Thyroid-adrenergic interactions: physiological and clinical implications

Epinephrine, Pregabalin, and Crizotinib as Three Medicines with Polish Implications over Three Last Centuries and in View of Three Different Drug Discovery Approaches

The discovery of epinephrine (adrenaline) and its subsequent implications in medicine owes significant contributions to Cybulski across different centuries, who, in 1894, was pivotal in identifying the adrenal medulla's role in blood pressure regulation and naming the active substance "nadnerczyna", known today as adrenaline. His work demonstrated the adrenal glands' critical function in the body's regulatory mechanisms beyond the nervous system. Cybulski's groundbreaking research laid foundational knowledge for future endocrinological studies and pharmaceutical advancements. In the late 20th century, Andruszkiewicz collaborated with Silverman at Northwestern University to develop pregabalin, the active ingredient in Lyrica. Their innovative synthesis of gamma-aminobutyric acid derivatives led to a significant advancement in treating epilepsy, neuropathic pain, and fibromyalgia. Andruszkiewicz's expertise in organic chemistry and enzymology was crucial in this collaborative effort, resulting in the successful development and commercialization of Lyrica. Additionally, Mroczkowski's leadership at Pfizer contributed to the development of crizotinib, a notable anaplastic lymphoma kinase and proto-oncogene 1 tyrosine-protein kinase inhibitor used to treat specific types of non-small cell lung cancer. Her work exemplifies the continuing influence of Polish researchers in pioneering drug discovery and advancing therapeutic treatments over the past three centuries. These contributions highlight Poland's significant role in global pharmaceutical innovations and medical research.

The Different Shades of Thermogenic Adipose Tissue

PURPOSE OF REVIEW

By providing a concise overview of adipose tissue types, elucidating the regulation of adipose thermogenic capacity in both physiological contexts and chronic wasting diseases (a protracted hypermetabolic state that precipitates sustained catabolism and consequent progressive corporeal atrophy), and most importantly, delving into the ongoing discourse regarding the role of adipose tissue thermogenic activation in chronic wasting diseases, this review aims to provide researchers with a comprehensive understanding of the field.

RECENT FINDINGS

Adipose tissue, traditionally classified as white, brown, and beige (brite) based on its thermogenic activity and potential, is intricately regulated by complex mechanisms in response to exercise or cold exposure. This regulation is adipose depot-specific and dependent on the duration of exposure. Excessive thermogenic activation of adipose tissue has been observed in chronic wasting diseases and has been considered a pathological factor that accelerates disease progression. However, this conclusion may be confounded by the detrimental effects of excessive lipolysis. Recent research also suggests that such activation may play a beneficial role in the early stages of chronic wasting disease and provide potential therapeutic effects. A more comprehensive understanding of the changes in adipose tissue thermogenesis under physiological and pathological conditions, as well as the underlying regulatory mechanisms, is essential for the development of novel interventions to improve health and prevent disease.

Generation of a mouse model of thyroid storm and preliminary investigation of the therapeutic effects of ghrelin

BACKGROUND

Thyroid storm (TS), a life-threatening condition that can damage multiple organs, has limited therapeutic options. Hypercytokinemia is a suggested background, but the pathological condition is unclear and there are no appropriate animal models. We aimed to develop a TS mouse model by administration of triiodothyronine and lipopolysaccharide, and then to examine the effects of ghrelin on this model.

METHODS

We evaluated the use of serum IL-6 levels as a representative marker of hypercytokinemia in patients with TS. To establish the mouse model, preliminary experiments were conducted to determine the non-lethal doses of triiodothyronine and lipopolysaccharide when administered individually. As a TS model, C57BL/6 mice were administered with triiodothyronine 1.0 mg/kg (subcutaneously, once daily for seven consecutive days) and lipopolysaccharide 0.5 mg/kg (intraperitoneally, on day 7) to develop a lethal model with approximately 30% survival on day 8. We assessed the survival ratio, mouse sepsis scores and blood biomarkers (IL-6, metanephrine, alanine aminotransferase) and evaluated the effects of ghrelin 300 µg/kg on these parameters in TS model.

RESULTS

Serum IL-6 was increased in patients with TS compared with those with Graves' disease as the diseased control (18.2 vs. 2.85 pg/mL, P < .05, n = 4 each). The dosage for the murine TS model was triiodothyronine 1.0 mg/kg and lipopolysaccharide 0.5 mg/kg. The TS model group had increased mouse sepsis score, serum IL-6, metanephrine and alanine aminotransferase. In this model, the ghrelin improved the survival rate to 66.7% (P < .01, vs. 0% [saline-treated group]) as well as the mouse sepsis score, and it decreased the serum IL-6 and metanephrine.

CONCLUSION

We established an animal model of TS that exhibits pathophysiological states similar to human TS with induction of serum IL-6 and other biomarkers by administration of T3 and LPS. The results suggest the potential effectiveness of ghrelin for TS in humans.

Clinical Efficacy of Beta-1 Selective Beta-Blockers Versus Propranolol in Patients With Thyroid Storm: A Retrospective Cohort Study

OBJECTIVES

Thyroid storm is the most severe manifestation of thyrotoxicosis. Beta-blockers are among the standard treatment regimens for this condition, with propranolol being the historically preferred option. However, 2016 guidelines issued by the Japan Thyroid Association and the Japan Endocrine Society recommend the use of beta-1 selective beta-blockers over nonselective beta-blockers, such as propranolol. Nevertheless, evidence supporting this recommendation is limited. Herein, we aimed to investigate the in-hospital mortality of patients with thyroid storms based on the choice of beta-blockers.

DESIGN

Retrospective cohort study.

SETTING

The Diagnosis Procedure Combination database, a national inpatient database in Japan.

PATIENTS

Patients hospitalized with thyroid storm between April 2010 and March 2022.

INTERVENTIONS

Propensity-score overlap weighting was performed to compare in-hospital mortality between patients who received beta-1 selective beta-blockers and those who received propranolol. Subgroup analysis was also conducted, considering the presence or absence of acute heart failure.

MEASUREMENTS AND MAIN RESULTS

Among the 2462 eligible patients, 1452 received beta-1 selective beta-blockers and 1010 received propranolol. The crude in-hospital mortality rates were 9.3% for the beta-1 selective beta-blocker group and 6.2% for the propranolol group. After adjusting for baseline variables, the use of beta-1 selective beta-blockers was not associated with lower in-hospital mortality (6.3% vs. 7.4%; odds ratio, 0.85; 95% CI, 0.57-1.26). Furthermore, no significant difference in in-hospital mortality was observed in patients with acute heart failure.

CONCLUSIONS

In patients with thyroid storm, the choice between beta-1 selective beta-blockers and propranolol did not affect in-hospital mortality, regardless of the presence of acute heart failure. Therefore, both beta-1 selective beta-blockers and propranolol can be regarded as viable treatment options for beta-blocker therapy in cases of thyroid storm, contingent upon the clinical context.

First presentation of Graves' thyroid storm complicated by catastrophic antiphospholipid antibody syndrome: A case report

Catastrophic antiphospholipid antibody syndrome is a rare and severe subtype of antiphospholipid syndrome with multisystemic organ failure due to thromboembolic events, resulting in high mortality rates. The association between catastrophic antiphospholipid antibody syndrome and autoimmune thyroid diseases is rarely reported in the literature. We report a case of a 35-year-old previously healthy female with Graves' thyroid storm, positive lupus antibodies, and probable catastrophic antiphospholipid antibody syndrome. Her hospital course was complicated by extensive venous thromboembolism, superior vena cava syndrome, thromboembolic strokes, and Takotsubo cardiomyopathy. Eventually, this led to an unfortunate death secondary to profound shock after 8 days despite emergent treatment. Our case report discusses the link between autoimmune thyroid disorders and catastrophic antiphospholipid antibody syndrome. We emphasize the difficulty in diagnosing catastrophic antiphospholipid antibody syndrome in extremely ill patients and stress the significance of considering it as a possible cause in thyrotoxicosis patients with multiple organ failure and hypercoagulability. Early recognition and prompt management are crucial in improving outcomes in these patients.

Hormonal basis of seasonal metabolic changes in mammalian species

Seasonal changes in external conditions (photoperiod, meteorological conditions, diet) cause adaptive changes in both energy and substrate metabolism in the animals of mammalian species. In summer, long days and a rich diet contribute to relative elevation in the levels of thyroid hormones (TH), but warmer weather lowers their levels. In winter, short days and a poor diet inhibit TH synthesis, but low temperatures increase their secretion. In addition, the results of our meta-analyses revealed a significant role of atmospheric pressure in circannual fluctuations of metabolic parameters in humans. The changes in photoperiod are generally viewed as a major factor contributing to seasonal rhythm regulation However, numerous data show that season-dependent metabolic changes in mammals could be also accounted for by meteorological factors and diet.

Takotsubo cardiomyopathy as the primary manifestation of decompensated Graves' disease

Takotsubo cardiomyopathy (TCM) is characterized by transient left ventricular dysfunction with apical ballooning, usually observed in postmenopausal women after a stressful event. We discuss a rare presentation of TCM induced by thyrotoxicosis secondary to Graves' disease. This case raises interesting questions about the pathogenesis, diagnosis, and management of TCM.

