Thyroid Dysfunction in Heart Failure and Cardiovascular Outcomes

Unmasking High-Output Heart Failure: Beyond Conventional Paradigms

Heart failure (HF) poses a significant medical challenge, affecting millions of adults in the United States. High-output heart failure (HOHF) is a distinct subtype characterized by elevated cardiac output exceeding 8 L/min or a cardiac index >4 L/min/m². Patients with HOHF often present similarly to those with heart failure with reduced ejection fraction and heart failure with preserved ejection fraction. However, the underlying pathophysiology differs; triggered by a progressive decline in systemic vascular resistance, the ensuing elevation of cardiac output eventually leads to left ventricular remodeling and HF. Failure to differentiate HOHF from other variant forms of HF has implications for management, particularly relating to the use of vasodilator medications with potentially deleterious consequences, ensuing from the unrestrained adoption of societal guideline-directed medical therapy recommendations. Despite its clinical importance, HOHF remains under-examined in literature, with limited recognition and understanding among clinicians. This review aims to provide a comprehensive analysis of knowledge surrounding HOHF, exploring its definition, etiopathology, and underlying pathophysiological mechanisms. Recognizing the challenges in diagnosing HOHF, we propose a novel diagnostic algorithm tailored to address the subtleties of this often-misdiagnosed variant of HF.

Evaluation of thyroid function tests among children with neurological disorders

Background

Thyroid hormones (THs) are essential for brain development. Numerous studies have identified significant links between thyroid dysfunction and cognitive function. However, research on the significance and necessity of thyroid function tests in diagnosis of neurological disorders is limited and subject to controversy.

Methods

Our study employed a combination of meta-analysis and case-control design. For the meta-analysis, we conducted a systematic search of online databases for studies that compared thyroid function tests in children with neurological disorders to controls. In our case-control study, we recruited a total of 11836 children, comprising 7035 cases and 4801 healthy controls. Wilcoxon Rank Sum Test was used to determine characteristics of thyroid function between the cases and healthy controls. In order to exclude the false discovery rate (FDR), the Benjamini-Hochberg (BH) procedure is applied.

Results

A total of 12 relevant literature sources were included in the meta-analysis. Compared with controls, free thyroxine (FT4) levels were significantly decreased in neurological disorders in meta-analysis (MD = -0.29, 95% CI: -0.50 to -0.09), whereas thyroid-stimulating hormone (TSH) levels showed no significant difference (MD = -0.07, 95% CI: -0.36 to 0.21). In our case-control study, levels of free thyroxine (FT4), total triiodothyronine (TT3), total thyroxine (TT4), and anti-thyroglobulin antibodies (TG-Ab) were notably reduced among individuals with neurological disorders, compared with healthy controls (P<0.001, P<0.001, P=0.036, P=0.006). However, thyroid-stimulating hormone (TSH) levels did not show any statistically significant differences among the cases and controls.

Conclusions

Our research demonstrates that, in comparison to controls, children with neurological disorders exhibited a significant decrease in FT4 levels, while TSH levels remained unchanged. This finding provides a reference for potential serum marker of neurological disorders in children. Replication in future studies with the assessment of THs is needed to determine whether thyroid function should be included as a routine screening in these children.

The Impact of Thyroid Hormone Imbalance on Cardiovascular Health: A Population-Based Study

INTRODUCTION

Thyroid hormone imbalances are known to significantly affect cardiovascular health, contributing to conditions such as arrhythmias, dyslipidemia, and hypertension. Given the increasing prevalence of thyroid dysfunction and its potential impact on cardiovascular outcomes, early diagnosis and intervention are crucial, particularly within specific regional populations.

OBJECTIVE

This study aimed to evaluate the impact of thyroid hormone imbalance on cardiovascular health outcomes in patients at Lady Reading Hospital, Peshawar, over a 24-month period.

MATERIALS AND METHODS

A prospective cohort study was conducted between October 2022 and September 2024, involving 150 adult patients diagnosed with thyroid dysfunction, categorized into subclinical, hyperthyroid, and hypothyroid groups. The study assessed key cardiovascular health indicators, including blood pressure, lipid profiles, heart rate, and electrocardiograms (ECGs), at baseline and during follow-up visits at 6, 12, and 24 months. Participants were included if they met the biochemical criteria for thyroid dysfunction and had no significant pre-existing cardiovascular disease. Data were collected through medical records and standardized questionnaires. The Institutional Review Board at Lady Reading Hospital approved the study.

RESULTS

Dyslipidemia was found in 90 participants (60%), hypertension in 99 participants (66%), and hypothyroidism in 76 participants (72%). Arrhythmias were observed in 14 individuals (46%) with hyperthyroidism. ECG findings revealed sinus bradycardia in 32 participants (30%) with hypothyroidism and sinus tachycardia in 23 participants (76%) with hyperthyroidism. Multivariate analysis showed that hypothyroidism significantly increased the odds of hypertension (OR = 3.2, p = 0.001), dyslipidemia (OR = 2.9, p = 0.003), and arrhythmias (OR = 4.3, p < 0.001).

CONCLUSION

Thyroid hormone imbalance has a profound impact on cardiovascular health, with hyperthyroidism linked to arrhythmias and hypothyroidism associated with hypertension and dyslipidemia. Subclinical thyroid dysfunction also increases cardiovascular risks, emphasizing the need for early detection and region-specific management strategies. This study provides valuable insights into the long-term cardiovascular effects of thyroid dysfunction in the Khyber Pakhtunkhwa (KPK) region, supporting the importance of routine screening and timely intervention.

Euthyroid sick syndrome predicts the risk of ischemic stroke-associated pneumonia in the acute stage of ischemic stroke: a nested case-control study

Objective

Ischemic stroke-associated pneumonia (iSAP) affects about 10% of acute ischemic stroke patients during hospitalization. Current prediction scales for iSAP are insufficient. Identifying early biomarkers for stroke-associated pneumonia is crucial for improving patient outcomes. This study aimed to investigate the predictive value of euthyroid sick syndrome (ESS) for iSAP in acute-stage of ischemic stroke patients.

Methods

We studied 1767 acute ischemic stroke patients within one week of symptom onset, categorizing them into an infection group (iSAP, n=376) and control group (control, n=1391). COX regression analysis was used to identify the potential risk and protected factors. Kaplan-Meier time-event curves and Log-Rank tests were performed to differentiate infection time in patients with ESS or normal T3 group.

Results

The iSAP group had higher rates of risk factors like older age, atrial fibrillation, COPD, and ESS, along with elevated levels of WBC, CRP,and FT4 levels (all P < 0.001). Conversely, iSAP patients had lower GCS scores, eGFR, TSH, T3, FT3 (all P < 0.001) and T4 levels (P = 0.005) upon admission. No significant differences were observed in sex, smoking history, hypertension, diabetes, or LDL-C levels (P > 0.05). COX regression analysis identified age, KWST scores, leukocyte count, CRP, and ESS (all P < 0.001) as significantly correlated with iSAP. ROC analysis revealed ESS as a predictor with sensitivity of 35.64% and specificity of 87.92% for SAP prediction, like atrial fibrillation and higher than COPD and eGFR.

Conclusion

ESS at admission predicts a higher risk of stroke-associated pneumonia in acute-stage of ischemic stroke.

Nanoscale organization of cardiac calcium channels is dependent on thyroid hormone status

Thyroid hormone dysfunction is frequently observed in patients with chronic illnesses including heart failure, which increases the risk of adverse events. This study examined the effects of thyroid hormones (THs) on cardiac transverse-tubule (TT) integrity, Ca2+ sparks, and nanoscale organization of ion channels in excitation-contraction (EC) coupling, including L-type calcium channel (CaV1.2), ryanodine receptor type 2 (RyR2), and junctophilin-2 (Jph2). TH deficiency was established in adult female rats by propyl-thiouracil (PTU) ingestion for 8 wk; followed by randomization to continued PTU without or with oral triiodo-l-thyronine (T3; 10 µg/kg/day) for an additional 2 wk (PTU + T3). Confocal microscopy of isolated cardiomyocytes (CMs) showed significant misalignment of TTs and increased Ca2+ sparks in thyroid-deficient CMs. Density-based spatial clustering of applications with noise (DBSCAN) analysis of stochastic optical reconstruction microscopy (STORM) images showed decreased (P < 0.0001) RyR2 cluster number per cell area in PTU CMs compared with euthyroid (EU) control myocytes, and this was normalized by T3 treatment. CaV1.2 channels and Jph2 localized within a 210 nm radius of the RyR2 clusters were significantly reduced in PTU myocytes, and these values were increased with T3 treatment. A significant percentage of the RyR2 clusters in the PTU myocytes had neither CaV1.2 nor Jph2, suggesting fewer functional clusters in EC coupling. Nearest neighbor distances between RyR2 clusters were greater (P < 0.001) in PTU cells compared with EU- and T3-treated CMs that correspond to disarray of TTs at the sarcomere z-discs. These results support a regulatory role of T3 in the nanoscale organization of RyR2 clusters and colocalization of CaV1.2 and Jph2 in optimizing EC coupling.NEW & NOTEWORTHY Thyroid hormone (TH) dysfunction exacerbates preexisting heart conditions leading to an increased risk of premature morbidity/mortality. Triiodo-l-thyronine (T3) optimizes cardiac excitation-contraction (EC) coupling by maintaining myocardial T-tubule (TT) structures and organization of calcium ion channels. Single-molecule localization microscopy shows T3 effects on the clustering of ryanodine receptors (RyR2) with colocalization of L-type calcium channels (CaV1.2) and junctophilin-2 (Jph2) at TT-SR structures. Heart disease with subclinical hypothyroidism/low T3 syndrome may benefit from TH treatment.

