyroid-stimulating hormone: TSH) receptors (TSHR) are widely expressed in the feto-maternal unit during implantation, and both the endometrium and the trophoblast might be influenced by TH either directly or through TH effects on the synthesis and activity of implantation-mediating molecules. Interestingly, due to the multiplicity of mechanisms involved in TH action (e.g. differential expression of TR isoforms, heterodimeric receptor partners, interacting cellular proteins, and regulating enzymes), the TH concentration in blood is not always predictive of their cellular availability and activity at both genomic and nongenomic level.

CONCLUSIONS

In addition to the known role of TH on the hormonal milieu of the ovarian follicle cycle, which is essential for a woman's fertility, evidence is emerging on the importance of TH signaling during implantation and early pregnancy. Based on recent observations, a local action of TH on female reproductive organs and the embryo during implantation appears to be crucial for a successful pregnancy. Furthermore, an imbalance in the spatio-temporal expression of factors involved in TH activity might induce early arrest of pregnancy in women considered as euthyroid, based on their hormonal blood concentration. In conclusion, alterations of the highly regulated local activity of TH may play a crucial, previously underestimated, role in early pregnancy and pregnancy loss. Further studies elucidating this topic should be encouraged.