Learning objectives

1. To recognize hyperthyroidism as a possible etiology of takutsubo cardiomyopathy.2. To identify the effect of radioiodine contrast on diagnosis of some types of takutsubo cardiomyopathy.

Roles of β-adrenoceptor Subtypes and Therapeutics in Human Cardiovascular Disease: Heart Failure, Tachyarrhythmias and Other Cardiovascular Disorders

β-Adrenoceptors (β-ARs) provide an important therapeutic target for the treatment of cardiovascular disease. Three β-ARs, β1-AR, β2-AR, β3-AR are localized to the human heart. Activation of β1-AR and β2-ARs increases heart rate, force of contraction (inotropy) and consequently cardiac output to meet physiological demand. However, in disease, chronic over-activation of β1-AR is responsible for the progression of disease (e.g. heart failure) mediated by pathological hypertrophy, adverse remodelling and premature cell death. Furthermore, activation of β1-AR is critical in the pathogenesis of cardiac arrhythmias while activation of β2-AR directly influences blood pressure haemostasis. There is an increasing awareness of the contribution of β2-AR in cardiovascular disease, particularly arrhythmia generation. All β-blockers used therapeutically to treat cardiovascular disease block β1-AR with variable blockade of β2-AR depending on relative affinity for β1-AR vs β2-AR. Since the introduction of β-blockers into clinical practice in 1965, β-blockers with different properties have been trialled, used and evaluated, leading to better understanding of their therapeutic effects and tolerability in various cardiovascular conditions. β-Blockers with the property of intrinsic sympathomimetic activity (ISA), i.e. β-blockers that also activate the receptor, were used in the past for post-treatment of myocardial infarction and had limited use in heart failure. The β-blocker carvedilol continues to intrigue due to numerous properties that differentiate it from other β-blockers and is used successfully in the treatment of heart failure. The discovery of β3-AR in human heart created interest in the role of β3-AR in heart failure but has not resulted in therapeutics at this stage.

Atrioventricular block in patients with hyperthyroidism: a narrative review

Atrioventricular block (AVB) is a rare cardiac manifestation of hyperthyroidism (HTH). The scientific literature contains multiple reports of AVB in patients with HTH, ranging from subclinical to overt HTH and even thyroid storm. However, much remains unknown about the true prevalence, clinical course, optimal management, and outcomes of AVB in patients with HTH. Such patients are possibly overtreated with pacemakers because of a lack of understanding that AVB might be secondary to the hyperthyroid state and thus reversible. This narrative review discusses the pathophysiology of AVB in patients with HTH in the context of the available evidence.

Spexin may induce mitochondrial biogenesis in white and brown adipocytes via the hypothalamus-pituitary-thyroid (HPT) axis

AIM

The present study aimed to investigate the effect of the intracerebroventricular (icv) administration of spexin on the hypothalamus-pituitary-thyroid (HPT) axis (TRH, TSH, T4 and T3 hormones) and energy expenditure (PGC-1α and UCP1 genes) in white adipose (WAT) and brown adipose tissues (BAT) in rats. Furthermore, the study aimed to determine the effects of spexin on food-water consumption and body weight of rats.

MATERIAL AND METHOD

The study was conducted with 40 male rats that were divided into 4 groups: Control, Sham, Spexin 30 and Spexin 100 (n = 10). Spexin (1 μl/hour) was administered to rats other than those in the control group for 7 days with osmotic minipumps intracerebroventricularly, artificial cerebrospinal fluid (vehicle) was administered to the Sham group, and 30 nMol and 100 nMol spexin was infused to the Spexin 30 and Spexin 100 groups, respectively. Food-water consumption and body weight of the rats were monitored during the experiments. After the seven-day infusion, the rats were decapitated and serum TSH, fT4 and fT3 levels were determined with ELISA on rat blood samples. Also, TRH gene expression levels from the hypothalamus tissues and PGC-1α and UCP1 expression levels from WAT and BAT were determined by real-time PCR.

FINDINGS

It was determined that icv spexin infusion reduced daily food consumption and body weight without leading to a significant change in water consumption (p < 0.05). Icv spexin infusion significantly decreased serum TSH, and increased fT4 and fT3 levels when compared to control and sham groups (p < 0.05). Moreover, icv spexin infusion increased the TRH expressions in the hypothalamus tissues and PGC-1α UCP1 in the WAT and BAT (p < 0.05).

CONCLUSION

Icv Spexin infusion may have effects on food consumption and body weight as well as, thyroid hormones and energy metabolism.

Thyroid ultrasound pattern in primary hypothyroidism is similar to Graves' disease: a report of three cases

Ultrasound can identify important characteristics in primary hypothyroidism and diffuse hyperthyroidism (Graves' disease). Therefore, sonologists are actively investigating ultrasound criteria to differentiate between these two conditions. Nevertheless, practice shows the absence of such ultrasonic landmarks. For the first time in the literature, three cases of primary hypothyroidism have demonstrated an ultrasound pattern identical to that of Graves' disease. This pattern includes the presence of goiter, marked total hypoechogenicity of the parenchyma, significantly or moderately increased blood flow intensity ('thyroid inferno'), and elevated peak systolic velocity of the superior thyroid arteries. These signs are less common in hypothyroidism compared to hyperthyroidism. Diagnostic data suggest that the pathogeneses of primary hypothyroidism and Graves' disease share the same mechanisms, leading to similar thyroid ultrasound patterns. One of these shared mechanisms is presumably thyroid overstimulation by the autonomic nervous system, which is adequate to the body's hormonal requirements in hypothyroidism but excessive in hyperthyroidism.

Thyrotoxicosis

Hyperthyroidism is a diagnosis existing along a spectrum of severity. Patients present with a variety of signs and symptoms: tachycardia, elevated heart rate, anxiety, changes in mental status, gastrointestinal disturbances, and hyperthermia. Management of subclinical hyperthyroidism and thyrotoxicosis without thyroid storm is heavily dependent on outpatient evaluation. Thyroid storm is the most severe form of hyperthyroidism with the highest mortality. Management of thyroid storm follows a stepwise approach, with resuscitation and detection of the precipitating cause being paramount. Special attention should be paid to cardiac function in patients with thyroid storm before treatment, as these patients may develop cardiac collapse.

Data Analysis and Systematic Scoping Review on the Pathogenesis and Modalities of Treatment of Thyroid Storm Complicated with Myocardial Involvement and Shock

Thyroid storm (TS) is a rare and fatal endocrine emergency that occurs due to undiagnosed and inadequately treated hyperthyroidism after stressful conditions in patients with thyroid disorders. The objective of this systematic scoping review was to better understand the pathophysiology of TS and its complications, in terms of myocardial affection, tachyarrhythmia, and cardiogenic shock. In addition, we explored the pharmacological, mechanical, and surgical treatments for TS. We also evaluated the outcomes of TS according to sex and cardiac involvement. Additionally, analytical analysis was performed on the selected data. A literature review of peer-reviewed journals was carried out thoroughly using medical terms, MeSH on PubMed, Google Scholar, and combinations such as thyrotoxicosis-induced cardiomyopathy, thyroid storm, cardiogenic shock, myocardial infarction, endocrine emergency, Burch-Wartofsky score, extracorporeal circulatory support, and thyroidectomy. A total of 231 papers were eligible (2 retrospective studies, 5 case series, and 224 case reports) with a total of 256 TS patients with cardiac involvement between April 2003 and August 2023. All age groups, sexes, patients with TS-induced cardiomyopathy, non-atherosclerotic myocardial infarction, tachyarrhythmia, heart failure, shock, and different forms of treatment were discussed. Non-English language articles, cases without cardiac involvement, and cases in which treatment modalities were not specified were excluded. Female sex was predominant, with 154 female and 102 male patients. Approximately 82% of patients received beta-blockers (BBs), 16.3% were placed on extracorporeal membrane oxygenation (ECMO) support, 16.3% received therapeutic plasma exchange (TPE), and 13.8% underwent continuous renal replacement therapy (CRRT), continuous venovenous hemofiltration (CVVHD), or dialysis. Overall, 18 females and 16 males died. BB-induced circulatory collapse, acute renal failure, CRRT, and ventricular fibrillation were significantly associated with mortality. Awareness of TS and not only thyrotoxicosis is vital for timely and appropriate treatment. The early diagnosis and management of TS in cardiac settings, including pharmacological, mechanical, and surgical modalities, can save high-risk patients. Sex matters in the presentation, treatment, and mortality of this population. However, further large-scale, and well-designed studies are required.

High risk and low prevalence diseases: Thyroid storm

INTRODUCTION

Thyroid storm is a rare but serious condition that carries a high rate of morbidity and even mortality.