Thyroid dysfunction in nonvalvular atrial fibrillation and clinical outcomes

BACKGROUND

Thyroid dysfunction's effects on those who have been diagnosed with atrial fibrillation have not been well investigated. We looked at how thyroid function among patients with pre-existing atrial fibrillation related to thromboembolic risk and clinical outcomes.

METHODS

We gathered the medical information of patients diagnosed with nonvalvular atrial fibrillation (NVAF) between 2016 and 2020 at Dongguan People's Hospital. We then assessed the correlation between thyroid dysfunction and thrombotic risk (CHA2DS2-VASc) as well as the occurrence of clinical composite endpoint (all-cause death, heart failure, systemic embolism and hemorrhage events).

RESULTS

Of 1329 patients were admitted, 82.6% were euthyroid, 7.4% had subclinical hyperthyroidism, 4.2% had subclinical hypothyroidism, and 6.7% had low triiodothyronine (T3) syndrome. Lower levels of total triiodothyronine (TT3) were linked to an increased risk of thromboembolism (P < 0.005). During a median follow-up period of 1.84 years, there were 608 clinical composite endpoint occurrences. In the adjusted model, Low T3 syndrome was linked to a higher risk of the clinical composite endpoint (HR, 1.68; 95% CI, 1.20-2.37; P < 0.05) in comparison to euthyroidism. Specifically, low T3 syndrome was linked to a higher risk of heart failure (HR, 1.52; 95%CI, 1.01-2.30; P < 0.05) and all-cause death (HR, 3.34; 95% CI, 1.76-6.36; P < 0.001).

CONCLUSION

Low T3 syndrome are linked to an increased risk of heart failure and all-cause death in individuals with NVAF. And Patients with NVAF and low TT3 levels have a higher risk of thromboembolism.

Construction of a metabolism-malnutrition-inflammation prognostic risk score in patients with heart failure with preserved ejection fraction: a machine learning based Lasso-Cox model

BACKGROUND

Metabolic disorder, malnutrition and inflammation are involved and interplayed in the mechanisms of heart failure with preserved ejection fraction (HFpEF). We aimed to construct a Metabolism-malnutrition-inflammation score (MIS) to predict the risk of death in patients with HFpEF.

METHODS

We included patients diagnosed with HFpEF and without infective or systemic disease. 20 biomarkers were filtered by the Least absolute shrinkage and selection operator (Lasso)-Cox regression. 1000 times bootstrapping datasets were generated to select biomarkers that appeared above 95% frequency in repetitions to construct the MIS.

RESULTS

Among 1083 patients diagnosed with HFpEF, 342 patients (31.6%) died during a median follow-up period of 2.5 years. The MIS was finally constructed based on 6 biomarkers, they were albumin (ALB), red blood cell distribution width-standard deviation (RDW-SD), high-sensitivity C-reactive protein (hs-CRP), lymphocytes, triiodothyronine (T3) and uric acid (UA). Incorporating MIS into the basic predictive model significantly increased both discrimination (∆C-index = 0.034, 95% CI 0.013-0.050) and reclassification (IDI, 6.6%, 95% CI 4.0%-9.5%; NRI, 22.2% 95% CI 14.4%-30.2%) in predicting all-cause mortality. In the time-dependent receiver operating characteristic (ROC) analysis, the mean area under the curve (AUC) for the MIS was 0.778, 0.782 and 0.772 at 1, 3, and 5 years after discharge in the cross-validation sets. The MIS was independently associated with all-cause mortality (hazard ratio: 1.98, 95% CI [1.70-2.31], P < 0.001).

CONCLUSIONS

A risk score derived from 6 commonly used inflammatory, nutritional, thyroid and uric acid metabolic biomarkers can effectively identify high-risk patients with HFpEF, providing potential individualized management strategies for patients with HFpEF.

Association of Thyroid Dysfunction in Individuals ≥ 65 Years of Age With Subclinical Cardiac Abnormalities

CONTEXT

The relationship between thyroid dysfunction and measures of myocardial disease in older individuals remains to be defined.

OBJECTIVE

To evaluate the impact of thyroid dysfunction on structure and function of the left heart chambers and blood markers of cardiac disease.

METHODS

Cross-sectional analysis of the Cardiovascular Health Study, a community-based cohort of older individuals recruited from 4 urban areas in the United States. Of 3163 participants studied, 2477 were euthyroid, 465 had subclinical hypothyroidism (SCH), 47 overt hypothyroidism (OH), 45 endogenous (endo) subclinical hyperthyroidism (endo-SCT), and 129 had exogenous (exo) SCT due to thyroid hormone supplementation. Participants underwent clinical evaluation, blood sampling and biomarker measurement, 2-dimensional and speckle tracking echocardiography for assessment of left heart myocardial deformation, circulating biomarkers of diastolic overload (NT-proBNP), fibrosis (sST2, gal-3), and cardiomyocyte injury (hs-cTnT).

RESULTS

SCH was associated with higher NT-proBNP (beta = 0.17, P = .004), whereas OH was associated with higher hs-cTnT (beta = 0.29, P = .005). There were also suggestive associations of SCH with higher sST2, as well as endo-SCT with higher gal-3 and lower (worse) left atrial reservoir strain. Left ventricular longitudinal strain and end diastolic strain rate did not differ significantly from euthyroid participants in SCH, OH, or exo-SCT.

CONCLUSION

In this free-living elderly cohort, subclinical and overt hypothyroidism were associated with abnormalities of blood biomarkers consistent with diastolic overload and myocardial necrosis respectively, whereas subclinical hyperthyroidism tended to be associated with myocardial fibrosis and decreased left atrial strain. Our findings could represent stage B heart failure and illuminate distinct aspects of the pathobiology of heart disease related to thyroid gland dysfunction with potential clinical implications.

Subclinical hypothyroidism predicts outcome in heart failure: insights from the T.O.S.CA. registry

Subclinical hypothyroidism (SH), defined as increased serum thyroid-stimulating hormone (TSH) with normal free T4 (fT4) levels, is frequently observed in the general population. Prevalence ranges from 0.6% to 1.8% in the adult population, depending on age, sex, and iodine intake. Several studies reported a worse prognosis in patients with heart failure with reduced ejection fraction (HFrEF) and SH, but they considered heterogeneous populations suffering mainly from severe SH. Aim of this study was to evaluate if SH was independently associated with the occurrence of cardiovascular death considering 30 months of follow-up. 277 HFrEF patients enrolled in the prospective, multicenter, observational T.O.S.CA. (Terapia Ormonale Scompenso CArdiaco) registry, were included in this analysis. Patients were divided into two groups according to the presence of SH (serum TSH levels > 4.5 mIU/L with normal fT4 levels). Data regarding clinical status, echocardiography, and survival were analyzed. Twenty-three patients displayed SH (87% mild vs 13% severe), while 254 were euthyroid. No differences were found in terms of age, sex, HF etiology, and left ventricular ejection fraction. When compared with the euthyroid group, SH patients showed higher TSH levels (7.7 ± 4.1 vs 1.6 ± 0.9, p < 0.001), as expected, with comparable levels of fT4 (1.3 ± 0.3 vs 1.3 ± 0.3, p = NS). When corrected for established predictors of poor outcome in HF, the presence of SH resulted to be an independent predictor of cardiovascular mortality (HR: 2.96; 5-95% CI:1.13-7.74; p = 0.03). Since thyroid tests are widely available and inexpensive, they should be performed in HF patients to detect subclinical disorders, evaluate replacement therapy, and improve prognosis.

Prognostic implications of thyroid hormones in acute aortic dissection: mediating roles of renal function and coagulation

Background

Thyroid hormones significantly influence cardiovascular pathophysiology, yet their prognostic role in acute aortic dissection (AAD) remains inadequately explored. This study assesses the prognostic value of thyroid hormone levels in AAD, focusing on the mediating roles of renal function and coagulation.

Methods

We included 964 AAD patients in this retrospective cohort study. Utilizing logistic regression, restricted cubic splines, and causal mediation analysis, we investigated the association between thyroid hormones and in-hospital mortality and major adverse cardiovascular events (MACEs).

Results

In AAD patients overall, an increase of one standard deviation in FT4 levels was associated with a 31.9% increased risk of MACEs (OR 1.319; 95% CI 1.098-1.584) and a 36.1% increase in in-hospital mortality (OR 1.361; 95% CI 1.095-1.690). Conversely, a higher FT3/FT4 ratio was correlated with a 20.2% reduction in risk of MACEs (OR 0.798; 95% CI 0.637-0.999). This correlation was statistically significant predominantly in Type A AAD, while it did not hold statistical significance in Type B AAD. Key renal and coagulation biomarkers, including blood urea nitrogen, creatinine, cystatin C, prothrombin time ratio, prothrombin time, and prothrombin time international normalized ratio, were identified as significant mediators in the interplay between thyroid hormones and MACEs. The FT3/FT4 ratio exerted its prognostic influence primarily through the mediation of renal functions and coagulation, while FT4 levels predominantly impacted outcomes via a partial mediation effect on coagulation.

Conclusion

FT4 levels and the FT3/FT4 ratio are crucial prognostic biomarkers in AAD patients. Renal function and coagulation mediate the association between the thyroid hormones and MACEs.

Maternal hypothyroidism and subsequent metabolic outcomes in children: a systematic review and meta-analysis

INTRODUCTION

As the fetus relies on maternal thyroid hormones in early pregnancy, maternal hypothyroidism plays an important role in fetal development. However, the association between maternal hypothyroidism and metabolic disease in offspring is unclear.

OBJECTIVE

To examine the association between maternal hypothyroidism in pregnancy and metabolic outcomes (obesity, hypertension, type 2 diabetes mellitus, and dyslipidemia) in children < 18 years.

