Effect of Levothyroxine on Left Ventricular Ejection Fraction in Patients With Subclinical Hypothyroidism and Acute Myocardial Infarction: A Randomized Clinical Trial

Efficacy and safety of levothyroxine monotherapy in lowering the risk of cardiovascular disease in older adults with subclinical hypothyroidism: research protocols of a multicenter, open-label, randomized controlled trial

OBJECTIVE

This multicenter, open-label, randomized controlled trial (RCT) aims to assess the efficacy and safety of levothyroxine monotherapy in lowering the risk of cardiovascular disease (CVD) in untreated older adults with subclinical hypothyroidism (SCH) who are diagnosed according to population-specific TSH reference values.

METHODS

A total of 254 patients with SCH who meet the diagnostic criteria will be recruited, and the baseline clinical data of the patients will be collected. Then, a total of 127 patients will be randomly divided into each of the treatment and control groups, and the treatment group will receive daily levothyroxine doses (Merck Euthyrox® levothyroxine 50 mcg tablet). Specifically, 50 µg of levothyroxine per day will be administered to patients in the treatment group (or 25 µg to patients with a body weight < 50 kg) for at least 48 weeks to maintain thyroid-stimulating hormone (TSH) levels within the normal range. The participants in the control group will be subjected only to thyroid status evaluation, and the results will be recorded. The participants will complete five visits before and after the start of the trial, and differences in the change in carotid intima-media thickness (CIMT), maximum mean change in plaque burden, and changes in lipid profiles, bone mineral densities, and incidences of fatal and nonfatal cardiovascular events between the initial visit and the last follow-up visit will be evaluated via vascular ultrasound.

DISCUSSION

We will explicitly address whether levothyroxine replacement therapy provides cardiovascular benefits for older adults with subclinical hypothyroidism.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, No. ChiCTR2400092634. Registered on 30 November 2024. Recruitment for this study began on December 1, 2024, and continues until at least until November 30, 2025.

Dusp14-Mediated Dephosphorylation of MLKL Protects Against Cardiomyocyte Necroptosis in Hypothyroidism-Induced Heart Failure

BACKGROUND

Hypothyroidism leads to multiple organ dysfunction, with the heart the most affected. However, the pathologic mechanism of hypothyroidism-induced heart failure remains to be completely elucidated. Thyroid hormone replacement therapy enhances myocardium systolic function but increases the occurrence of arrythmias. There is an urgent need to explore these mechanisms in detail and to discover and develop drugs that can target and manage heart failure in patients with hypothyroidism.

METHODS

In this study, a mouse model of hypothyroidism-induced heart failure was established through the administration of propylthiouracil. Dusp14 knockout mice were generated, and adeno-associated virus-mediated cardiomyocyte-specific overexpression of Dusp14 (dual specificity phosphatase 14) was used in combination with related cellular experiments to investigate the protective effects of Dusp14 on hypothyroidism-induced heart failure. Further analyses confirmed the crucial involvement of necroptosis in the pathogenesis of hypothyroidism-induced heart failure, and demonstrated the protective role of Dusp14 in modulating necroptosis. In addition, a novel small molecule compound that effectively regulates Dusp14 activity in vitro was identified through molecular docking, providing a potential therapeutic avenue.

RESULTS

Dusp14 regulates necroptosis and mitigates hypothyroidism-induced heart failure. Myocardial tissue sections from mice in the hypothyroidism group showed positive Evans blue dye staining, and the serum levels of the myocardial injury marker lactate dehydrogenase were significantly higher compared with the euthyroid group (n=8). In addition, phosphorylation levels of the necroptosis marker MLKL (mixed lineage kinase domain-like protein) were significantly elevated, indicating the activation of necroptosis (n=8). These findings suggest that myocardial necroptosis is activated during hypothyroidism. Myocardial-specific overexpression of Dusp14 reduced myocardial necroptosis and improved myocardial contractile function in hypothyroid mice (n=8). In contrast, Dusp14 knockout exacerbated myocardial contractile dysfunction and necroptosis in these mice (n=5-7). These results indicate that Dusp14 alleviates hypothyroidism-induced heart failure by inhibiting necroptosis. P077-0472, a small molecule compound, was identified as an activator of Dusp14, which could inhibit cardiomyocyte necroptosis from hypothyroidism (n=6).