OBJECTIVE

This review highlights the pearls and pitfalls of thyroid storm, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Thyroid storm is a challenging condition to diagnose and manage in the ED. It is characterized by exaggerated signs and symptoms of thyrotoxicosis and evidence of multiorgan decompensation, usually occurring in the presence of an inciting trigger. Clinical features of thyroid storm may include fever, tachycardia, signs of congestive heart failure, vomiting/diarrhea, hepatic dysfunction, and central nervous system disturbance. There are several mimics including sympathomimetic overdose, substance use disorders, alcohol withdrawal, acute pulmonary edema, aortic dissection, heat stroke, serotonin syndrome, and sepsis/septic shock. Ultimately, the key to diagnosis is considering the disease. While laboratory assessment can assist, there is no single laboratory value that will establish a diagnosis of thyroid storm. Clinical criteria include the Burch-Wartofsky point scale and Japan Thyroid Association diagnostic criteria. ED treatment focuses on diagnosing and managing the trigger; resuscitation; administration of steroids, thionamides, iodine, and cholestyramine; and treatment of hyperthermia and agitation. Beta blockers should be administered in the absence of severe heart failure. The emergency clinician should be prepared for rapid clinical deterioration and employ a multidisciplinary approach to treatment that involves critical care and endocrinology specialists.

CONCLUSIONS

An understanding of thyroid storm can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Is beta-carotene consumption associated with thyroid hormone levels?

The thyroid hormones play a pivotal role in various physiological processes, including growth, metabolism regulation, and reproduction. While non-modifiable factors are known to impact thyroid function, such as genetics and age, nutritional factors are also important. Diets rich in selenium and iodine are conventionally acknowledged to be beneficial for the production and release of thyroid hormones. Recent studies have suggested a potential link between beta-carotene, a precursor to vitamin A (retinol), and thyroid function. Beta-carotene is known for its antioxidant properties and has been shown to play a role in the prevention of various clinical conditions such as cancer and cardiovascular and neurological diseases. However, its impact on thyroid function is still unclear. Some studies have suggested a positive association between beta-carotene levels and thyroid function, while others have found no significant effect. Conversely, the hormone produced by the thyroid gland, thyroxine, enhances the conversion of beta-carotene to retinol. Furthermore, vitamin A derivatives are being explored as potential therapeutic options for thyroid malignancies. In this review, we highlight the mechanisms through which beta-carotene/retinol and thyroid hormones interact and review the findings of clinical studies examining the association between beta-carotene consumption and thyroid hormone levels. Our review underscores the need for further research to clarify the relationship between beta-carotene and thyroid function.

Effect of thyroid hormone status on complete blood cell count-derived inflammatory biomarkers in patients with moderate-to-severe Graves' ophthalmopathy

PURPOSE

To evaluate the systemic inflammation in moderate-to-severe Graves' ophthalmopathy patients with abnormal thyroid function by using complete blood cell count-derived inflammatory biomarkers and compare to moderate-to-severe GO patients with regulated thyroid function and healthy controls. The second aim is to evaluate the relationship of complete blood cell count-derived inflammatory biomarkers with clinical findings in moderate-to-severe GO.

METHODS

In this retrospective study, 90 GO patients with abnormal thyroid function composed Group 1, 58 patients who had normal thyroid function for at least 3 months composed Group 2, and 50 healthy individuals composed Group 3. Demographic data, neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), mean platelet volume (MPV), and systemic immune-inflammatory index (SII) were evaluated.

RESULTS

There was no statistically significant difference between groups in terms of age, sex, and smoking habits (p > 0.05). There was a statistically significant difference in NLR (p = 0.011), MLR (p = 0.013), MPV (p < 0.001), and SII (p < 0.001) values among 3 groups. For NLR, MLR, and SII the highest values were detected in Group 1. MPV levels were higher in Group 3 than Groups 1 and 2 (p < 0.001). None of the hematological parameters were found to be a risk factor for any clinical severity findings of GO.

CONCLUSION

The higher levels of NLR, MLR, and SII levels may show systemic inflammation in GO patients with abnormal thyroid function, and this may have an impact on the clinical course of ophthalmopathy. These findings may suggest that cautious control of thyroid hormone levels is important in the management of GO.

Cerebral Sinus Vein Thrombosis and Gender: A Not Entirely Casual Relationship

Cerebral sinus venous thrombosis (CSVT) is a relatively rare acute disorder of cerebral circulation, but it can potentially be associated with serious sequelae and a poor prognosis. The neurological manifestations associated with it are often not adequately taken into consideration given the extreme variability and nuances of its clinical presentation and given the need for radiological methods suitable for this type of diagnosis. CSVT is usually more common in women, but so far there are little data available in the literature on sex-specific characteristics regarding this pathology. CSVT is the result of multiple conditions and is therefore to be considered a multifactorial disease where at least one risk factor is present in over 80% of cases. From the literature, we learn that congenital or acquired prothrombotic states are to be considered extremely associated with the occurrence of an acute episode of CSVT and its recurrences. It is, therefore, necessary to fully know the origins and natural history of CSVT, in order to implement the diagnostic and therapeutic pathways of these neurological manifestations. In this report, we summarize the main causes of CSVT considering the possible influence of gender, bearing in mind that most of the causes listed above are pathological conditions closely linked to the female sex.

Therapeutic Plasma Exchange for the Treatment of Hyperthyroidism: Approach to the Patient with Thyrotoxicosis or Antithyroid-Drugs Induced Agranulocytosis

Primary hyperthyroidism is an endocrine disorder characterized by excessive thyroid hormone synthesis and secretion by the thyroid gland. Clinical manifestations of hyperthyroidism can vary from subclinical to overt forms. In rare cases, hyperthyroidism may represent a clinical emergency, requiring admission to an intensive care unit due to an acute and severe exacerbation of thyrotoxicosis, known as a thyroid storm. First-line treatment of hyperthyroidism is almost always based on medical therapy (with thioamides, beta-adrenergic blocking agents, glucocorticoids), radioactive iodine or total thyroidectomy, tailored to the patient’s diagnosis. In cases of failure/intolerance/adverse events or contraindication to these therapies, as well as in life-threatening situations, including a thyroid storm, it is necessary to consider an alternative treatment with extracorporeal systems, such as therapeutic plasma exchange (TPE). This approach can promptly resolve severe conditions by removing circulating thyroid hormones. Here we described two different applications of TPE in clinical practice: the first case is an example of thyrotoxicosis due to amiodarone treatment, while the second one is an example of a severe adverse event to antithyroid drugs (agranulocytosis induced by methimazole).

Brown Adipose Tissue-A Translational Perspective

Brown adipose tissue (BAT) displays the unique capacity to generate heat through uncoupled oxidative phosphorylation that makes it a very attractive therapeutic target for cardiometabolic diseases. Here, we review BAT cellular metabolism, its regulation by the central nervous and endocrine systems and circulating metabolites, the plausible roles of this tissue in human thermoregulation, energy balance, and cardiometabolic disorders, and the current knowledge on its pharmacological stimulation in humans. The current definition and measurement of BAT in human studies relies almost exclusively on BAT glucose uptake from positron emission tomography with 18F-fluorodeoxiglucose, which can be dissociated from BAT thermogenic activity, as for example in insulin-resistant states. The most important energy substrate for BAT thermogenesis is its intracellular fatty acid content mobilized from sympathetic stimulation of intracellular triglyceride lipolysis. This lipolytic BAT response is intertwined with that of white adipose (WAT) and other metabolic tissues, and cannot be independently stimulated with the drugs tested thus far. BAT is an interesting and biologically plausible target that has yet to be fully and selectively activated to increase the body's thermogenic response and shift energy balance. The field of human BAT research is in need of methods able to directly, specifically, and reliably measure BAT thermogenic capacity while also tracking the related thermogenic responses in WAT and other tissues. Until this is achieved, uncertainty will remain about the role played by this fascinating tissue in human cardiometabolic diseases.

TSH levels within the normal range and risk of cardiovascular and all-cause mortality among individuals with diabetes

BACKGROUND

Evidence regarding thyroid-stimulating hormone (TSH) levels within the normal range and mortality in adults with diabetes is scarce. This study aimed to identify the association between TSH levels and cardiovascular disease (CVD) and all-cause mortality among euthyroid patients with diabetes.

METHODS

This prospective cohort study included 1830 adults with diabetes from the Third National Health and Nutrition Examination Survey III. Mortality outcomes were ascertained by linkage to National Death Index records through December 31, 2019. Participants were categorized by tertiles of TSH levels (low-normal, 0.39-1.30 mIU/L; medium-normal, 1.30-2.09 mIU/L; high-normal, 2.09-4.60 mIU/L). Multivariable Cox proportional hazards models were used to explore the association between TSH levels within the normal range and overall and CVD mortality. Furthermore, restricted cubic spline analyses were used to determine the nonlinear relationship between TSH levels and mortality.

RESULTS

During a median follow-up of 17.1 years, 1324 all-cause deaths occurred, including 525 deaths from CVD. After multivariate adjustment, a U-shaped relationship was observed between TSH levels in euthyroid status and all-cause or CVD mortality among patients with diabetes (both P < 0.05 for nonlinearity). Compared with participants with medium-normal TSH levels, those with high-normal TSH levels had a significantly higher risk of all-cause (hazard ratio, 1.31; 95% confidence interval, 1.07-1.61) and CVD (1.52; 1.08-2.12) mortality. Similarly, low-normal TSH levels also increased all-cause (1.39; 1.12-1.73) and CVD (1.69; 1.17-2.44) mortality risk. In stratum-specific analyses, we found that high-normal TSH levels were associated with higher mortality risk in younger (< 60 years) patients with diabetes but not in older (≥ 60 years) participants.