METHODS

We systematically searched 5 databases from inception to May 2023. Eligible studies included cohort, case-control, and randomized controlled trials involving children born to mothers with or without hypothyroidism in pregnancy. Data were pooled across studies using random-effects models for outcomes reported in at least three studies. Quality assessment was performed using the ROBINS-E tool for observational studies and the Cochrane Risk of Bias tool for trials.

RESULTS

The search identified 3221 articles, of which 7 studies were included (1 trial, 6 observational). All studies were conducted outside of North America and ranged in size from 250 to > 1 million children. The follow-up time ranged from 6 to 20 years. Included studies support an increased risk of hypertension and glucose dysregulation in offspring exposed to maternal hypothyroidism (hypertension: OR 1.08, 95% CI 0.75, 1.57 and HR 1.81, 95% CI 1.21, 2.69; diabetes: RR 2.7, 95% CI 0.7, 10). In the pooled analysis, maternal hypothyroidism was not associated with obesity in offspring (OR 1.04, 95% CI 0.64, 1.70).

CONCLUSION

This study found inconsistent evidence on the association between maternal hypothyroidism in pregnancy and metabolic outcomes in offspring, though associations with hypertension and glucose dysregulation are possible.

Clearing the Skepticism about Subclinical Hypothyroidism: Is It Beneficial to Treat Patients with Thyroid-Stimulating Hormone >4.5 and <10 mIU/L?

Subclinical hypothyroidism (SCH) is a heterogeneous clinical condition ranging from asymptomatic to wide variety of clinical manifestations, which are often nonspecific. Being a common laboratory finding, clinicians often face the dilemma of whether to treat or not. Threshold of 10 mIU/L of thyroid-stimulating hormone (TSH) is often used as a cutoff limit to offer treatment. However, still, debate remains on whether to treat less than 10 mIU/L considering special clinical conditions like pregnancy. Whether SCH exists, is screening needed in asymptomatic individuals, is treating asymptomatic cases beneficial or harmful and what threshold level of TSH to be considered for treatment are all potential questions that need to be answered.

Does subclinical hypothyroidism affect the prognosis of patients with chronic systolic heart failure: A systematic review and meta-analysis

BACKGROUND

Chronic systolic heart failure (CSHF) is a significant health burden with high morbidity and mortality. The role of subclinical hypothyroidism (SCH) in the prognosis of CSHF patients remains a critical area of inquiry. This systematic review and meta-analysis aim to elucidate the impact of SCH on the prognosis of patients with CSHF.

METHODS

Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, this meta-analysis employed a comprehensive search strategy across major databases including PubMed, Embase, Web of Science, and the Cochrane Library. The Patient, Intervention, Comparison, Outcome framework guided the inclusion of studies focusing on patients with CSHF, comparing those with and without SCH. Quality assessment was performed using the Newcastle-Ottawa scale. Statistical analyses assessed heterogeneity and publication bias, employing fixed-effect or random-effects models based on heterogeneity levels.

RESULTS

From an initial pool of 1439 articles, 8 studies met the stringent inclusion criteria. These studies, conducted across diverse geographical regions, highlighted the relationship between SCH and all-cause mortality, cardiac events, and subgroup differences in CSHF patients. The meta-analysis revealed SCH as a significant risk factor for all-cause mortality (HR = 1.42) and cardiac events (HR = 1.46). Subgroup analysis indicated variability in risk based on region, sample size, age, and follow-up duration. Sensitivity analysis confirmed the stability of these findings, and publication bias assessment indicated symmetric funnel plot and nonsignificant Egger test results.

CONCLUSIONS

SCH emerges as a predictive factor for all-cause mortality, cardiovascular events, and rehospitalization in CSHF patients. This finding underscores the importance of screening for SCH in CSHF patients, highlighting its potential role in improving patient prognosis.

Hypothyroidism and metabolic cardiovascular disease

Cardiovascular disease (CVD) remains the leading cause of death worldwide, representing a major health issue of social and economic relevance. Both hyperthyroidism and hypothyroidism are very common in the adult population, and both disorders may contribute to the onset and progression of CVD. After a brief description of the role of thyroid hormones (THs) on the physiology of the cardiovascular system and the potential mechanism that links THs alterations with changes in cardiac function, blood pressure, endothelial function, and lipid levels, we review updated data about the clinical impact of overt hypothyroidism (OH) and subclinical hypothyroidism (SCH) on CV risk, CVD, and mortality. Furthermore, we summarize the current evidence for treating SCH with levothyroxine (L-T4). Several guidelines of distinguished endocrine societies recommend treatment for SCH with TSH higher than 10 mIU/L, where the benefit of L-T4 therapy is more evident for younger people, but still controversial in those aged over 65 years. Based on current knowledge, more research efforts are needed to better address the clinical management of CV risk and CVD in the elderly affected by SCH.

Cardiovascular mechanisms of thyroid hormones and heart failure: Current knowledge and perspectives

A multiple hormonal imbalance that accompanies heart failure (HF) may have a significant impact on the clinical course in such patients. The non-thyroidal illness syndrome (NTIS), also referred to as euthyroid sick syndrome or low triiodothyronine syndrome, can be found in about 30% of patients with HF. NTIS represents a systemic adaptation to chronic illness that is associated with increased cardiac and overall mortality in patients with HF. While conclusions on thyroid-stimulating hormone, free triiodothyronine, total and free thyroxine are currently unresolved, serum total triiodothyronine levels and the ratio of free triiodothyronine to free thyroxine seem to provide the best correlates to the echocardiographic, laboratory and clinical parameters of disease severity. HF patients with either hyper- or hypothyroidism should be treated according to the appropriate guidelines, but the therapeutic approach to NTIS, with or without HF, is still a matter of debate. Possible treatment options include better individual titration of levothyroxine therapy, combined triiodothyronine plus thyroxine therapy and natural measures to increase triiodothyronine. Future research should further examine the cellular and tissue mechanisms of NTIS as well as new therapeutic avenues in patients with HF.

Prevalence and differences in the co-administration of drugs known to interact: an analysis of three distinct and large populations

BACKGROUND

The co-administration of drugs known to interact greatly impacts morbidity, mortality, and health economics. This study aims to examine the drug-drug interaction (DDI) phenomenon with a large-scale longitudinal analysis of age and gender differences found in drug administration data from three distinct healthcare systems.

METHODS

This study analyzes drug administrations from population-wide electronic health records in Blumenau (Brazil; 133 K individuals), Catalonia (Spain; 5.5 M individuals), and Indianapolis (USA; 264 K individuals). The stratified prevalences of DDI for multiple severity levels per patient gender and age at the time of administration are computed, and null models are used to estimate the expected impact of polypharmacy on DDI prevalence. Finally, to study actionable strategies to reduce DDI prevalence, alternative polypharmacy regimens using drugs with fewer known interactions are simulated.

RESULTS

A large prevalence of co-administration of drugs known to interact is found in all populations, affecting 12.51%, 12.12%, and 10.06% of individuals in Blumenau, Indianapolis, and Catalonia, respectively. Despite very different healthcare systems and drug availability, the increasing prevalence of DDI as patients age is very similar across all three populations and is not explained solely by higher co-administration rates in the elderly. In general, the prevalence of DDI is significantly higher in women - with the exception of men over 50 years old in Indianapolis. Finally, we show that using proton pump inhibitor alternatives to omeprazole (the drug involved in more co-administrations in Catalonia and Blumenau), the proportion of patients that are administered known DDI can be reduced by up to 21% in both Blumenau and Catalonia and 2% in Indianapolis.

CONCLUSIONS

DDI administration has a high incidence in society, regardless of geographic, population, and healthcare management differences. Although DDI prevalence increases with age, our analysis points to a complex phenomenon that is much more prevalent than expected, suggesting comorbidities as key drivers of the increase. Furthermore, the gender differences observed in most age groups across populations are concerning in regard to gender equity in healthcare. Finally, our study exemplifies how electronic health records' analysis can lead to actionable interventions that significantly reduce the administration of known DDI and its associated human and economic costs.

Takotsubo syndrome outcomes predicted by thyroid hormone signature: insights from cluster analysis of a multicentre registry

BACKGROUND

Recently, abnormal thyroid function was shown to be common in patients with Takotsubo syndrome (TTS), being classified into "endocrine-type" and "stress-type" responses. The aim of this study was to investigate the association between thyroid homeostasis and TTS in a larger international registry.

METHODS

In total 288 patients with TTS were enrolled through the GEIST multicentre registry from Germany, Italy and Spain. Thyrotropin (TSH), free T4 (FT4) and free T3 (FT3) concentrations were analysed at admission. Data were collected both retrospectively and prospectively from 2017 onwards. Primary endpoints included in-hospital and all-cause fatality, determined by cluster analysis using an unsupervised machine learning algorithm (k-medoids).

FINDINGS

Three clusters were identified, classifying TTS with low (TSLT), high (TSHT) and normal (TSNT) thyroid output, based on TSH and FT4 levels in relation to the median thyroid's secretory capacity (SPINA-GT). Although TSH and FT4 concentrations were similar among survivors and non-survivors, these clusters were significantly associated with patient outcomes. In the longitudinal Kaplan-Meier analysis including in- and out-of-hospital survival, the prognosis related to concentrations of TSH, FT4, and FT3 as well as SPINA-GT, deiodinase activity (SPINA-GD) and clusters. Patients in the TSHT cluster and with cardiogenic shock had a lower initial left ventricular ejection fraction (LVEF).

INTERPRETATION

This study suggests that thyroid hormones may impact the evolution and prognosis of TTS. The findings indicate that thyroid-derived biomarkers may help identify high-risk patients and pave the way for novel personalized and preventive therapeutic options.

FUNDING

This research was not funded by any public, commercial, or not-for-profit agencies.