CONCLUSIONS

Dusp14 inhibits cardiomyocyte necroptosis from hypothyroidism and consequently rescues damaged cardiomyocytes. P077-0472, a novel small molecule compound that activates the dephosphorylation function of Dusp14, could inhibit cardiomyocyte necroptosis from hypothyroidism.

Triiodothyronine protects infarcted myocardium by reducing apoptosis and preserving mitochondria

Myocardial infarction (MI) is a leading cause of heart failure, with thyroid hormone (TH) signaling playing a key role in heart function and postinfarct recovery. Despite evidence of TH administration's safety in cardiac patients, inconsistent therapeutic outcomes and limited understanding of its mechanisms hinder clinical translation. This study aims to investigate the long-term effect of acute triiodothyronine (T3) administration following MI and to elucidate the mechanisms of its cardioprotective actions. To this end, two doses (40 μg/kg) of T3 were administered immediately after injury and 24 h later in a cryoinjury mouse model of left ventricle (LV) infarction. Remarkably T3 administration significantly reduced scar expansion. Echocardiographic analysis conducted 28 days post-injury revealed that T3 administration improved LV remodeling and prevented LV hypertrophy. At molecular level, T3 administration strongly reduced apoptosis in the peri-infarcted area, without inducing cardiac cell proliferation. Furthermore, T3 prevented the accumulation of long-chain acylcarnitines and the subsequent mitochondrial damage. These findings demonstrate that acute T3 treatment following MI improves long-term LV function and reduces LV remodeling by limiting apoptosis in the peri-infarct region and by preserving mitochondrial function and structural integrity.

Research status of subclinical hypothyroidism promoting the development and progression of cardiovascular diseases

In recent years, the incidence of cardiovascular disease (CVD) has risen steadily, significantly impacting public health. Subclinical hypothyroidism (SCH) remains a controversial risk factor for CVD. This review examines the associations between SCH and dyslipidemia, carotid intima-media thickness (C-IMT), cardiac dysfunction, and cardiovascular event risk. Evidence suggests SCH may exacerbate atherosclerosis and cardiac dysfunction through mechanisms such as increased LDL synthesis, oxidative stress, and impaired vascular endothelial function. However, the causal link between SCH and cardiovascular outcomes remains unclear due to study design heterogeneity and overreliance on TSH levels. Elevated TSH may not solely reflect thyroid dysfunction but could also indicate compensatory responses to inflammation, aging, or stress. Large-scale studies like NHANES and IPD meta-analyses show a strong association between SCH and cardiovascular risk in younger populations, which diminishes in older adults due to physiological TSH increases. The cardiovascular benefits of levothyroxine (L-T4) therapy in SCH patients are limited, especially in older individuals, where a narrow therapeutic window increases side effect risks. Studies relying solely on TSH as a diagnostic and therapeutic target have significant limitations, as TSH cannot distinguish adaptive thyroid adjustments from pathological states and overlooks the role of free thyroid hormones (FT3/FT4). Future research should integrate multi-dimensional markers (such as oxidative stress indicators, vascular elasticity measures, and thyroid antibody status) and adopt longitudinal study designs to more accurately assess the clinical significance of SCH.

The potential value of microRNA-409-5p-mediated negative regulation of USP7 in the diagnosis and treatment of acute myocardial infarction

PURPOSE

This study aimed to explore the effects of ubiquitin-specific peptidase 7 (USP7) on acute myocardial infarction (AMI) and the negative regulation of USP7 by microRNA-409-5p (miR-409-5p).