CONCLUSION

Low- and high-normal serum TSH levels were associated with increased all-cause and CVD mortality in euthyroid adults with diabetes. Further studies are needed to confirm the present observation in a wider population.

Association of Elevated Thyroid Stimulating Hormone with Atherosclerotic Cardiovascular Disease and Its Mortality in Elderly Community-Dwelling Chinese

Purpose

With increase of population aging, the prevalence of atherosclerotic cardiovascular disease (ASCVD) and elevated serum thyroid stimulating hormone (TSH) in elderly is increasing. High TSH level was reported to be associated with ASCVD and CVD mortality; however, few are studied in Chinese population, especially in the elderly. This study aimed to investigate the prevalence of elevated serum TSH and ASCVD in an elderly population of Chinese community and to explore the association between high serum TSH and ASCVD or CVD mortality.

Patients and Methods

We conducted a study involving 3814 adults who were at least 60 years of age. Questionnaires, physical examinations, and laboratory blood samples were collected in 2014, and a 78-months follow-up for cardiovascular and all-cause mortality was performed till December of 2020. Logistics regression was used to analyze the association between TSH and ASCVD. We used Cox models to assess the hazard ratios (HRs) for all-cause and CVD mortality across changes in serum TSH.

Results

In this study, the prevalence of the elevated serum TSH was 19.8%, and significantly higher in women than in men (24.5% vs 13.9%, p < 0.001). The prevalence of ASCVD was 21.7%. In logistics regression models, elevated TSH was associated with ASCVD after adjusting for the risk factors of ASCVD in people over the age of 70 years (adjusted OR 1.054, P = 0.014). After a follow-up of 6.5 years, total 441 (11.6%) all-cause death and 174 (4.6%) death of CVD were observed. In Cox regression model, no significant correlation was found between TSH and all-cause mortality or CVD mortality in the elderly population.

Conclusion

In the elderly population, there is high prevalence of elevated serum TSH and ASCVD. Elevated TSH seemed to be not associated with risk of all-cause or CVD mortality.

Cerebral venous sinus thrombosis caused by traumatic brain injury complicating thyroid storm: a case report and discussion

Introduction

Cerebral venous sinus thrombosis (CVST) is an uncommon cerebrovascular disease with diverse predisposing factors. We report a case of CVST caused by a thyroid storm induced by traumatic brain injury.

Case presentation

A 29-year-old male patient with a history of Graves’ disease with hyperthyroidism presented to our hospital with head trauma of cerebral contusion and laceration in both frontal lobes confirmed by admission CT scan. He received mannitol to lower intracranial pressure, haemostatic therapy, and antiepileptic treatment. Eight days later, he presented with signs of thyroid storms, such as tachycardia, hyperthermia, sweating and irritation, and his thyroid function tests revealed high levels of TPO-Ab, TR-Ab, TG-Ab, FT3 and FT4. Then, he entered a deep coma. His brain CT showed a thrombosis of multiple venous sinuses, along with the opening of peripheral collateral vessels, congestive infarction with haemorrhage and brain swelling. He regained consciousness after treatment with antithyroid drugs, anticoagulants, respiratory support and a regimen of sedation/analgesia. After a half-year follow-up, most of the patient’s blocked cerebral venous sinuses had been recanalized, but there were still some sequelae, such as an impaired fine motor performance of the right hand and verbal expression defects.

Conclusions

CVST can be induced by thyroid storms, and trauma-related thyroid storms can develop on the basis of hyperthyroidism. The purpose of this case report is to raise clinicians’ awareness and improve their ability to diagnose CVST early in patients with traumatic brain injury complicating thyroid storms to improve the neurological prognosis among similar patients.

Takotsubo cardiomyopathy in the setting of thyroid storm

A woman in her 50s with a background of chronic obstructive pulmonary disease secondary to smoking presented with intermittent chest tightness, dyspnoea and vomiting for 4 days. A presumed diagnosis of acute coronary syndrome (ACS) was made based on dynamic ischaemic ECG changes and elevation in high-sensitivity cardiac troponin T levels. She underwent emergent coronary angiography which demonstrated mild coronary artery disease with left ventriculography suggestive of mid-wall variant Takotsubo cardiomyopathy. Thyroid function tests performed to investigate sinus tachycardia were consistent with hyperthyroidism, and her thyroid-stimulating hormone receptor antibody was elevated. A diagnosis of thyroid storm was made in the setting of a newly diagnosed Graves’ disease and the patient was subsequently commenced on guideline-based therapy. This case demonstrates that Takotsubo cardiomyopathy, a mimic of ACS, is a possible complication of thyroid storm and therefore hyperthyroidism should be considered in the list of differentials in patients presenting with Takotsubo cardiomyopathy.

Hypothyroidism confers tolerance to cerebral malaria

The modulation of the host's metabolism to protect tissue from damage induces tolerance to infections increasing survival. Here, we examined the role of the thyroid hormones, key metabolic regulators, in the outcome of malaria. Hypothyroidism confers protection to experimental cerebral malaria by a disease tolerance mechanism. Hypothyroid mice display increased survival after infection with Plasmodium berghei ANKA, diminishing intracranial pressure and brain damage, without altering pathogen burden, blood-brain barrier disruption, or immune cell infiltration. This protection is reversed by treatment with a Sirtuin 1 inhibitor, while treatment of euthyroid mice with a Sirtuin 1 activator induces tolerance and reduces intracranial pressure and lethality. This indicates that thyroid hormones and Sirtuin 1 are previously unknown targets for cerebral malaria treatment, a major killer of children in endemic malaria areas.

Lytic cocktail: An effective method to alleviate severe burn induced hyper-metabolism through regulating white adipose tissue browning

Background

Browning of white adipose tissue is associated with elevated resting metabolic rates and is considered to be one of the indispensable causes of hypermetabolism in burn patients. Hypermetabolism means increased resting energy expenditure, raised body temperature and acute-phase proteins. Persistently elevated levels of circulating stress hormones have been reported to induce browning of subcutaneous white adipose tissue. The lytic cocktail is a combination of medicines pethidine, chlorpromazine, and promethazine that has been used clinically in sedation for the management of patients. As reported this sedative treatment can reduce the expression of catecholamines in major burn rats. Thus, in this paper we focused on the effects of lytic cocktail in the regulation of white adipose tissue browning and hypermetabolism and we further investigated the underlying mechanism.

Methods

A 30% total body surface area (TBSA) Ⅲ degree scald rat model was used for this study. The rats were randomly divided into a sham scald group, a scalding with immediate resuscitation group, and a group of scalding with immediate resuscitation and lytic cocktail treatment. The levels of norepinephrine and epinephrine in plasma were dynamically detected. Changes of the rat body weight and food intake were recorded and compared as indexes of metabolism responses after post-scalding. For the study of white adipose tissue browning, inguinal adipose tissue was used. Metabolic changes, while indicatives of white fat browning were measured by PET/CT. The expression of white adipose browning related proteins and the changes of mitochondria number were used to assess browning of inguinal adipose.

Results

The level of plasma catecholamines norepinephrine and epinephrine in the lytic cocktail-treated group was significantly lower than the other two groups. Morphology and PET/CT showed that the inguinal white adipose browning was inhibited in the lytic cocktail treated group, whereas scalding with immediate resuscitation group showed browning of white adipose. The number of mitochondria, the expressions of white adipose browning related proteins in the lytic cocktail group were also significantly lower than that of the group of scalding with immediate resuscitation.

Conclusion

By reducing expression of heat-related proteins, the application of lytic cocktail medicines inhibits the white adipose tissue browning, which suppresses hypermetabolism in scalded rats. The mechanism might be related to decreased expression levels of stress hormones induced by lytic cocktail. This research suggests that lytic cocktails may be an effective treatment for hypermetabolism after severe burn injury.

Prostate gland as a target organ of thyroid hormones: advances and controversies

Thyroid hormones (THs) are involved in the development and function of the male reproductive system, but their effects on the prostate have been poorly studied. This work reviews studies related to the interrelationship between the thyroid and the prostate. The information presented here is based upon bibliographic searches in PubMed using the following search terms: prostate combined with thyroid hormone or triiodothyronine, thyroxine, hypothyroidism, hyperthyroidism, or deiodinase. We identified and searched 49 articles directly related to the issue, and discarded studies related to endocrine disruptors. The number of publications has grown in the last 20 years, considering that one of the first studies was published in 1965. This review provides information based on in vitro studies, murine models, and clinical protocols in patients with thyroid disorders. Studies indicate that THs regulate different aspects of growth, metabolism, and prostate pathology, whose global effect depends on total and/or free concentrations of THs in serum, local bioavailability, and the endocrine androgen/thyronine context.