The Relationship between Subclinical Hypothyroidism and Carotid Intima-Media Thickness as a Potential Marker of Cardiovascular Risk: A Systematic Review and a Meta-Analysis

BACKGROUND AND OBJECTIVES

Thyroid dysfunction is known to have significant consequences on the cardiovascular system. The correlation between carotid intima-media thickness (CIMT) and subclinical hypothyroidism (SCH) has been frequently evaluated in clinical studies in recent years. This study aimed to evaluate the significance of this association through a meta-analysis.

METHODS

We conducted a systematic search of PubMed, MedLine, Scopus, and Web of Science databases using the keywords 'subclinical hypothyroidism and carotid intima-media thickness', from the beginning of each database until January 2023. We established the inclusion and exclusion criteria and considered studies that met the inclusion criteria. We used Jamovi for statistical analysis of the data.

RESULTS

We identified 39 observational studies that met the inclusion criteria, with 3430 subjects: 1545 SCH and 1885 EU. Compared to euthyroid subjects (EU), subjects with subclinical hypothyroidism (SCH) had significantly increased carotid intima-media thickness (CIMT) values; the estimated average mean difference was 0.08 (95% CI 0.05 to 0.10), p < 0.01, I2 = 93.82%. After the sensitivity analysis, a total of 19 from the 39 abovementioned studies were analyzed, with most studies showing a positive association between SCH and thickening of the carotid wall; the estimated average mean difference was 0.04 (95% CI 0.02 to 0.07), p = 0.03, I2 = 77.7. In addition, female sex, advanced age, and high cholesterol levels statistically significantly influenced this association.

CONCLUSIONS

Our meta-analysis indicates a significant positive association between SCH and increased CIMT, but with some limitations.

Evaluation of multiple organophosphate insecticide exposure in relation to altered thyroid hormones in NHANES 2007-2008 adult population

The thyroid gland is susceptible to chemical exposure such as organophosphate insecticides (OPIs). With the ubiquitous nature of these products, humans are simultaneously exposed to a multitude of chemicals. This study aimed to evaluate the association between an individual and a mixture of OPI metabolites and changes in serum thyroid hormone (TH) concentrations. The analyzed data were 1,434 participants from the United States National Health and Nutrition Examination Surveys (NHANES) cycle 2007-2008. Generalized linear model (GLM) regression, weighted quantile sum (WQS), and adaptive least absolute shrinkage and selection operator (adaptive LASSO) regression were used to investigate the associations between urinary OPI metabolites and altered serum THs. In GLM, all of the five urinary OPI metabolites were inversely associated with free triiodothyronine (FT3) among the male subjects; meanwhile, higher thyroglobulin (Tg) was related to dimethylphosphate (DMP). Moreover, in WQS models, the metabolite mixture induced FT3 down-regulation (β = -0.209 (95% CI: -0.310, -0.114)), and caused an increased Tg concentration (β = 0.120 (95% CI: 0.024, 0.212)), however, any significant association was observed among female participants. Consistently, the weighted index and LASSO coefficient demonstrated dimethylthiophosphate (DMTP) as the strongest metabolite in the FT3 model (mean weight= 3.449e-01 and β =-0.022, respectively), and dimethylphosphate (DMP) represented the highest association in the Tg model (mean weight= 9.873e-01 and β =-0.020, respectively). Further research is required to confirm our results and investigate the clinical impacts of these disruptions.

Proteomic Associations of Adverse Outcomes in Human Heart Failure

BACKGROUND

Identifying novel molecular drivers of disease progression in heart failure (HF) is a high-priority goal that may provide new therapeutic targets to improve patient outcomes. The authors investigated the relationship between plasma proteins and adverse outcomes in HF and their putative causal role using Mendelian randomization.

METHODS AND RESULTS

The authors measured 4776 plasma proteins among 1964 participants with HF with a reduced left ventricular ejection fraction enrolled in PHFS (Penn Heart Failure Study). Assessed were the observational relationship between plasma proteins and (1) all-cause death or (2) death or HF-related hospital admission (DHFA). The authors replicated nominally significant associations in the Washington University HF registry (N=1080). Proteins significantly associated with outcomes were the subject of 2-sample Mendelian randomization and colocalization analyses. After correction for multiple testing, 243 and 126 proteins were found to be significantly associated with death and DHFA, respectively. These included small ubiquitin-like modifier 2 (standardized hazard ratio [sHR], 1.56; P<0.0001), growth differentiation factor-15 (sHR, 1.68; P<0.0001) for death, A disintegrin and metalloproteinase with thrombospondin motifs-like protein (sHR, 1.40; P<0.0001), and pulmonary-associated surfactant protein C (sHR, 1.24; P<0.0001) for DHFA. In pathway analyses, top canonical pathways associated with death and DHFA included fibrotic, inflammatory, and coagulation pathways. Genomic analyses provided evidence of nominally significant associations between levels of 6 genetically predicted proteins with DHFA and 11 genetically predicted proteins with death.

CONCLUSIONS

This study implicates multiple novel proteins in HF and provides preliminary evidence of associations between genetically predicted plasma levels of 17 candidate proteins and the risk for adverse outcomes in human HF.

Thyroid dysfunction and mortality in cardiovascular hospitalized patients

Background

Thyroid dysfunction (TD) is associated with increased cardiovascular morbidity and mortality. Early detection may influence the clinical management.

Objective

To determine the prevalence, predictors, and prognostic value of TD among hospitalized cardiac patients.

Methods

A retrospective analysis of a 12-year database consisting of nonselectively adult patients admitted to a Cardiology Department and who were all screened for serum thyroid-stimulation-hormone (TSH) levels . Statistical analysis of demographic and clinical characteristics, mortality and length of hospital stay (LOS) was performed.

Results

A total of 14369 patients were included in the study; mean age was 67 years, 38.3% females. 1465 patients (10.2%) had TD. The most frequent type of TD was mildly elevated TSH (5.4%) followed by mildly reduced TSH (2.1%), markedly elevated TSH (1.5%), and markedly reduced TSH (1.2%). Female gender, history of hypothyroidism, heart failure, atrial fibrillation, renal failure and amiodarone use were significantly associated with TD. During follow-up 2975 (20.7%) patients died. There was increased mortality in the mildly reduced TSH subgroup (hazard ratio [HR] =1.44), markedly elevated TSH subgroup (HR=1.40) and mildly elevated TSH subgroup (HR=1.27). LOS was longer for patients with TD; the longest stay was observed in the markedly elevated TSH subgroup (odds ratio=1.69).

Conclusion

The prevalence of TD in hospitalized cardiac patients is 10.2%. TD is associated with an increased mortality rate and LOS. Consequently, routine screening for thyroid function in this population is advisable, particularly for selected high-risk subgroups. Future studies are needed to determine whether optimizing thyroid function can improve survival in these patients.

A Cross-Sectional Study of Acute Coronary Syndrome and Thyroid Profile: Dissecting the Relationship to Improve Patient Care

INTRODUCTION

Thyroid-releasing hormones are pivotal in regulating cardiovascular (CVS) function and maintaining its hemodynamics and homeostasis. Even a minor alteration in thyroid function has an enormous implication on CVS morbidity and mortality. Moreover, hypothyroidism was found to be a potential menace for coronary artery disease (CAD). The objective of this study was to determine the role of thyroid-releasing hormones in patients suffering from acute coronary syndrome (ACS).

METHODOLOGY

Among a cohort of 100 patients suffering with ACS, a complete history and clinical information followed by physical examination and electrocardiography were recorded. Blood samples were also collected to record the blood sugar levels i.e., fasting blood sugar (FBS), postprandial blood sugar (PPBS), and thyroid profile, including free thyroid stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and reverse triiodothyronine (rT3). The data was analyzed using SPSS version 26 software (IBM Corp., Armonk, NY, USA).

RESULT

The study identified alterations in the thyroid hormone levels in 27% of patients suffering from ACS. The prevalence of euthyroid sick syndrome was found to be 59.3%, while subclinical hypothyroidism and subclinical hyperthyroidism were reported among 18.5% and 14.8% of patients respectively. There was no significant difference found between males and females. The study illustrated a greater occurrence of aberrant thyroid hormone profiles among those aged 40-60 years. The ST-elevated myocardial infarction (STEMI) group had a statistically significant higher prevalence of an aberrant thyroid hormone profile compared to the non-ST-elevated myocardial infarction (NSTEMI) and unstable angina (UA) groups (p=0.02). A total of nine patients died with ACS and all of those had statistically significant low fT3 and TSH values while higher rT3 values (p<0.05).

CONCLUSION

An atypical thyroid status has been found to elevate the likelihood of developing CAD and experiencing CVS mortality. This condition can impact ventricular function and serum cholesterol levels as well as heart rate and rhythm. Therefore, understanding this relationship could potentially lead to improved treatment strategies for individuals with ACS which will further prevent major CVS complications.

Low-normal free triiodothyronine as a predictor of post-operative atrial fibrillation after surgical coronary revascularization

Background

Recent studies have focused on the association between thyroid function within normal range and cardiovascular diseases, especially on free triiodothyronine (FT3) levels. This study aims to evaluate the effects of normal FT3 level on new-onset atrial fibrillation (AF) in patients with surgical coronary revascularization.

Methods

The patients who underwent surgical coronary revascularization were enrolled in the retrospective study. Thyroid function was tested after an overnight fast on the first morning of hospitalization. Serum FT3 level was divided into quartile groups within the normal range. Hazards ratios (HRs) of FT3 level for AF were analyzed by COX proportional hazard model.

Results

This study included 503 patients with a mean [standard deviation (SD)] age of 63 (±9) years, and 396 (78.73%) were male. Post-operative AF (POAF) occurred in 120 (23.86%) patients at a median of two days after surgical coronary revascularization. The cumulating incidence of AF was significantly higher in the FT3 quartile 1 (Q1) group especially in older patients as evidenced by Kaplan-Meier analysis. Additionally, the patients who experienced AF had longer hospital stays, the same result was also found in the FT3 Q1 group. Further study demonstrated that low-normal FT3 was an independent predictor of POAF [HR =1.52, 95% confidence interval (CI): 1.01, 2.28, P=0.045].