METHODS

Clinical data were collected from patients admitted to the Cardiology Department of Yan'an Hospital of Kunming City between July 2020 and July 2021. The participants included patients with AMI (AMI; n = 30), stable angina pectoris (SAP; n = 30), and chest pain syndrome (CPS; n = 30) and healthy controls (n = 30). The expression levels of miR-409-5p and USP7 were analysed using Quantitative real-time polymerase chain reaction (qRT‒PCR) and Western blotting (WB). Finally, a dual-luciferase assay was performed to verify the interaction between miR-409-5p and USP7.

RESULTS

The expression level of miR-409-5p was significantly lower (all p < 0.05), whereas the expression level of USP7 was elevated in patients with AMI compared with those in the other three groups (all p < 0.05). A dual-luciferase assay demonstrated that miR-409-5p binds to USP7 3'UTP to inhibit luciferase expression. Compared with cells transfected with mutation fragments and a luciferase reporter vector with microRNA-409-5p mimics and USP7 3'UTR binding and mutation sites, the luminescence level of cells with miR-409-5p was approximately 40% lower. Additionally, miRNA-409-5p was inversely correlated with cTnI (p = 0.004).

CONCLUSION

USP7 plays a significant role in AMI via negative regulation by miR-409-5p. Both miR-409-5p and USP7 hold key potential as early diagnostic biomarkers and therapeutic targets for AMI in the future.

Roles of Autophagy, Mitophagy, and Mitochondria in Left Ventricular Remodeling after Myocardial Infarction

This review examines the mechanisms of left ventricular dysfunction, focusing on the interplay between ventricular remodeling, autophagy, and mitochondrial dysfunction following myocardial infarction. Left ventricular dysfunction directly affects the heart's pumping efficiency and can lead to severe clinical outcomes, including heart failure. After myocardial infarction, the left ventricle may suffer from weakened contractility, diastolic dysfunction, and cardiac remodeling, progressing to heart failure. Thus, this article discusses the pathophysiological processes involved in ventricular remodeling, including the injury and repair of infarcted and non-infarcted myocardia, adaptive changes, and specific changes in left ventricular systolic and diastolic functions. Furthermore, the role of autophagy in maintaining cellular energy homeostasis, clearing dysfunctional mitochondria, and the key role of mitochondrial dysfunction in heart failure is addressed. Finally, this article discusses therapeutic strategies targeting mitochondrial dysfunction and enhancing mitophagy, providing clinicians and researchers with the latest insights and future research directions.

Translating thyroid hormone into clinical practice: lessons learned from the post-hoc analysis on data available from the ThyRepair study

Background

Thyroid hormone (TH) appears to have a reparative action on the postinfarcted myocardium. This novel action was recently tested in a pilot, randomized, double-blind, placebo-controlled trial (ThyRepair). The present study performed a post-hoc analysis of data from the ThyRepair study to provide further insights into the novel actions of TH on the human postischemic myocardium.

Methods

Data from 41 patients participating in the ThyRepair study (n = 20 placebo and n = 21 LT3) were included in the analysis. LT3 treatment started after stenting and continued intravenously for 48 h. All patients had cardiac magnetic resonance (CMR) at hospital discharge; left ventricular (LV) ejection fraction (LVEF%), LV end-diastolic volume index (LVEDVi; mL/m2), LV end-systolic volume index (LVESVi; mL/m2), infarct volume (IV), left ventricular mass index (LVMi) as edema index, and microvascular obstruction (MVO) were assessed. Patients were divided into two groups based on the median value of the IV: patients with IV ≤ 20% of the LV (group A) and patients with IV > 20% (group B). CMR measurements at discharge are expressed as mean ± SD.