Thyroid Storm-induced Takotsubo Cardiomyopathy Presenting as Acute Chest Pain: A Case Report

Introduction

Stress-induced cardiomyopathy is a rare but serious cause of chest pain, which in recent studies has been shown to carry a similar in-hospital mortality to acute ST-elevation myocardial infarction. The pathophysiology of the disease is thought to be secondary to dysregulated catecholamine effects on myocardium.

Case Report

We present a case of a previously healthy female without known thyroid disease who presented to the emergency department for acute chest pain and was found to have thyroid storm-induced cardiomyopathy in a typical stress-induced cardiomyopathy pattern without evidence of coronary disease on catheterization.

Conclusion

Thyrotoxicosis can cause dysregulation of catecholamines and is a rare cause of stress-induced cardiomyopathy. It requires distinct therapies and should be considered by emergency physicians in the workup of acute chest pain with concern for stress-induced cardiomyopathy.

Pre-treatment Neutropenia in Children and Adolescents with Autoimmune Hyperthyroidism

OBJECTIVE

Neutropenia can occur in untreated autoimmune hyperthyroidism (AIH) or in association with treatment with the anti-thyroid drug, methimazole (MMI). Starting MMI in children and adolescents with AIH and pre-existing neutropenia could thus be worrisome. The aim was to describe the prevalence of neutropenia in pediatric AIH, prior to antithyroid drug therapy and to assess the effect of antithyroid drugs on neutrophil count.

METHODS

Patients with AIH attending a pediatric endocrinology clinic were retrospectively reviewed. Absolute neutrophil count (ANC) data at presentation and during anti-thyroid treatment for up to 24 weeks was collected. AIH was defined as elevated free thyroxine (fT4) or free tri-iodothyronine (fT3), suppressed thyroid stimulating hormone, and positive thyroid autoantibodies. Neutropenia was defined as ANC <1500 cells/μL.

RESULTS

Thirty-one patients (71% female) were included with a median interquartile range (IQR) age of 14.71 (11.89-17.10) years. Neither fT4 nor fT3 levels correlated with ANC at presentation (r_s=0.22, p=0.24 and r_s=0.13, p=0.54, respectively). 26/31 (84%) had normal baseline ANC. None developed neutropenia with thionamides. 5/31 (16%) had baseline neutropenia (median ANC 1,200/μL; IQR 874-1200). Four of these five started MMI at diagnosis while one was started on propranolol only but MMI was started one week later. All five normalized ANC within 24 weeks.

CONCLUSION

In this cohort, 16% of AIH patients had neutropenia at presentation, but this resolved in the short term and did not worsen with thionamides. Thionamides may be used with caution in these patients with close monitoring of blood counts.

Takotsubo syndrome: hyperthyroidism, pheochromocytoma, or both? A case report

Background

Takotsubo syndrome (TTS) is a transient left ventricular dysfunction usually with apical akinesia (classical pattern). Other less frequent variants have been described: the mid-ventricular pattern is characterized by hypokinesia of the mid-left ventricle and hypercontractile apical and basal segments; the inverted or basal pattern is characterized by basal and mid-ventricular segment hypokinesia or akinesia with preserved contractility or hypercontractility of apical segments and finally the focal pattern. There are also biventricular variants and forms with exclusive involvement of the right ventricle. There is a correlation between endocrine disorders and TTS, the one most frequently described is with pheochromocytoma. Catecholamine-mediated myocarditis, focal and diffuse myocardial fibrosis, and myocardial dysfunction are described in pheochromocytoma.

Case summary

We describe a case of a 69-year-old patient with a recent diagnosis of hypertension and Graves’ disease, hospitalized for persistent chest pain, hypertensive crisis, tachycardia, dyspnoea, and diaphoresis. Thyroid hormones, antibodies to TSH receptors, and hs-troponin I were increased. Electrocardiogram showed sinus tachycardia at 130 b.p.m., first-degree atrioventricular block, signs of left ventricular hypertrophy with inverted T wave in V4–V6. Echocardiogram demonstrated left ventricular apical and para-apical akinesia. Coronary angiography ruled out an obstructive coronary artery disease. Computed tomography angiogram aortic dissection ruled out aortic dissection but incidentally revealed a left adrenal mass compatible with a pheochromocytoma. Plasma and urinary metanephrines were increased. A TTS secondary to pheochromocytoma and hyperthyroidism was diagnosed. Pharmacological treatment included nitrates, urapidil and esmolol IV and methimazole at high doses. Type 2 multiple endocrine neoplasia has been excluded. After a complete haemodynamic stability on 20th day of hospitalization, the patient underwent an adrenalectomy.

Discussion

High levels of catecholamines in pheochromocytoma can lead to myocardial dysfunction. Similarly, an excess of thyroid hormones with up-regulation of adrenergic system can lead to myocardial dysfunction. These two conditions, if both present, define a high haemodynamic risk profile. How do catecholamines interact with the thyroid gland? The clinical case is of interest as a relationship has been hypothesized between the incretion of plasma catecholamines and Graves’ disease. We suppose an imbalance of the immune system with a predominance of the T helper-type 2 (Th2)-mediated response. Predominance of Th2-mediated immune response may induce humoral immunity causing Graves’ disease. In addition Th2 cytokines are strong inducers of M2 macrophages (alternatively activated) that are involved in autoimmune diseases, myocarditis, and myocardial fibrosis. Knowing the interaction between the cardiovascular system, immune response, and endocrine glands can help define the patient's risk class, possible complications, and follow-up.

Thyroid Hormones within the Normal Range and Cardiac Function in the General Population: The EPIPorto Study

BACKGROUND

Hypothyroidism and hyperthyroidism are associated with marked changes in cardiac structure and function. However, the association of thyroid function within the normal range with cardiac structure and function in the general population remains uncertain.

METHODS

Eight hundred thirty-five subjects aged ≥45 years from the EPIPorto cohort (evaluation between 2006 and 2008) were cross-sectionally analyzed. We excluded participants with TSH, free T4 (FT4), or free T3 (FT3) outside of the reference range or with self-reported cardiovascular or thyroid disease. Cardiac structure and function were evaluated by echocardiography. We used linear regression models unadjusted and adjusted for sex and age (model 1), and sex, age, BMI, diabetes, hypertension, and smoking (model 2). Nonlinear associations were assessed using restricted cubic splines.

RESULTS

The mean age was 61.5 years (SD 10.5); 61.1% of the patients were women. In the adjusted model 2, heart rate was positively associated with FT3; diastolic blood pressure was positively associated with TSH; LV end-diastolic and end-systolic volumes were inversely associated with TSH, and ejection fraction was nonlinearly associated with FT3, with higher ejection fractions near the limits of the reference range. Left ventricle (LV) posterior wall thickness was nonlinearly associated with FT4 in the adjusted model 1, with a greater thickness near the limits of the reference range. Regarding diastolic function, no significant associations were observed in adjusted models.

CONCLUSIONS

Thyroid function within the reference range was associated with heart rate, blood pressure, cardiac structure, and function. Increasing thyroid function (lower TSH, higher FT4, or higher FT3) was associated with a higher heart rate, a lower diastolic blood pressure, and larger LV volumes. LV wall thickness and ejection fraction had a U-shaped association with thyroid hormones.

A Blunted Sympathetic Function and an Enhanced Nitrergic Activity Contribute to Reduce Mesenteric Resistance in Hyperthyroidism

We aimed to determine whether an experimental model of hyperthyroidism could alter the function of sympathetic and nitrergic components of mesenteric innervation. For this purpose, male Wistar rats were divided into (1) control rats (CT) and (2) rats infused with L-Thyroxine (HT). Body weight gain and adipose tissue accumulation were lower in HT rats, while systolic blood pressure and citrate synthase activity in the soleus muscle were increased by HT. In segments from the superior mesenteric artery, the application of an electrical field stimulation (EFS) induced a vasoconstrictor response, which was lower in arteries from HT animals. The alpha-adrenoceptor antagonist phentolamine diminished EFS-induced vasoconstriction to a lower extent in HT arteries, while the purinergic receptor antagonist suramin reduced contractile response to EFS only in segments from CT. In line with this, noradrenaline release, tyrosine hydroxylase expression and activation and dopamine β hydroxylase expression were diminished in HT. The unspecific nitric oxide synthase (NOS) inhibitor L-NAME increased EFS-induced vasoconstriction more markedly in segments from HT rats. NO release was enhanced in HT, probably due to an enhancement in neuronal NOS activity, in which a hyperactivation of both PKC and PI3K-AKT signaling pathways might play a relevant role. In conclusion, perivascular mesenteric innervation might contribute to reduce the vascular resistance observed in hyperthyroidism.

Increased Incidence of Tinnitus Following a Hyperthyroidism Diagnosis: A Population-Based Longitudinal Study

BACKGROUND

An association between thyroid disease and tinnitus has been described previously but further longitudinal, population-based studies are limited.

OBJECTIVE

To investigate the incidence of tinnitus in patients with hyperthyroidism in a national sample, and to identify risk level and associated factors for tinnitus in hyperthyroidism patients.

DESIGN

Retrospective cohort study. Patient data were collected from the Longitudinal Health Insurance Database (LHID 2000), which includes national claims data of patient expenditures for admissions or ambulatory care from 1996 to 2011.

