A normal thyroid status is crucial for body temperature homeostasis, as thyroid hormone regulates both heat loss and conservation as well as heat production in the thermogenic tissues. Brown adipose tissue (BAT) is the major site of non-shivering thermogenesis and an important target of thyroid hormone action. Thyroid hormone not only regulates the tissue’s sensitivity to sympathetic stimulation by norepinephrine but also the expression of uncoupling protein 1, the key driver of BAT thermogenesis. Vice versa, sympathetic stimulation of BAT triggers the expression of deiodinase type II, an enzyme that enhances local thyroid hormone availability and signaling. This review summarizes the current knowledge on how thyroid hormone controls BAT thermogenesis, aiming to dissect the direct actions of the hormone in BAT and its indirect actions via the CNS, browning of white adipose tissue or heat loss over body surfaces. Of particular relevance is the apparent dose dependency of the observed effects, as we find that minor or moderate changes in thyroid hormone levels often have different effects as compared to high pharmacological doses. Moreover, we conclude that the more recent findings require a reevaluation of older studies, as key aspects such as heat loss or central BAT activation may not have received the necessary attention during the interpretation of these early findings. Finally, we provide a list of what we believe are the most relevant questions in the field that to date are still enigmatic and require further studies.
Sarah Christine Sentis, Rebecca Oelkrug, and Jens Mittag
Sirazum Choudhury, Tricia Tan, Katharine Lazarus, and Karim Meeran
The introduction of adrenocortical extract in 1930 improved the life expectancy of hyhpoadrenal patients, with further increases seen after the introduction of cortisone acetate from 1948. Most patients are now treated with synthetic hydrocortisone, and incremental advances have been made with optimisation of daily dosing and the introduction of multidose regimens. There remains a significant mortality gap between individuals with treated hypoadrenalism and the general population. It is unclear whether this gap is a result of glucocorticoid over-replacement, under-replacement or loss of the circadian and ultradian rhythm of cortisol secretion, with the risk of detrimental excess glucocorticoid exposure at later times in the day. The way forwards will involve replacement of the diurnal cortisol rhythm with better glucocorticoid replacement regimens. The steroid profile produced by both prednisolone and dual-release hydrocortisone (Plenadren), provide a smoother glucocorticoid profile of cortisol than standard oral multidose regimens of hydrocortisone and cortisone acetate. The individualisation of prednisolone doses and lower bioavailability of Plenadren offer reductions in total steroid exposure. Although there is emerging evidence of both treatments offering better cardiometabolic outcomes than standard glucocorticoid replacement regimens, there is a paucity of evidence involving very low dose prednisolone (2–4 mg daily) compared to the larger doses (~7.5 mg) historically used. Data from upcoming clinical studies on prednisolone will therefore be of key importance in informing future practice.
Satoshi Higuchi, Hideki Ota, Yuta Tezuka, Kazumasa Seiji, Hidenobu Takagi, Jongmin Lee, Yi-Wei Lee, Kei Omata, Yoshikiyo Ono, Ryo Morimoto, Masataka Kudo, Fumitoshi Satoh, and Kei Takase
This study compared cardiac function, morphology, and tissue characteristics between two common subtypes of primary aldosteronism (PA) using a 3T MR scanner.
A retrospective, single-center, observational study.
We retrospectively reviewed 143 consecutive patients with PA, who underwent both adrenal venous sampling and cardiac magnetic resonance. We acquired cine, late gadolinium enhancement, and pre- and postcontrast myocardial T1-mapping images.
PA was diagnosed as unilateral aldosterone-producing adenoma (APA) in 70 patients and bilateral hyperaldosteronism (BHA) in 73. The APA group showed significantly higher plasma aldosterone concentration (PAC) and aldosterone to renin rate (ARR) than the BHA group. After controlling for age, sex, antihypertensive drugs, systolic and diastolic blood pressure, and disease duration, the parameters independently associated with APA were: left ventricular end-diastolic volume index (EDVI: adjusted odds ratio (aOR) = 1.06 (95% CI: 1.030–1.096), P < 0.01), end-systolic volume index (ESVI: 1.06 (1.017–1.113), P < 0.01), stroke index (SI: 1.07 (1.020–1.121), P < 0.01), cardiac index (CI: 1.001 (1.000–1.001), P < 0.01), and native T1 (1.01 (1.000–1.019), P = 0.038). Weak positive correlations were found between PAC and EDVI (R = 0.28, P < 0.01), ESVI (0.26, P < 0.01), and SI (0.18, P = 0.03); and between ARR and EDVI (0.25, P < 0.01), ESVI (0.24, P < 0.01), and native T1 (0.17, P = 0.047).
APA is associated with greater LV volumetric parameters and higher native T1 values, suggesting a higher risk of volume overload and myocardial damage.