Conclusions

Low-normal FT3 is associated with an increased risk of POAF and is an independent predictor of POAF. Patients who experienced AF have longer hospital stays. The findings may help to identify patients with surgical coronary revascularization at a higher risk for the development of AF.

Prognostic impact of coexisting cardiovascular disease in patients with cancer: A multicenter retrospective cohort study

Background

The incidence of malignancy and cardiovascular disease (CVD) is increasing worldwide. However, it is not entirely clear how the coexistence of CVD at the time of cancer diagnosis affects the overall survival of patients with cancer.

Methods and results

We used the cancer registries and administrative claims data of patients diagnosed with cancer at 36 designated cancer care hospitals in Osaka, Japan, from 2010 to 2015. The Cox proportional hazard model was used to examine how coexisting CVD (heart failure [HF], ischemic heart disease, peripheral arterial disease, cerebrovascular accidents, and atrial fibrillation) affected overall survival and the impact of HF severity, as documented by the New York Heart Association (NYHA) classification. Of the 131,701 patients with cancer, 9704 had coexisting CVD. The 3-year survival rates for patients with and without coexisting CVD were 62.9 % and 77.6 %, respectively. The adjusted hazard ratio (aHR) for all-cause mortality for coexisting CVD was 1.47 (95 % confidence interval, 1.41-1.52). Among the CVD subtype, patients with coexisting HF had the poorest prognosis. The aHRs in patients with HF by NYHA classification, using the patients without HF as a reference, were as follows: Class I: 1.33 (p = 0.217); II: 1.68 (p < 0.001); III: 1.54 (p = 0.011); IV: 2.47 (p < 0.001).

Conclusion

Coexisting CVD and HF severity at cancer diagnosis is associated with survival in patients with cancer.

The hysteresis damage of cold exposure on tissue and transcript levels in mice

OBJECTIVES

Although cold stress-induced damage to the heart and thyroid has been reported, specific organ associations between the heart and thyroid with delayed injury mechanisms have not been investigated. In this study, we determined the damage time and transcript levels of a large number of genes in the heart and thyroid after cold exposure. Meanwhile, we analysed the relationship between heart and thyroid injury in human medical records to determine the association of delayed injury from cold exposure.

METHODS

Mice were exposed to cold stress and hysteresis injury. Gene changes at the transcriptional level were detected using high throughput sequencing technology. The most variable genes were verified at the protein level using Western Blotting and medical records were collected and analysed.

RESULTS

The damage was the most severe when the animals were allowed to recover to room temperature for 4 h after exposure to cold stress. During this process, STAT1 and ATF3 genes were acutely up-regulated. Analysis of human medical records showed the highest correlation between AST and T4 under cold stress (p = 0.0011).

CONCLUSIONS

Exposure to cold increases blood level of free thyroid hormone and biomarkers of myocardial injury, as well as related mRNA levels. These changes were more pronounced after return to room temperature.

Prognostic implications of thyroid disease in patients with atrial fibrillation

Atrial fibrillation (AF) is often accompanied by thyroid disease (THD). This study aimed to explore the relationship between THD and the occurrence of significant clinical outcomes in patients with AF. This post hoc analysis utilized data from the MISOAC-AF trial (NCT02941978), which enrolled hospitalized patients with AF. Patients were categorized based on their THD history into hyperthyroidism, hypothyroidism, or euthyroidism. Cox regression models were employed to calculate unadjusted and adjusted hazard ratios (aHRs). The primary outcomes of interest included all-cause mortality, cardiovascular death, and hospitalizations during the follow-up period. The study included 496 AF patients (mean age 73.09 ± 11.10 years) with available THD data, who were followed-up for a median duration of 31 months. Among them, 16 patients (3.2%) had hyperthyroidism, 141 (28.4%) had hypothyroidism, and 339 (68.4%) had no thyroid disease. Patients with hypothyroidism exhibited higher rates of hospitalization during follow-up (aHR: 1.57, 95% CI 1.12 to 2.20, p = 0.025) compared to the euthyroid group. Elevated levels of thyroid-stimulating hormone (TSH) were correlated with an increased risk of cardiovascular mortality (aHR: 1.03, 95% CI 1.01 to 1.05, p = 0.007) and hospitalizations (aHR: 1.06, 95% CI 1.01 to 1.12, p = 0.03). Conversely, lower levels of triiodothyronine (T3) were associated with higher risks of all-cause mortality (aHR: 0.51, 95% CI 0.31 to 0.82, p = 0.006) and cardiovascular mortality (aHR: 0.42, 95% CI 0.23 to 0.77, p = 0.005). Among patients with AF, hypothyroidism was associated with increased hospitalizations. Furthermore, elevated TSH levels and decreased T3 levels were linked to higher cardiovascular and all-cause mortality risks, respectively.

Global scientific trends on thyroid disease in early 21st century: a bibliometric and visualized analysis

Background

Bibliometrics has been used to analyze the literature in the field of thyroid disease studies in the early 21st century, indicating the changes in current international study trends.

Methods

In this study, a bibliometric analysis of data retrieved from the Web of Science (WoS) database was conducted, and the publication trends and thematic evolution in the field of thyroid disease research from January 1, 2000, to November 16, 2022, were analyzed. A total of 69283 articles related to thyroid diseases were evaluated for their characteristics, including annual publication volume, countries, journals, institutions, authors, keywords, and references. VOSviewer was utilized to perform the analysis of co-authorship, co-citation, co-occurrence and descriptive.

Results

The annual publication volume of thyroid disease research literature showed a fluctuating upward trend from 2000 to 2021, exceeding 5,000 articles for the first time in 2021. The United States (16120 counts, 678255 cities) ranks first in terms of publication volume and citation. Thyroid (n=3201) and Journal of Clinical Endocrinology&Metabolism (n=140399) are the most prolific and cited journals, respectively. The organization with the highest publication volume and citation frequency is Harvard University (1011 counts, 59429 cities), Miyauchi Akira (n=422), Schlumberger, and Martin (n=24839) possess the highest publication volume and citation frequency, respectively. Co-occurrence analysis of 307 keywords with frequencies of more than 20 resulted in 6 clusters (1): Thyroid dysfunction and diseases (2); mechanism of occurrence and development of thyroid cancer (3); autoimmune thyroiditis (4); scope and postoperative management of thyroid surgery (5); fine needle aspiration of thyroid nodules (6); radioactive iodine therapy for thyroid cancer. Active monitoring, thermal ablation, Lenvatinib, and long noncoding RNA refer to the latest keywords. Discussing the six clusters helps scholars to determine the scope and direction of studies.

Conclusion

Over the past two decades, the literature related to thyroid diseases has increased year by year, with closer collaboration between countries, institutions, and authors. In this study, the global trends, research hotspots, emerging subjects, and basic knowledge of literature related to thyroid diseases were respectively elucidated, which will facilitate researchers in this field to seek better development.

Coincident Thyrotoxic Hypokalemic Periodic Paralysis and Cardiomyopathy

Thyrotoxic periodic paralysis (TPP) and thyrotoxic cardiomyopathy (TCMP) are potentially lethal complications of thyrotoxicosis that require emergent recognition and management to attenuate significant morbidity and mortality. We present the case of a 23-year-old Asian male with no prior medical history who developed TPP with coincident TCMP, which was successfully managed with antithyroid and heart failure therapies. The clinician should be aware of the diagnosis and treatment of these 2 life-threatening conditions in a hyperthyroid state.

Hypothyroidism and Cardiovascular Disease: A Review

Hypothyroidism is an endocrine disorder more commonly in older adults. Simultaneously, this population has an increased incidence of cardiovascular risk factors and disease, which remains the leading cause of death worldwide. Thyroid hormones (THs) promote adequate function of the cardiovascular system as they exert their effects through receptors located in the myocardium and the vasculature. In hypothyroidism, this homeostasis is disrupted, which leads to the emergence of pathogenic pathways that accelerate the progression of cardiovascular disease and aggravate its outcomes in these individuals. This article has reviewed existing literature on the relationship between hypothyroidism and cardiovascular disease (CVD). We have explored the pathogenic mechanisms linking both conditions and highlighted the prevalence of cardiovascular risk factors as well as the increased incidence of cardiovascular events in overt and subclinical diseases. Furthermore, indications of hormone replacement therapy in subclinical disease and its efficacy in reducing CVD morbidities in a particular subset of patients have been discussed.

Circulating thyroid hormones and clinical parameters of heart failure in men

Heart failure (HF) is a multiple hormonal deficiency syndrome which includes alterations in the serum concentration of thyroid hormones (TH). This cross-sectional study enrolled 215 male patients hospitalised for acute HF. Data on cardiovascular risk factors, chronic medications, cardiac function assessed by echocardiography, and clinical parameters of HF were prospectively collected. The independent predictive association of TH with all investigated parameters of the HF severity were assessed. The patient's mean age was 74.4 years, 57.2% had arterial hypertension, 54.0% were consuming alcohol, and 42.3% were diabetics. Multivariate analysis revealed that total triiodothyronine (TT3) was an independent predictor of greater left ventricular ejection fraction (LVEF; β = 0.223, p = 0.008), less progressed left ventricular diastolic dysfunction (LVDD; β = - 0.271, p = 0.001) and lower N-terminal pro-brain natriuretic peptide (NT-proBNP; β = - 0.365, p < 0.001). None of the TH other than TT3 was associated with LVDD or NT-proBNP, whereas free triiodothyronine (β = - 0.197, p = 0.004), free thyroxine (β = - 0.223, p = 0.001) and total thyroxine (β = - 0.140, p = 0.041) were inversely associated with LVEF. The present study suggests that, among TH, serum TT3 level is most closely associated with echocardiographic, laboratory and clinical parameters of the severity of HF in men.