SETTING

Taiwan hospitals and clinics providing healthcare nationwide.

PARTICIPANTS

Patients aged 20 years and older with newly diagnosed hyperthyroidism (ICD-9-CM code 242) between 2000-2010 were selected as the study cohort. Hyperthyroidism patient cohort were identified from the LHID2000. Those with tinnitus history (ICD-9-CM code 388.3) before the index date (first hyperthyroidism diagnosis), younger than 20 years, and with incomplete demographic data were excluded. The non-hyperthyroidism cohort included patients with no history of hyperthyroidism and no documented tinnitus.

MAIN OUTCOMES AND MEASURES

Incidence of tinnitus was the primary outcome. Baseline demographic factors and comorbidities possibly associated with tinnitus, including age, sex, and comorbidities of hearing loss, vertigo, insomnia and anxiety, were retrieved from the LHID 2000. Patients were followed until end of 2011.

RESULTS

During the study period, 780 (4.9%) hyperthyroidism patients and 2007 (3.2%) non-hyperthyroidism controls developed tinnitus. Incidence rate of tinnitus in the hyperthyroidism cohort was significantly higher in hyperthyroidism cohort (7.86 vs. 5.05 per 1000 person-years) than that in non-hyperthyroidism cohort. A higher proportion of patients with hyperthyroidism had comorbid insomnia (45.1% vs. 30.9%) and anxiety (14.0% vs. 5.73%) than those without hyperthyroidism. After adjusting for age, gender and comorbidities (vertigo, insomnia, anxiety, hearing loss), hyperthyroidism patients had 1.38-fold higher risk of tinnitus (95% CI = 1.27-1.50) than those without hyperthyroidism.

CONCLUSIONS

This large population-based study suggests patients with diagnosed hyperthyroidism was more prone to develop tinnitus. Our findings suggest evaluation for comorbid vertigo, insomnia, anxiety and/or hearing loss may identify patients who are at high risk of developing tinnitus in patients with hyperthyroidism.

The paradoxical lean phenotype of hypothyroid mice is marked by increased adaptive thermogenesis in the skeletal muscle

Obesity is a major health problem worldwide, given its growing incidence and its association with a variety of comorbidities. Weight gain results from an increase in energy intake without a concomitant increase in energy expenditure. To combat the obesity epidemic, many studies have focused on the pathways underlying satiety and hunger signaling, while other studies have concentrated on the mechanisms involved in energy expenditure, most notably adaptive thermogenesis. Hypothyroidism in humans is typically associated with a decreased basal metabolic rate, lower energy expenditure, and weight gain. However, hypothyroid mouse models have been reported to have a leaner phenotype than euthyroid controls. To elucidate the mechanism underlying this phenomenon, we used a drug-free mouse model of hypothyroidism: mice lacking the sodium/iodide symporter (NIS), the plasma membrane protein that mediates active iodide uptake in the thyroid. In addition to being leaner than euthyroid mice, owing in part to reduced food intake, these hypothyroid mice show signs of compensatory up-regulation of the skeletal-muscle adaptive thermogenic marker sarcolipin, with an associated increase in fatty acid oxidation (FAO). Neither catecholamines nor thyroid-stimulating hormone (TSH) are responsible for sarcolipin expression or FAO stimulation; rather, thyroid hormones are likely to negatively regulate both processes in skeletal muscle. Our findings indicate that hypothyroidism in mice results in a variety of metabolic changes, which collectively lead to a leaner phenotype. A deeper understanding of these changes may make it possible to develop new strategies against obesity.

Migraine and tension headache comorbidity with hypothyroidism in Egypt

Background

Migraine, tension type headache (TTH), and hypothyroidism are clinical problems that affect patient daily activities and quality of life.

Objectives

The purpose of this study was to investigate the potential association between hypothyroidism in patients with migraine and TTH.

Patients and methods

Two hundred and twelve patients with migraine and TTH and one hundred control subjects underwent clinical evaluation, assessment of thyroid hormones, and thyroid ultrasound.

Results

Subclinical and overt hypothyroidism were significantly higher in patients with migraine and TTH (P = 0.001) than control subjects. Patients with migraine and TTH showed significantly more abnormal thyroid gland morphology than healthy control (P = 0.027). Hypothyroidism is significantly expressed in chronic TTH more than TTH with infrequent or frequent TTH (P = 0.009).

Conclusions

Patients having migraine and TTH more prone to develop hypothyroidism when compared with control group. Also patients with chronic TTH are susceptible to develop hypothyroidism (either subclinical or overt) when compared with patients having frequent or infrequent TTH.

Genomic and Non-Genomic Mechanisms of Action of Thyroid Hormones and Their Catabolite 3,5-Diiodo-L-Thyronine in Mammals

Since the realization that the cellular homologs of a gene found in the retrovirus that contributes to erythroblastosis in birds (v-erbA), i.e. the proto-oncogene c-erbA encodes the nuclear receptors for thyroid hormones (THs), most of the interest for THs focalized on their ability to control gene transcription. It was found, indeed, that, by regulating gene expression in many tissues, these hormones could mediate critical events both in development and in adult organisms. Among their effects, much attention was given to their ability to increase energy expenditure, and they were early proposed as anti-obesity drugs. However, their clinical use has been strongly challenged by the concomitant onset of toxic effects, especially on the heart. Notably, it has been clearly demonstrated that, besides their direct action on transcription (genomic effects), THs also have non-genomic effects, mediated by cell membrane and/or mitochondrial binding sites, and sometimes triggered by their endogenous catabolites. Among these latter molecules, 3,5-diiodo-L-thyronine (3,5-T2) has been attracting increasing interest because some of its metabolic effects are similar to those induced by T3, but it seems to be safer. The main target of 3,5-T2 appears to be the mitochondria, and it has been hypothesized that, by acting mainly on mitochondrial function and oxidative stress, 3,5-T2 might prevent and revert tissue damages and hepatic steatosis induced by a hyper-lipid diet, while concomitantly reducing the circulating levels of low density lipoproteins (LDL) and triglycerides. Besides a summary concerning general metabolism of THs, as well as their genomic and non-genomic effects, herein we will discuss resistance to THs and the possible mechanisms of action of 3,5-T2, also in relation to its possible clinical use as a drug.

Non-thyroidal illness syndrome, the hidden player in the septic shock induced myocardial contractile depression

Septic shock causes high mortality in hospitalized patients, especially in those that develop myocardial dysfunction as an early complication. The myocardial dysfunction of septic shock is characterized by a decrease in ventricular relaxation (diastolic dysfunction) and reduced ventricular ejection fraction (systolic dysfunction). Most patients with septic shock have low serum thyroid hormone levels, a condition known as non-thyroidal illness syndrome. Thyroid hormones sustain myocardial contractility and energy metabolism. Septic shock non-thyroidal illness syndrome causes myocardial hypothyroidism, and hypothyroidism causes myocardial dysfunction that resembles the myocardial depression of septic shock. We hypothesize that the myocardial hypothyroidism that occurs during septic shock has a causal role in the pathogenesis of septic shock-induced myocardial dysfunction. Thyroid hormones regulate the calcium cycle, the phenotype of contractile proteins, adrenergic response, and fatty acid transport and oxidation in the cardiomyocytes. Therefore, the administration of levothyroxine and liothyronine to normalize thyroid hormones level within the myocardium will improve the myocardial function. The hypothesis will be tested in humans with septic shock by performing a prospective, randomized, placebo-controlled study to compare the effect of thyroid hormone administration with placebo on myocardial function. The proposed hypothesis challenges the idea that non-thyroidal illness syndrome is a beneficial response of the thyroid hormone axis to illness and that thyroid hormone replacement is detrimental. The administration of thyroid hormone in order to prevent and reverse myocardial hypothyroidism during septic shock is a new theoretical concept on thyroid hormone metabolism and action at the tissue level during non-thyroidal illness syndrome. If the hypothesis is correct, clinicians should consider cardiac hypothyroidism as a central player in myocardial dysfunction caused by sepsis. Thyroid hormone replacement should be incorporated into the armamentarium of septic shock treatment.

Inuit metabolism revisited: what drove the selective sweep of CPT1a L479?

This article reassesses historical studies of Inuit metabolism in light of recent developments in evolutionary genetics. It discusses the possible selective advantage of a variant of CPT1a, which encodes the rate limiting enzyme in hepatic fatty acid oxidation. The L479 variant of CPT1a underwent one of the strongest known selective sweeps in human history and is specific to Inuit and Yu'pik populations. Recent hypotheses predict that this variant may have been selected in response to possible detrimental effects of chronic ketosis in communities with very low carbohydrate consumption. Assessing these hypotheses alongside several alternative explanations of the selective sweep, this article challenges the notion that the selection of L479 is linked to predicted detrimental effects of ketosis. Bringing together for the first time data from biochemical, metabolic, and physiological studies inside and outside the Inuit sphere, it aims to provide a broader interpretative framework and a more comprehensive way to understand the selective sweep. It suggests that L479 may have provided a selective advantage in glucose conservation as part of a metabolic adaptation to very low carbohydrate and high protein consumption, but not necessarily a ketogenic state, in an extremely cold environment. A high intake of n-3 fatty acids may be linked to selection through the mitigation of a detrimental effect of the mutation that arises in the fasted state. The implications of these conclusions for our broader understanding of very low carbohydrate metabolism, and for dietary recommendations for Inuit and non-Inuit populations, are discussed.