Shih-Rong Lin, Shih-Fen Chen, Yu-Cih Yang, Chung-Y Hsu, and Yu-Chih Shen
Hyperthyroidism contributes to many other disease conditions, including neurodegenerative diseases. Parkinson’s disease (PD) is one of the most common neurodegenerative diseases. The purpose of this study was to investigate the risk of PD in patients with hyperthyroidism. A total of 8788 patients with hyperthyroidism and 8788 controls (without hyperthyroidism) matched by age, gender, index year, and Charlson Comorbidity Index (CCI) score were enrolled between 2000 and 2012. Patients were then followed until the end of 2013 using Taiwan’s National Health Insurance Research Database, at which time participants who developed PD were identified. Cox regression analysis was used to calculate the hazard ratio (HR) with a 95% CI of PD incidence rate between patients with hyperthyroidism and unaffected controls. Patients with hyperthyroidism had a significantly increased risk of PD compared with unaffected controls (1.21 vs 0.45 per 1000 person-years, HR: 2.69, 95% CI: 1.08–6.66) after adjusting for age, gender, CCI score, comorbidities, and antithyroid therapy. Hyperthyroidism and PD may share common manifestations. After excluding the first year of observation, a similar result is obtained (HR: 2.57, 95% CI: 1.61–4.01). Also, this study found that older age (HR: 3.74–8.53), more comorbidities (HR: 1.58–1.63), and specific comorbidities (brain injury (HR: 1.57) and cerebrovascular disease (HR: 3.44)) were associated with an increased risk of developing PD. Patients with hyperthyroidism have an increased risk of developing PD. Additional prospective clinical studies are warranted to examine the relationship between hyperthyroidism and PD and determine if there is an intervention that could reduce PD risk.
Xingrong Tan, Wenjing Hu, Shan Yang, Han Dai, Shangcheng Xu, Gangyi Yang, Ling Li, Shiguo Tang, and Yi Wang
The purpose of this study was to investigate the relationship between circulating zinc α 2-glycoprotein (ZAG), irisin, betatrophin and adiponectin concentrations and metabolic syndrome (MetS) components and to analyze the effects of blood glucose and insulin on these cytokine concentrations in vivo.
A total of 196 young women, including 78 healthy women and 118 women with MetS components, were recruited for this cross-sectional study. An oral glucose tolerance test and euglycemic-hyperinsulinemic clamp (EHC) were performed in healthy subjects and women with MetS components. An ELISA kit was used to measure serum ZAG, irisin, betatrophin, and adiponectin levels, and their relationship with the MetS components was analyzed.
In women with MetS components, circulating irisin and betatrophin levels were significantly higher than those in the healthy women ((207 (150–248) vs 178 (147–228); P < 0.05) for irisin; (0.51 (0.38–0.63) vs 0.38 (0.23–0.52); P < 0.001) for betatrophin), but circulating ZAG and adiponectin levels were significantly lower (39.8 (26.4–50.4) vs (46.7 (40.6–63.0); P < 0.001) for ZAG; (36.5 (22.0–47.6) vs 41.2 (35.7–54.7); P < 0.01) for adiponectin). FBG, WC, and triglyceride were significantly correlated with the circulating levels of these four cytokines (P < 0.001 or <0.05). All four cytokines were associated with MetS and its components. In response to increasing insulin levels, circulating ZAG concentrations were markedly increased in both healthy subjects and women with MetS components during the EHC. However, serum irisin, betatrophin, and adiponectin levels in both healthy subjects and women with MetS components were significantly reduced compared with baseline.
Serum ZAG, irisin, betatrophin and adiponectin were associated with MetS and might be biomarkers for screening MetS components.
Thera P Links, Trynke van der Boom, Wouter T Zandee, and Joop D Lefrandt
Thyroid hormone stimulates cardiac inotropy and chronotropy via direct genomic and non-genomic mechanisms. Hyperthyroidism magnifies these effects, resulting in an increase in heart rate, ejection fraction and blood volume. Hyperthyroidism also affects thrombogenesis and this may be linked to a probable tendency toward thrombosis in patients with hyperthyroidism. Patients with hyperthyroidism are therefore at higher risk for atrial fibrillation, heart failure and cardiovascular mortality. Similarly, TSH suppressive therapy for differentiated thyroid cancer is associated with increased cardiovascular risk. In this review, we present the latest insights on the cardiac effects of thyroid suppression therapy for the treatment of thyroid cancer. Finally, we will show new clinical data on how to implement this knowledge into the clinical practice of preventive medicine.
Monika Schaffner, Ursula Rochau, Nikolai Mühlberger, Annette Conrads-Frank, Vjollca Qerimi Rushaj, Gaby Sroczynski, Eftychia Koukkou, Betina Heinsbaek Thuesen, Henry Völzke, Wilhelm Oberaigner, and Uwe Siebert
More than 30% of the German population suffers from mild to moderate iodine deficiency causing goiter and other iodine deficiency disorders (IDDs). The economic burden of iodine deficiency is still unclear. We aimed to assess costs for prevention, monitoring and treatment of IDDs in Germany.
We performed a comprehensive cost analysis.
We assessed direct medical costs and direct non-medical costs for inpatient and outpatient care of IDDs and costs for productivity loss due to the absence of work in 2018. Additionally, we calculated total costs for an IDD prevention program comprising universal salt iodization (USI). We performed threshold analyses projecting how many cases of IDDs or related treatments would need to be avoided for USI to be cost-saving.