Association between the Systemic Immune-Inflammation Index and Thyroid Function in U.S. Adults

Background

The systemic immune-inflammation index (SII) is used as an indicator of prognosis for a wide range of diseases. Thyroid function has been found to be strongly associated with inflammation. The purpose of this investigation was to analyze the correlation between SII and various thyroid functions.

Methods

This study utilized data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012. The association between SII and thyroid function was analyzed using weighted univariate and multivariate linear regression analyses. Subgroup analyses, interaction tests, and weighted restricted cubic spline (RCS) regression analyses were also employed to test this correlation.

Results

Of the 6,875 participants (age ≥ 20 years), the mean age was 46.87 ± 0.40 years. The adjusted model showed that lnSII was negatively correlated with FT3 (β = -0.0559, 95% CI -0.1060 to -0.0059,) and FT3/FT4 (β = -0.0920, 95% CI -0.1667 to -0.0173,). There was a positive correlation between lnSII and TT4 (β = 0.1499, 95% CI 0.0722-0.2276,). In subgroup analyses, lnSII still independently affected a wide range of thyroid functions. Weighted RCS analysis showed a nonlinear relationship between FT3 and lnSII.

Conclusion

Close relationships exist between SII and a variety of thyroid functions. SII can be used as an indicator to predict thyroid dysfunction. Control of inflammatory activity may be a protective measure against thyroid dysfunction. More large-scale prospective studies are necessary to further explore the correlation between SII and thyroid function and the role of obesity in this.

Thyroid Function in Children with Cyanotic and Non-Cyanotic Congenital Heart Disease

OBJECTIVE

Congenital heart disease (CHD) is one of the common diseases of childhood, which is classified into non-cyanotic and cyanotic types. It can affect thyroid function and lead to disruptions in thyroid hormone secretion and hypofunction. This study aimed to evaluate thyroid function in patients younger than 2 years old with cyanotic and non-cyanotic CHD.

MATERIALS AND METHODS

In our study, 101 patients (female/male: 50/51) were included. The thyroid-stimulating hormone and thyroid hormones such as thyroxine (T4) and triiodothyronine (T3) were measured using the electrochemiluminescence method, and thyroid peroxidase antibodies were measured by an enzyme-linked immunosorbent assay. Subclinical hypothyroidism referred to normal levels of T4, with elevated levels of thyroid-stimulating hormone in the serum.

RESULTS

The frequency of subclinical hypothyroidism and hypothyroidism in patients with cyanotic CHD was estimated at 27.5% and 10%, respectively, and 1 patient had hyperthyroidism. The majority of cyanotic and non-cyanotic CHD cases were diagnosed with tetralogy of Fallot (30%) and patent ductus arteriosus (32.79%). There were no significant differences between cyanotic and non-cyanotic groups regarding T3, T4, free T3, free T4, and anti-thyroid peroxidase antibody levels (0.389, 0.142, 0.354, 0.248, and 0.333, respectively).

CONCLUSION

Based on the present findings, subclinical hypothyroidism is a common finding in cyanotic CHD patients during childhood, which is associated with increased levels of oxygen saturation, severity of cyanosis, and age.

The C-Terminal Cross-linked Telopeptide of Type I Collagen (CTX-I) as a Potential Cardiomyopathy Biomarker in Friedreich Ataxia Patients

Friedreich's ataxia (FRDA) is the most common inherited recessive ataxia. Cardiomyopathy (CM) with myocardial hypertrophy is the predominant cause of death. The presence of CM is variable and the risk factors for cardiac involvement are not entirely clear. Markers of collagen degradation, such as C-terminal cross-linked telopeptide of type I collagen (CTX-I), seem to be associated with unfavorable cardiovascular outcomes. The aim of our study was to measure serum CTX-I as a marker of cardiac fibrosis in FRDA patients. We measured serum CTX value in twenty-five FRDA patients (mean age, 31.3 ± 14.7 years) and nineteen healthy controls (mean age, 34.0 ± 13.5 years). Patients underwent echocardiography and SARA scale evaluation. CTX values were significantly higher in the patients than in the control group (31.82 ± 2.27 vs 16.44 ± 1.6 μg/L; p = 0.006). CTX-I was inversely correlated with age (R =  - 0,535; n = 44; p < 0.001). The regression model identified disease duration and TT3 levels to be independent predictors of CTX-I (model R2 = 0.938; intercept - 64.0, p = 0.071; disease duration coefficient =  - 2.34, p = 0.005; TT3 coefficient = 127.17, p = 0.011). CTX-I, a biomarkers of collagen turnover, is elevated in FRDA and should provide complementary information to identify patients with high cardiological risk even if longitudinal studies are needed to define the role of this serologic marker of collagen metabolism in the natural history of cardiomyopathy in FRDA patients.

Cardiovascular outcomes in subclinical thyroid disease: an update

PURPOSE OF REVIEW

Subclinical thyroid disease is defined by a thyroid stimulating hormone (TSH) level outside of the normal range with normal circulating thyroid hormone levels. Excess adverse cardiovascular outcomes have been observed in certain patient populations with subclinical hypothyroidism (SCH) and hyperthyroidism (SCHr). The role of thyroid hormone and antithyroid treatments for subclinical thyroid disease remains debated.

RECENT FINDINGS

Cardiovascular disease appears to be a major mediator of all-cause mortality in patients with SCH, in particular those aged at least 60 years of age. In contrast, pooled clinical trial results did not find that levothyroxine reduced the incidence of cardiovascular events or mortality in this patient population. The association between SCHr and atrial fibrillation is well established; however, a 5-year follow-up of older patients with mild (TSH 0.1-0.4 mIU/l) SCHr found no increased incidence of atrial fibrillation. Separately, SCHr was associated with derangements in endothelial progenitor cell function that may underlie vascular disease independent from effects on cardiac function.

SUMMARY

The impact of treatment of subclinical thyroid disease on cardiovascular outcomes remains uncertain. Additional prospective and trial data are needed to evaluate treatment effects on cardiovascular outcomes in younger populations.

The severity of valvular heart disease in euthyroid individuals is associated with thyroid hormone levels but not with TSH levels

Background

Abnormal thyroid function is a metabolic disorder and can lead to several complications, including cardiovascular diseases. In this study, we aimed to examine the relationship between clinical traits and outcomes and the thyroid hormone level of euthyroid individuals with valvular heart disease (VHD).

Method

The thyroid function was evaluated in 526 euthyroid VHD patients and 155 healthy control people. As well as clinical indicators were collected and analyzed.

Results

No difference in TSH levels (p>0.05) was recorded; however, fT3, TT3, and TT4 levels were lower in the euthyroid VHD patients than in healthy control(4.3 vs 4.63; 1.37 vs 1.48; 97.7 vs 102.09, respectively, all p<0.05), while the fT4 level was higher (12.91 vs 12.35, p<0.05). Moreover, all showed a continuous trend with the change of NYHA grade which does not consist of the incidence of euthyroid sick syndrome(ESS). Further analysis showed that for every 10-fold increase in BNP, fT4 increases by 83%, fT3 decreases by 30%, and TT3 decreases by 12% after being adjusted for other influencing factors. Meanwhile, adjusted fT4 was correlated with multiple worse clinical indicators, which were influenced by age.

Conclusion

Thyroid hormones are widely regulated in VHD patients even with acceptable cardiac function, except for TSH level. And the adjusted fT4 is related to worse clinical indicators and outcomes which are only recorded in patients under 53 years old.

Correlation between Subclinical Hypothyroidism and Metabolic Syndrome: A Retrospective Study

Background

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

Objectives

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

Methods

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

Results

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

Conclusion

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

Transiently impaired endothelial function during thyroid hormone withdrawal in differentiated thyroid cancer patients

Purpose

Endothelial dysfunction, which was associated with chronic hypothyroidism, was an early event in atherosclerosis. Whether short-term hypothyroidism following thyroxine withdrawal during radioiodine (RAI) therapy was associated with endothelial dysfunction in patients with differentiated thyroid cancer (DTC) was unclear. Aim of the study was to assess whether short-term hypothyroidism could impair endothelial function and the accompanied metabolic changes in the whole process of RAI therapy.

Methods

We recruited fifty-one patients who underwent total thyroidectomy surgery and would accept RAI therapy for DTC. We analyzed thyroid function, endothelial function and serum lipids levels of the patients at three time points: the day before thyroxine withdrawal(P₁), the day before ¹³¹I administration(P₂) and 4-6 weeks after RAI therapy(P₃). A high-resolution ultrasound named flow-mediated dilation (FMD) was used to measure endothelial function of the patients.

Results

We analyzed the changes of FMD, thyroid function and lipids at three time points. FMD(P₂) decreased significantly compared to FMD(P₁) (P₁vsP₂, 8.05 ± 1.55vs 7.26 ± 1.50, p<0.001). There was no significant difference between FMD(P₃) and FMD(P₁) after restoring TSH (thyroid stimulating hormone) suppression therapy (P₁ vs P3, 8.05 ± 1.55 vs 7.79 ± 1.38, p=0.146). Among all parameters, the change of low-density lipoprotein (ΔLDL) was the only factor correlated negatively with the change of FMD (ΔFMD) throughout the RAI therapy process (P_1-2, r=-0.326, p=0.020; P_2-3, r=-0.306, p=0.029).

Conclusion

Endothelial function was transiently impaired in DTC patients at short-term hypothyroidism state during the RAI therapy, and immediately returned to the initial state after restoring TSH suppression therapy.