Thyroid hormone receptor: A new player in epinephrine-induced larval metamorphosis of the hard-shelled mussel

Many marine invertebrate larvae undergo a dramatic morphological and physiological transition from a planktonic larva to a benthic juvenile. The mechanisms of this metamorphosis in bivalves are mainly unknown. The recent identification in bivalves of a thyroid hormone receptor (TR) gene raises the possibility that as occurs in vertebrate metamorphosis, TRs regulate this developmental process. An evolutionary study of TR receptors revealed they are ubiquitous in the molluscs. Knock-down of the TR gene in pediveliger larvae of the hard-shelled mussel, Mytilus coruscus (Mc), using electroporation of siRNA significantly (p < 0.01) reduced TR gene expression. TR gene knock-down decreased pediveliger larval metamorphosis by 54% and was associated with a significant (p < 0.01) reduction in viability compared to control larvae. The TR in the hard-shelled mussel appears to be an essential regulatory factor for the successful epinephrine-induced metamorphosis of the pediveliger larvae to post-larvae. It is hypothesised that the knock-down of TR by siRNA transfection affects the "competence" of pediveliger larvae for the metamorphic transition by reducing their ability to respond to the inducer. The involvement of TR in the epinephrine-induced metamorphosis of a mollusc, the hard-shelled mussel, suggests the role of TR in this process probably emerged early during evolution.

Functional Status of Hypothalamic-Pituitary-Thyroid and Hypothalamic-Pituitary-Adrenal Axes in Hospitalized Schizophrenics in Shanghai

OBJECTIVE

Neuroendocrine dysfunction is related to the pathogenesis of mental disorders, but conclusions from clinical research lack consistency. We aimed to investigate the neuroendocrinal pathophysiology and its correlation with clinical symptoms in patients with schizophrenia.

METHODS

The present cross-sectional study included 486 inpatients with schizophrenia admitted at a psychiatric hospital in Shanghai within one year, and 154 healthy controls (HC) matched on age and gender. The serum hemoconcentrations of thyroid-stimulating hormone (TSH), total triiodothyronine (TT3), total thyroxine (TT4), free triiodothyronine (FT3), free thyroxine (FT4), adrenocorticotrophic hormone (ACTH), and cortisol (COR) were measured via electrochemical luminescence immunoassay. Pathophysiological conversions of neuroendocrine were then associated with gender, age, age at onset, antipsychotic treatment using hierarchical multiple linear regression.

RESULTS

When compared to HC, the schizophrenia group showed elevated ACTH and COR levels and decreased TT3 and TT4 levels (p's < 0.05). First-episode patients showed lower TSH and higher FT3 and FT4 (p's < 0.05) compared to recurrent patients. Female patients showed higher TSH and lower TT3, FT3, and ACTH levels (p's < 0.05) compared to males. We observed the area under the curve (AUC) of the predictive model to distinguish between schizophrenia and HC to be 0.737 among total samples and between first-episode and recurrent schizophrenia to be 0.890 among subgroups.

CONCLUSIONS

Decreased TT3 and TT4 and elevated ACTH and COR levels appear to be associated with schizophrenia symptoms. The chronic recurrent trait of schizophrenia may cause long-term effects on FT3 and FT4 while changes in thyroid, and adrenal function as a result of mental disorder varied with gender. The pathophysiological parameters provide fair to good accuracy of these models.

Thyroid hormones and modulation of diastolic function: a promising target for heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome with high mortality for which there is no proven therapy to improve its prognosis. Thyroid dysfunction is common in heart failure (HF) and is associated with worse prognosis. In this review, we discuss the cardiovascular effects of thyroid hormones, the pathophysiology of HFpEF, the prognostic impact of thyroid function, and the potential of thyroid hormones for treatment of HFpEF. Thyroid hormones have a central role in cardiovascular homeostasis, improving cardiac function through genomic and non-genomic mechanisms. Both overt and subclinical hypothyroidism are associated with increased risk of HF. Even when plasmatic thyroid hormones levels are normal, patients with HF may have local cardiac hypothyroidism due to upregulation of type 3 iodothyronine deiodinase. Thyroid hormones improve several pathophysiological mechanisms of HFpEF, including diastolic dysfunction and extra-cardiac abnormalities. Supplementation with thyroid hormones (levothyroxine and/or liothyronine), modulation of deiodinase activity, and heart-specific thyroid receptor agonists are potential therapeutic approaches for the treatment of HFpEF. Further preclinical and clinical studies are needed to clarify the role of thyroid hormones in the treatment of HFpEF.

Novel Aspects of White Adipose Tissue Browning by Thyroid Hormones

Thyroid hormones are essential for the full thermogenic capacity of brown adipose tissue. The thermogenic response of brown adipocytes to thyroid hormones is resulting from the synergistic interaction of thyroid hormones with the sympathetic nervous system. In recent years, evidence has been provided that thyroid hormones also induce the browning of white adipose tissues. This review will provide a brief overview about the recent findings regarding the effects of thyroid hormones on adipose tissue thermogenesis including central and peripheral regulation of white adipose tissue browning.

Structural brain changes in hyperthyroid Graves' disease: protocol for an ongoing longitudinal, case-controlled study in Göteborg, Sweden-the CogThy project

INTRODUCTION

Cognitive impairment and reduced well-being are common manifestations of Graves' disease (GD). These symptoms are not only prevalent during the active phase of the disease but also often prevail for a long time after hyperthyroidism is considered cured. The pathogenic mechanisms involved in these brain-derived symptoms are currently unknown. The overall aim of the CogThy study is to identify the mechanism behind cognitive impairment to be able to recognise GD patients at risk.

METHODS AND ANALYSIS

The study is a longitudinal, single-centre, case-controlled study conducted in Göteborg, Sweden on premenopausal women with newly diagnosed GD. The subjects are examined: at referral, at inclusion and then every 3.25 months until 15 months. Examinations include: laboratory measurements; eye evaluation; neuropsychiatric and neuropsychological testing; structural MRI of the whole brain, orbits and medial temporal lobe structures; functional near-infrared spectroscopy of the cerebral prefrontal cortex and self-assessed quality of life questionnaires. The primary outcome measure is the change in medial temporal lobe structure volume. Secondary outcome measures include neuropsychological, neuropsychiatric, hormonal and autoantibody variables. The study opened for inclusion in September 2012 and close for inclusion in October 2019. It will provide novel information on the effect of GD on medial temporal lobe structures and cerebral cortex functionality as well as whether these changes are associated with cognitive and affective impairment, hormonal levels and/or autoantibody levels. It should lead to a broader understanding of the underlying pathogenesis and future treatment perspectives.

ETHICS AND DISSEMINATION

The study has been reviewed and approved by the Regional Ethical Review Board in Göteborg, Sweden. The results will be actively disseminated through peer-reviewed journals, national and international conference presentations and among patient organisations after an appropriate embargo time.

TRIAL REGISTRATION NUMBER

44321 at the public project database for research and development in Västra Götaland County, Sweden (https://www.researchweb.org/is/vgr/project/44321).

Increasing Energy Flux to Maintain Diet-Induced Weight Loss

Long-term maintenance of weight loss requires sustained energy balance at the reduced body weight. This could be attained by coupling low total daily energy intake (TDEI) with low total daily energy expenditure (TDEE; low energy flux), or by pairing high TDEI with high TDEE (high energy flux). Within an environment characterized by high energy dense food and a lack of need for movement, it may be particularly difficult for weight-reduced individuals to maintain energy balance in a low flux state. Most of these individuals will increase body mass due to an inability to sustain the necessary level of food restriction. This increase in TDEI may lead to the re-establishment of high energy flux at or near the original body weight. We propose that following weight loss, increasing physical activity can effectively re-establish a state of high energy flux without significant weight regain. Although the effect of extremely high levels of physical activity on TDEE may be constrained by compensatory reductions in non-activity energy expenditure, moderate increases following weight loss may elevate energy flux and encourage physiological adaptations favorable to weight loss maintenance, including better appetite regulation. It may be time to recognize that few individuals are able to re-establish energy balance at a lower body weight without permanent increases in physical activity. Accordingly, there is an urgent need for more research to better understand the role of energy flux in long-term weight maintenance.