Annual average costs per case in the year of diagnosis were € 211 for goiter/thyroid nodules; € 308 for hyperthyroidism; and € 274 for hypothyroidism. Average one-time costs for thyroidectomy were € 4184 and € 3118 for radioiodine therapy. Average costs for one case of spontaneous abortion were € 916. Annual costs of intellectual disability were € 14,202. In the German population, total annual costs for USI would amount to 8 million Euro. To be cost-saving, USI would need to prevent, for example, 37,900 cases of goiter/thyroid nodules.
USI potentially saves costs, if a minimum amount of IDDs per year could be avoided. In order to recommend the implementation of USI, a full health-economic evaluation including a comprehensive benefit-harm assessment is needed.
Violeta Iotova, Camilla Schalin-Jäntti, Petra Bruegmann, Manuela Broesamle, Natasa Bratina, Vallo Tillmann, Olaf Hiort, and Alberto M Pereira
The European Reference Network on Rare Endocrine Conditions (Endo-ERN), operational since 2017, consists of 71 health care providers (HCPs) in 19 EU member states. Our objective was to assess education and knowledge on rare endocrine conditions.
Design and methods
A survey was developed and sent through the DIGIT-EUROSURVEY system to all Endo-ERN HCPs.
Response rate was 55% (n = 146), 95% physicians, 58% >20 years of experience, 96% academics. Largest knowledge gaps were reported for the transition and neonatal ages, and for the GPs. Less than 50% of HCPs had structured educational rare diseases (RD) plans, while 86% used RD specific guidelines. HCPs would share educational materials within Endo-ERN (74%), and participate in an accreditation model (85%). E-learning portals of the endocrine scientific societies used 58% (ESPE) and 64% (ESE). Most participants (90%) regarded Endo-ERN coordinated educational activities (annual meetings slots, webinars, etc.) as highly important and supported a common educational platform. Social media was perceived as important for educating patients (86%) but not for physicians (36%). Seventy-five % had developed patient education materials; only 31% had specific children’s materials, and by-country availability varied from 0 to 100%. Respondents provided newly diagnosed patients with their own material in the national language (81%); referred to advocacy groups (68%), and relevant online sources (50%). Respondents believed the European Commission should fund education through Endo-ERN.
Identified knowledge gaps in rare endocrine disorders set the basis for fast catch-up through collaboration, alignment with patients’ needs, and further development of existing and newly developed educational resources.
Alexander V Amram, Stephen Cutie, and Guo N Huang
Research conducted across phylogeny on cardiac regenerative responses following heart injury implicates endocrine signaling as a pivotal regulator of both cardiomyocyte proliferation and heart regeneration. Three prominently studied endocrine factors are thyroid hormone, vitamin D, and glucocorticoids, which canonically regulate gene expression through their respective nuclear receptors thyroid hormone receptor, vitamin D receptor, and glucocorticoid receptor. The main animal model systems of interest include humans, mice, and zebrafish, which vary in cardiac regenerative responses possibly due to the differential onsets and intensities of endocrine signaling levels throughout their embryonic to postnatal organismal development. Zebrafish and lower vertebrates tend to retain robust cardiac regenerative capacity into adulthood while mice and other higher vertebrates experience greatly diminished cardiac regenerative potential in their initial postnatal period that is sustained throughout adulthood. Here, we review recent progress in understanding how these three endocrine signaling pathways regulate cardiomyocyte proliferation and heart regeneration with a particular focus on the controversial findings that may arise from different assays, cellular-context, age, and species. Further investigating the role of each endocrine nuclear receptor in cardiac regeneration from an evolutionary perspective enables comparative studies between species in hopes of extrapolating the findings to novel therapies for human cardiovascular disease.
Xiuzhen Hou, Junfeng Zhang, Hehong Ma, Ming Li, and Pei Wang
Oxidative stress leads to insulin resistance and gestational diabetes mellitus (GDM). The nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling is an important anti-oxidative stress pathway, which can be activated by hypoxia-reoxygenation (H/R) treatment. We aimed to demonstrate the effects of H/R treatment on GDM symptoms as well as reproductive outcomes.
Pregnant C57BL/KsJ db/+ mice were used as a genetic GDM model. Plasma insulin and other biochemical indexes of plasma, insulin sensitivity, glucose intolerance, blood glucose and liver biochemical indexes were evaluated. Protein abundance of HO-1 and Nrf2 were assessed with Western blot.
H/R treatment markedly ameliorated β-cell insufficiency and glucose intolerance, suppressed oxidative stress in vivo, stimulated the activities of anti-oxidant enzymes, and led to improved reproductive outcomes. The beneficial effects of H/R treatment were mechanistically mediated via the restoration of Nrf2/HO-1 anti-oxidant signaling pathway in the liver of GDM mice.
Our study, for the first time, suggests that H/R treatment is a potentially novel therapeutic approach against GDM symptoms, by activating the Nrf2/HO-1 signaling pathway and inhibiting oxidative stress.