Thyroid Hormone and Heart Failure: Charting Known Pathways for Cardiac Repair/Regeneration

Heart failure affects more than 64 million people worldwide, having a serious impact on their survival and quality of life. Exploring its pathophysiology and molecular bases is an urgent need in order to develop new therapeutic approaches. Thyroid hormone signaling, evolutionarily conserved, controls fundamental biological processes and has a crucial role in development and metabolism. Its active form is L-triiodothyronine, which not only regulates important gene expression by binding to its nuclear receptors, but also has nongenomic actions, controlling crucial intracellular signalings. Stressful stimuli, such as acute myocardial infarction, lead to changes in thyroid hormone signaling, and especially in the relation of the thyroid hormone and its nuclear receptor, which are associated with the reactivation of fetal development programmes, with structural remodeling and phenotypical changes in the cardiomyocytes. The recapitulation of fetal-like features of the signaling may be partially an incomplete effort of the myocardium to recapitulate its developmental program and enable cardiomyocytes to proliferate and finally to regenerate. In this review, we will discuss the experimental and clinical evidence about the role of the thyroid hormone in the recovery of the myocardium in the setting of heart failure with reduced and preserved ejection fraction and its future therapeutic implications.

Subclinical hypothyroidism, outcomes and management guidelines: a narrative review and update of recent literature

Subclinical hypothyroidism (SCH) is diagnosed when serum thyroid stimulation hormone (thyrotropin; TSH) levels are above the reference range, accompanied by levels of free thyroxine within its reference range. The management of SCH remains a diagnostic and therapeutic challenge despite many years of research relating to its epidemiology, aetiology, effectiveness of treatment and safety. European Thyroid Association (ETA) guidelines for the management of SCH were published almost a decade ago. This narrative review summarizes the clinical literature relating to SCH and outcomes since the publication of these guidelines. Clinical evidence emerging during the previous decade generally supports the view that SCH is associated with adverse outcomes to an extent that is intermediate between euthyroidism and overt hypothyroidism although evidence that treatment with thyroid hormone replacement is beneficial is lacking. Accordingly, the rationale for the recommendations for intervention in the ETA guidelines based on the age of the patient, level of serum TSH, symptoms and comorbidities remains valid today.

Analysis of electronic health records from three distinct and large populations reveals high prevalence and biases in the co-administration of drugs known to interact

The co-administration of drugs known to interact has a high impact on morbidity, mortality, and health economics. We study the drug-drug interaction (DDI) phenomenon by analyzing drug administrations from population-wide Electronic Health Records (EHR) in Blumenau (Brazil), Catalonia (Spain), and Indianapolis (USA). Despite very different health care systems and drug availability, we find a common large risk of DDI administration that affected 13 to 20% of patients in these populations. In addition, the increasing risk of DDI as patients age is very similar across all three populations but is not explained solely by higher co-administration rates in the elderly. We also find that women are at higher risk of DDI overall- except for men over 50 years old in Indianapolis. Finally, we show that PPI alternatives to Omeprazole can reduce the number of patients affected by known DDIs by up to 21% in both Blumenau and Catalonia, and 2% in Indianapolis, exemplifying how analysis of EHR data can lead to a significant reduction of DDI and its associated human and economic costs. Although the risk of DDIs increases with age, administration patterns point to a complex phenomenon that cannot be solely explained by polypharmacy and multimorbidity. The lack of safer drug alternatives, particularly for chronic conditions, further overburdens health systems, thus highlighting the need for disruptive drug research.

Effect of thyroid dysfunction on N-terminal pro-B-type natriuretic peptide levels: A systematic review and meta-analysis

Purpose

Thyroid hormones (THs) significantly affect the cardiovascular system. N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a useful biomarker for diagnosing, evaluating, and predicting outcomes in heart failure (HF). This comprehensive review and meta-analysis aimed to investigate the effects of thyroid dysfunction (hypothyroidism and hyperthyroidism) on NT-proBNP levels.

Methods

Two investigators independently searched PubMed, Embase, Cochrane Library, and Web of Science databases for studies published from inception to July 31, 2022, without any restrictions on language.

Results

21 studies were included. In participants without HF, NT-proBNP levels may be elevated in those with overt hyperthyroidism (standardized mean difference [SMD] 2.38, 95% confidence interval [CI]:1.0-3.76). Notably, among patients with preexisting HF, significantly higher NT-proBNP levels were found in patients with overt hyperthyroidism, overt hypothyroidism, or subclinical hypothyroidism than in euthyroid subjects (SMD [95%CI] = 0.31[0.01, 0.62], 0.32[0.08, 0.56], and 0.33[0.21, 0.46], respectively). Seven trials compared NT-proBNP levels in patients with thyroid dysfunction before and after therapy, and significant drops in NT-proBNP levels were observed in patients with hyperthyroidism (SMD [95%CI] = -1.53[-2.50, -0.55]) upon achieving a euthyroid state. In contrast, increased NT-proBNP levels were observed in hypothyroid patients after treatment (SMD [95%CI] = 1.07[0.28, 1.85]).

Conclusion

Thyroid dysfunction can significantly affect NT-proBNP levels, which may change upon achieving a euthyroid state. Notably, the effect of thyroid dysfunction on cardiac function may depend on the underlying cardiac status. Thus, timely recognition and effective treatment of cardiac symptoms in patients with thyroid dysfunction are mandatory because the prognosis of HF may be improved with appropriate treatment of thyroid dysfunction.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42022353700.

Association of multiple blood metals with thyroid function in general adults: A cross-sectional study

INTRODUCTION

Thyroid function has a large impact on humans' metabolism and is affected by iodine levels, but there is a scarcity of studies that elucidate the association between thyroid function and other elements.

METHODS

We performed a cross-sectional study on 1,067 adults to evaluate the associations of the common essential metals with thyroid function in adults living in an iodine-adequate area of China. Serum free thyroxine (FT4), free triiodothyronine (FT3), thyroid stimulating hormone (TSH), and blood metals (zinc, iron, copper, magnesium, manganese, and calcium) were measured. Further, the thyroid hormone sensitivity indexes, FT3:FT4 ratio, and thyrotropin T4 resistance index (TT4RI) were calculated. Linear regression, quantile g-computation, and Bayesian kernel machine regression methods were used to explore the association of metals with thyroid function.

RESULTS

We found that the TSH levels correlated with copper (negative) and zinc (positive). Iron and copper were positively associated with FT3 and FT4 levels, respectively. Iron (positive) and copper (negative) were correlated with the FT3:FT4 ratio. Furthermore, we found that manganese was inversely correlated with TT4RI, while zinc was positively correlated.

DISCUSSION

Our findings suggest that manganese, iron, copper, and zinc levels were strongly correlated with thyroid function, and patients with thyroid disorders are recommended to measure those metals levels.

A Role of Thyroid Hormones in Acute Myocardial Infarction: An Update

The acute coronary syndrome is one of the commonest life-threatening illnesses. It encompasses the clinical spectrum of acute myocardial ischemia and includes unstable angina and acute myocardial infarction both with and without ST segment elevation. The acute coronary syndrome can be attributed to a significant hemodynamic insult that leads to atherosclerosis of the epicardial coronary arteries. The main causative risk factors, such as obesity, smoking, and alcohol intake, increase the burden of acute coronary syndrome. Owing to an increase in the utilization of antioxidants, the antioxidant capacity decreases concerning the scavenging of lipid peroxides. Moreover, the thyroid hormones are important regulators of the expression of cardiac genes, and many of the cardiac manifestations of thyroid dysfunction are associated with alterations in triiodothyronine- mediated gene expression. Cardiovascular signs and symptoms of thyroid disease are among the most acute clinically relevant findings that occur in combination with both hypothyroidism and hyperthyroidism. By understanding the cellular mechanism of the action of thyroid hormones on the heart and cardiovascular system, it is possible to explain rhythm disturbances and alterations in cardiac output, blood pressure, cardiac contractility, and vascular resistance that result from thyroid dysfunction. Oxidative stress is thereby induced, together with a decrease in antioxidant capacity for overcoming oxidative stress, which leads to endothelial dysfunction, subsequent atherosclerosis, and, ultimately, acute myocardial infarction. The implications for the identification of the effects of thyroid disease on acute myocardial infarction include the observation that restoration of normal thyroid function repeatedly reverses abnormalities in cardiovascular hemodynamics.

Reduced Sensitivity to Thyroid Hormones Is Associated With High Remnant Cholesterol Levels in Chinese Euthyroid Adults

CONTEXT

It remains unclear whether the thyroid system could regulate the atherogenic remnant cholesterol (RC) levels in euthyroid status.

OBJECTIVE

We aimed to investigate the relationship between sensitivity to thyroid hormones and RC levels in Chinese euthyroid population.

METHODS

This study included 18 766 euthyroid adults. High RC levels were defined as the upper quartile of RC levels. The thyroid hormone sensitivity indices, including thyroid feedback quantile-based index (TFQI), thyroid-stimulating hormone index (TSHI), thyrotrophic thyroxine resistance index (TT4RI), and free triiodothyronine to free thyroxine (FT3/FT4) ratio were calculated. Linear and binary logistic regression analysis were applied to determine the associations between those composite indices with RC levels by genders.

RESULTS

Both females and males with high RC levels exhibited co-existing higher TSH and FT4 levels. Linear regression analysis revealed that TFQI, TSHI, and TT4RI were positively, while FT3/FT4 ratio levels were negatively associated with serum RC levels. The odds ratios (ORs) (95% CI) for high RC levels were increased with rising TFQI quartiles (Q) [females: Q3 1.41 (1.22-1.63), Q4 1.61 (1.39-1.86); males: Q3 1.25 (1.09-1.45), Q4 1.38 (1.19-1.59), all P for trend < 0.001] after full adjustment, with Q1 as the reference. TSHI and TT4RI yielded similar results. By contrast, the ORs (95% CI) for high RC levels were decreased with increasing FT3/FT4 ratio quartiles in both genders (P for trend < 0.001).