Thyrotoxicosis Involves β2-Adrenoceptor Signaling to Negatively Affect Microarchitecture and Biomechanical Properties of the Femur

Background: Thyrotoxicosis increases bone turnover, resulting in net bone loss. Sympathetic nervous system (SNS) activation, via β2-adrenoceptor (β2-AR) signaling, also has osteopenic effects. Because thyroid hormones (TH) interact with the SNS to regulate several physiological processes, we hypothesized that this interaction also occurs to regulate bone mass. Previous studies support this hypothesis, as α2-AR knockout (KO) mice are less susceptible to thyrotoxicosis-induced osteopenia. Here, we evaluated whether TH-SNS interactions in bone involve β2-AR signaling. Methods: Thyrotoxicosis was induced in 120-day-old female and male mice with β2-AR gene inactivation (β2-AR^-/-) by daily treatment with supraphysiological doses of triiodothyronine (T3) for 12 weeks. The impact of thyrotoxicosis on femoral bone microarchitecture, remodeling, fracture risk, and gene expression of the receptor activator of nuclear factor-kappa-B (RANK)-RANK ligand (RANKL)-osteoprotegerin (OPG) pathway was evaluated. In addition, the effect of the β2-AR-specific agonist clenbuterol (CL) on cAMP accumulation was determined in osteoblastic (MC3T3-E1) cells treated with T3 and/or 17β-estradiol (E2). Results: Thyrotoxicosis negatively affected trabecular bone microarchitecture in wild-type (WT) females, but this effect was milder or nonexistent in β2-AR^-/- animals, whereas the opposite was seen in males. T3 treatment increased the femoral RANKL/OPG mRNA ratio and the endosteal perimeter and medullary area of the diaphysis in WT females and males, but not in β2-AR^-/- mice, suggesting that T3 promotes endosteal resorption in cortical bone, in a mechanism that involves β2-AR signaling. T3 treatment increased endocortical mineral apposition rate only in WT females but not in β2-AR^-/- mice, suggesting that TH also induce bone formation in a β2-AR signaling-dependent mechanism. T3 treatment decreased femoral resistance to fracture only in WT females, but not in KO mice. E2 and CL similarly increased cAMP accumulation in MC3T3-E1 cells; whereas T3 alone had no effect, but it completely blocked E2-stimulated cAMP accumulation, suggesting that some T3 effects on bone may involve E2/cAMP signaling in osteoblasts. Conclusions: These findings sustain the hypothesis that T3 interacts with the SNS to regulate bone morphophysiology in a β2-AR signaling-dependent mechanism. The data also reveal sex as an important modifier of skeletal manifestations of thyrotoxicosis, as well as a modifier of the TH-SNS interactions to control bone microarchitecture, remodeling, and resistance to fracture.

Relationship of Migraine and Tension-Type Headache With Hypothyroidism: A Literature Review

BACKGROUND

Migraine, tension-type headache, and hypothyroidism constitute very common medical conditions. Headache is one of the most common symptoms of hypothyroidism, occurring in approximately one-third of the patients. To date, data about the relationship between migraine and tension-type headache and thyroid dysfunction, and in particular hypothyroidism have been contradictory, while the underlying pathophysiological basis explaining this association is still unclear.

OBJECTIVE

In this review, we investigated the association between primary headaches and hypothyroidism, with the aim of shedding light on its pathophysiological basis.

METHODS

We conducted a systematic search in the MEDLINE database using both subject headings and keywords for headache, migraine, tension-type headache, thyroid hormones, and hypothyroidism, and we also examined manually the reference lists of all articles that met the inclusion criteria. Included studies were related to headache and thyroid disease comorbidity, with emphasis on hypothyroidism (ideally demonstrated by hormonal measurements), and with the term headache including migraine, tension-type headache, and headache attributed to hypothyroidism (HAH) based on the International Classification of Headache Disorders IIIb. Quality of studies was assessed by the Newcastle-Ottawa scale.

RESULTS

Of a total of 640 identified articles, 9 studies were included. Overall, there was vast heterogeneity across the included studies concerning population, study design and outcomes. Two studies investigated the HAH, with emphasis on the clinical characteristics of headache (time of onset, localization, quality, intensity, and response to hormonal replacement treatment). Five studies investigated comorbidity between migraine and thyroid disorders, especially hypothyroidism, and in the majority of them a positive association was demonstrated. One study found that headache, and particularly migraine, may increase the risk of developing hypothyroidism. Finally, only 1 study on chronic tension-type headache found coexistence of migraine and hypoactivity of the hypothalamus-pituitary-thyroid axis. The strengths and limitations of these studies are analyzed and possible pathophysiological mechanisms are suggested.

CONCLUSIONS

The existing data are considered inadequate to answer with certainty the relationship between headaches and thyroid disorders. According to our analysis, it seems that suggestions for a possible bidirectional association between headaches and especially migraine and hypothyroidism could exist. It hence lays the foundation for further research into the aforementioned association and its pathogenesis via large prospective multicenter studies.

Thyroid and Cardiovascular Disease: Research Agenda for Enhancing Knowledge, Prevention, and Treatment

Thyroid hormones have long been known to have a range of effects on the cardiovascular system. However, significant knowledge gaps exist concerning the precise molecular and biochemical mechanisms governing these effects and the optimal strategies for management of abnormalities in thyroid function in patients with and without preexisting cardiovascular disease. In September 2017, the National Heart, Lung, and Blood Institute convened a Working Group with the goal of developing priorities for future scientific research relating thyroid dysfunction to the progression of cardiovascular disease. The Working Group reviewed and discussed the roles of normal thyroid physiology, the consequences of thyroid dysfunction, and the effects of therapy in 3 cardiovascular areas: cardiac electrophysiology and arrhythmias, the vasculature and atherosclerosis, and the myocardium and heart failure. This report describes the current state of the field, outlines barriers and challenges to progress, and proposes research opportunities to advance the field, including strategies for leveraging novel approaches using omics and big data. The Working Group recommended research in 3 broad areas: (1) investigation into the fundamental biology relating thyroid dysfunction to the development of cardiovascular disease and into the identification of novel biomarkers of thyroid hormone action in cardiovascular tissues; (2) studies that define subgroups of patients with thyroid dysfunction amenable to specific preventive strategies and interventional therapies related to cardiovascular disease; and (3) clinical trials focused on improvement in cardiovascular performance and cardiovascular outcomes through treatment with thyroid hormone or thyromimetic drugs.

Thyroid and Cardiovascular Disease: Research Agenda for Enhancing Knowledge, Prevention, and Treatment

Thyroid hormones have long been known to have a range of effects on the cardiovascular system. However, significant knowledge gaps exist concerning the precise molecular and biochemical mechanisms governing these effects and the optimal strategies for management of abnormalities in thyroid function in patients with and without preexisting cardiovascular disease. In September 2017, The National Heart, Lung, and Blood Institute convened a Working Group with the goal of developing priorities for future scientific research relating thyroid dysfunction to the progression of cardiovascular disease. The Working Group reviewed and discussed the roles of normal thyroid physiology, the consequences of thyroid dysfunction, and the effects of therapy in three cardiovascular areas: cardiac electrophysiology and arrhythmias, the vasculature and atherosclerosis, and the myocardium and heart failure. This report describes the current state of the field, outlines barriers and challenges to progress, and proposes research opportunities to advance the field, including strategies for leveraging novel approaches using omics and big data. The Working Group recommended research in three broad areas: 1) investigation into the fundamental biology relating thyroid dysfunction to the development of cardiovascular disease and into the identification of novel biomarkers of thyroid hormone action in cardiovascular tissues; 2) studies that define subgroups of patients with thyroid dysfunction amenable to specific preventive strategies and interventional therapies related to cardiovascular disease; and 3) clinical trials focused on improvement in cardiovascular performance and cardiovascular outcomes through treatment with thyroid hormone or thyromimetic drugs.

3,5-Diiodo-L-Thyronine Exerts Metabolically Favorable Effects on Visceral Adipose Tissue of Rats Receiving a High-Fat Diet

When administered to rats receiving a high-fat diet (HFD), 3,5-diiodo-L-thyronine (3,5-T2) [at a dose of 25 μg/100 g body weight (BW)] is known to increase energy expenditure and to prevent HFD-induced adiposity. Here, we investigated which cellular and molecular processes in visceral white adipose tissue (VAT) contributed to the beneficial effect of 3,5-T2 over time (between 1 day and 4 weeks following administration). 3,5-T2 programmed the adipocyte for lipolysis by rapidly inducing hormone sensitive lipase (HSL) phosphorylation at the protein kinase A-responsive site Ser⁵⁶³, accompanied with glycerol release at the 1-week time-point, contributing to the partial normalization of adipocyte volume with respect to control (N) animals. After two weeks, when the adipocyte volumes of HFD-3,5-T2 rats were completely normalized to those of the controls (N), 3,5-T2 consistently induced HSL phosphorylation at Ser⁵⁶³, indicative of a combined effect of 3,5-T2-induced adipose lipolysis and increasing non-adipose oxidative metabolism. VAT proteome analysis after 4 weeks of treatment revealed that 3,5-T2 significantly altered the proteomic profile of HFD rats and produced a marked pro-angiogenic action. This was associated with a reduced representation of proteins involved in lipid storage or related to response to oxidative stress, and a normalization of the levels of those involved in lipogenesis-associated mitochondrial function. In conclusion, the prevention of VAT mass-gain by 3,5-T2 occurred through different molecular pathways that, together with the previously reported stimulation of resting metabolism and liver fatty acid oxidation, are associated with an anti adipogenic/lipogenic potential and positively impact on tissue health.