CONCLUSION

In euthyroid adults, reduced sensitivity to thyroid hormones was associated with high RC levels. Our results suggested an additive cardiometabolic risk of euthyroid population with thyroid hormones insensitivity.

Thyroid hormone, cortisol, interleukin-2, and procalcitonin regulate postoperative delirium in acute type A aortic dissection patients

BACKGROUND

We assessed the relationships between levels of preoperative thyroid hormone (TH), cortisol, interleukin-2 (IL-2), and procalcitonin (PCT) and postoperative delirium (POD) in acute type A aortic dissection (ATAAD) patients receiving modified triple-branched stent-graft (MTBSG) implant surgeries.

METHODS

ATAAD patients received MTBSG implant surgeries in our hospital between February 2019 and December 2020 were recruited. We separated them into a POD and non-POD cohort and employed univariable and multivariable regression analysis to establish independent correlations between preoperative THs, cortisol, IL-2, and PCT and POD. In addition, we conducted stratification analyses to examine the link between pre-surgical THs and POD in normal TSH and lower TSH subgroups.

RESULTS

POD occurred in 78 of 224 patients (34.8%). POD patients exhibited markedly reduced preoperative free triiodothyronine (FT3) (P = 0.008) and free thyroxine (FT4) (P = 0.023) levels, while remarkably enhanced preoperative cortisol (P < 0.001), IL-2 (P < 0.001), and PCT (P < 0.001) levels. Based on multivariate regression analysis, reduced preoperative FT3 (P = 0.032), as well as augmented preoperative IL-2 (P = 0.001), cortisol (P < 0.001), and PCT (P = 0.016) were strong stand-alone risk factors for POD. Moreover, subgroup analysis found the association between FT3 (P = 0.029), FT4 (P = 0.042) and POD was both significant in patients with normal TSH levels.

CONCLUSIONS

Reduced preoperative FT3 and elevated preoperative cortisol, IL-2, and PCT were strong indicators of POD in ATAAD patients. Hence, we recommend that the thyroid function, cortisol, PCT, and IL-2 should be evaluated prior to surgery in ATAAD patients.

Endotrophin, a Collagen VI Formation-Derived Peptide, in Heart Failure

BACKGROUND

Endotrophin, a collagen type VI-derived peptide, mediates metabolic dysregulation, inflammation, and fibrosis in animal models, but has not been studied in human heart failure (HF).

METHODS

We examined the association between circulating endotrophin and outcomes in participants suffering from HF with preserved ejection fraction (HFpEF) enrolled in the TOPCAT trial (n=205). Associations were validated in a participant-level meta-analysis (n=810) that included participants with HFpEF from the PHFS study (United States; n=174), PEOPLE cohort (New Zealand; n=168), a randomized trial of vasodilator therapy (United States; n=45), a cohort from Donostia University Hospital and University of Navarra (Spain; n=171), and the TRAINING-HF trial (Spain; n=47). We also assessed associations in HF with reduced ejection fraction in PHFS (n=1,642).

RESULTS

Plasma endotrophin levels at baseline were associated with risk of future death (standardized hazard ratio [HR] = 1.74; 95% confidence interval [CI]=1.36-2.24; P<0.001) and death or HF-related hospital admission (DHFA; standardized HR=2.11; 95% CI= 1.67-2.67; P<0.001) in TOPCAT. Endotrophin improved reclassification and discrimination for these outcomes beyond the MAGGIC risk score and NT-proBNP (N-terminal pro b-type natriuretic peptide). Findings were confirmed in the participant-level meta-analysis. In participants with HF with reduced ejection fraction in PHFS, endotrophin levels were associated with death (standardized HR=1.82; 95% CI=1.66-2.00; P<0.001) and DHFA (standardized HR=1.40; 95% CI=1.31-1.50; P<0.001), but the strength of the latter association was substantially lower than for the MAGGIC risk score (standardized HR=1.93; 95% CI=1.76-2.12) and BNP (standardized HR=1.78; 95% CI=1.66-1.92).

CONCLUSIONS

Circulating endotrophin levels are independently associated with future poor outcomes in patients with HF, particularly in HFpEF. (Funded by Bristol Myers Squibb; Instituto de Salud Carlos III [Spain] and European Regional Development Fund; European Commission CRUCIAL project; and the U.S. National Institutes of Health National Heart, Lung, and Blood Institute.).

Independent Association of Thyroid Dysfunction and Inflammation Predicts Adverse Events in Patients with Heart Failure via Promoting Cell Death

Thyroid dysfunction and inflammation are individually implicated in the increased risk of heart failure. Given the regulatory role of thyroid hormones on immune cells, this study aimed to investigate their joint association in heart failure. Patients with pre-existing heart failure were enrolled when hospitalized between July 2019 and September 2021. Thyroid function and inflammatory markers were measured at the enrollment. The composite of all-cause mortality or rehospitalization for heart failure were studied in the following year. Among 451 participants (mean age 66.1 years, 69.4% male), 141 incident primary endpoints were observed during a median follow-up of 289 days. TT3 and FT3 levels were negatively correlated with BNP levels (r: −0.40, p < 0.001; r: −0.40, p < 0.001, respectively) and NT-proBNP levels (r: −0.39, p < 0.001; r: −0.39, p < 0.001). Multivariate COX regression analysis revealed that FT3 (adjusted HR: 0.677, 95% CI: 0.551−0.832) and NLR (adjusted HR: 1.073, 95% CI: 1.036−1.111) were associated with adverse event, and similar results for TT3 (adjusted HR: 0.320, 95% CI: 0.181−0.565) and NLR (adjusted HR: 1.072, 95% CI: 1.035−1.110). Restricted cubic splines analysis indicated a linear relationship between T3 level and adverse events. Mechanistically, primary cardiomyocytes showed strong resistance to TNF-α induced apoptosis under optimal T3 concentrations, as evidenced by TUNEL staining, flow cytometry analysis, and LDH release assay as well as increased expression of Bcl-2. Thyroid dysfunction and inflammation are independently associated with cardiovascular risk in heart failure patients, which may concurrently contribute to the ongoing cardiomyocyte loss in the disease progression.

Association between thyroid hormone levels and frailty in the community-dwelling oldest-old: a cross-sectional study

BACKGROUND

Changes in thyroid hormone levels are commonly recognized characters among the elderly, which were reported to potentially influence incident frailty. Therefore, we examined the cross-sectional associations of thyroid hormones (THs) with frailty as well as the five components characterizing frailty (fatigue, resistance, ambulation, number of illnesses, and loss of weight) among the oldest-old.

METHODS

Four hundred and eighty-seven community-dwelling oldest-old from a local community in Haidian District, Beijing, participated in our recruitment campaign between April 2019 and May 2020. The primary outcomes were a definitive diagnosis of frailty according to the FRAIL scale (Fatigue, Resistance, Ambulation, Illnesses, Loss of weight) and a positive score for each frailty subdomain. Demographic information (age, sex, marital status, and educational status), comorbidities, and details on the participants' lifestyles were recorded. Serum THs including free triiodothyronin (fT3), triiodothyronine (T3), free thyroxine (fT4), and thyroxine (T4) and thyroid stimulating hormone (TSH) levels were also measured at the beginning of our study. Logistic regressions were conducted to screen for potential risk factors for frailty and its subdomains.

RESULTS

Among the total 487 subjects at enrollment, 60 (12.23%) of them were diagnosed with subclinical hypothyroidism and 110 (22.59%) of the total population scored positive for frailty. Logistic regression analyses adjusted for all potential confounders, showed that frailty was significantly associated with the serum TSH concentration (odds ratio [OR]: 1.06), fT3 concentration (OR: 0.54), and subclinical hypothyroidism score (OR: 2.18). The association between fT4 and frailty was absent in our observational study. The fT3/fT4 ratio characterizing peripheral hormone conversion was also tested to be correlated with frailty.

CONCLUSION

Subclinical hypothyroidism, higher TSH level, lower fT3 level, and decreased fT3/fT4 ratio were all associated with frailty assessed by the FRAIL scale among the community-dwelling oldest-old, suggesting a relevant role of thyroid function in aging. Future longitudinal studies are warranted to determine the casual relationship between thyroid dysfunction and frailty in the oldest-old.

Minor perturbations of thyroid homeostasis and major cardiovascular endpoints—Physiological mechanisms and clinical evidence

It is well established that thyroid dysfunction is linked to an increased risk of cardiovascular morbidity and mortality. The pleiotropic action of thyroid hormones strongly impacts the cardiovascular system and affects both the generation of the normal heart rhythm and arrhythmia. A meta-analysis of published evidence suggests a positive association of FT4 concentration with major adverse cardiovascular end points (MACE), but this association only partially extends to TSH. The risk for cardiovascular death is increased in both subclinical hypothyroidism and subclinical thyrotoxicosis. Several published studies found associations of TSH and FT4 concentrations, respectively, with major cardiovascular endpoints. Both reduced and elevated TSH concentrations predict the cardiovascular risk, and this association extends to TSH gradients within the reference range. Likewise, increased FT4 concentrations, but high-normal FT4 within its reference range as well, herald a poor outcome. These observations translate to a monotonic and sensitive effect of FT4 and a U-shaped relationship between TSH and cardiovascular risk. Up to now, the pathophysiological mechanism of this complex pattern of association is poorly understood. Integrating the available evidence suggests a dual etiology of elevated FT4 concentration, comprising both ensuing primary hypothyroidism and a raised set point of thyroid function, e. g. in the context of psychiatric disease, chronic stress and type 2 allostatic load. Addressing the association between thyroid homeostasis and cardiovascular diseases from a systems perspective could pave the way to new directions of research and a more personalized approach to the treatment of patients with cardiovascular risk.