Results

In group A, the placebo and T3-treated groups had similar LVEF% (56.8 ± 10.2 vs. 52.2 ± 10.5), LVEDVi (90.9 ± 19.8 vs. 92.8 ± 14.5), and LVESVi (40.8 ± 18.2 vs. 44.9 ± 14.1) at discharge. In group B, LVEDVi and LVESVi were 112 ± 23.8 and 68.3 ± 21.5 for placebo vs. 91.8 ± 18.6 and 49.0 ± 14.0 for the T3-treated group, respectively, p < 0.05. LVEF% was significantly increased in the T3-treated group vs. placebo, 47.3 ± 6.5 vs. 39.9 ± 8.7, p < 0.05. In group B, CMR LVMi was lower in T3-treated patients vs. placebo but did not reach statistical significance (p = 0.1). MVO was 1.95 ± 2.2 in placebo vs. 0.84 ± 0.9 in the LT3-treated group, p = 0.15.

Conclusion

The present study suggests that acute LT3 treatment may exert more favorable effects on the recovery of cardiac function in patients with large infarct size. Furthermore, it signals a potential effect of LT3 on myocardial edema and microvascular obstruction. These novel findings merit further investigation in large trials.

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.

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.

Effects of levothyroxine in subclinical hypothyroidism and heart failure with reduced ejection fraction: An open-label randomized trial

We report a randomized, multicenter, open-label trial (ClinicalTrials.gov: NCT03096613) to investigate the clinical benefits of levothyroxine (L-T4) administration in subclinical hypothyroidism (SCH) patients with heart failure with reduced ejection fraction (HFrEF). Overall, 117 patients were enrolled and received L-T4 plus standard HFrEF treatment (experimental group, N = 57) or standard HFrEF therapy alone (control group, N = 60). The change of 6-min walk test distance in the experimental group was significantly higher than that in the control group at 24 weeks (70.08 ± 85.76 m vs. 27.73 ± 82.00 m, mean difference [95% confidence interval (CI)] 46.90 [12.90, 80.90], p < 0.001). Improvements in New York Heart Association (NYHA) classification (p = 0.033) and thyroid function were significant. Adverse event incidence was similar between groups (risk ratio [95% CI]: 0.942 1.053 (0.424, 2.616); p = 0.628). L-T4 addition to HFrEF treatment improved activity tolerance, NYHA class, and thyroid function within 6 months, suggesting its potential for combined therapy in HFrEF patients with SCH. Future double-blind, placebo-controlled trials should be performed to confirm these results.

Cardiac recovery from pressure overload is not altered by thyroid hormone status in old mice

Introduction

Thyroid hormones (THs) are known to have various effects on the cardiovascular system. However, the impact of TH levels on preexisting cardiac diseases is still unclear. Pressure overload due to arterial hypertension or aortic stenosis and aging are major risk factors for the development of structural and functional abnormalities and subsequent heart failure. Here, we assessed the sensitivity to altered TH levels in aged mice with maladaptive cardiac hypertrophy and cardiac dysfunction induced by transverse aortic constriction (TAC).

Methods

Mice at the age of 12 months underwent TAC and received T4 or anti-thyroid medication in drinking water over the course of 4 weeks after induction of left ventricular pressure overload.

Results

T4 excess or deprivation in older mice had no or only very little impact on cardiac function (fractional shortening), cardiac remodeling (cardiac wall thickness, heart weight, cardiomyocyte size, apoptosis, and interstitial fibrosis), and mortality. This is surprising because T4 excess or deprivation had significantly changed the outcome after TAC in young 8-week-old mice. Comparing the gene expression of deiodinases (Dio) 2 and 3 and TH receptor alpha (TRα) 1 and the dominant-negative acting isoform TRα2 between young and aged mice revealed that aged mice exhibited a higher expression of TRα2 and Dio3, while expression of Dio2 was reduced compared with young mice. These changes in Dio2 and 3 expressions might lead to reduced TH availability in the hearts of 12-month-old mice accompanied by reduced TRα action due to higher TRα2.

Discussion

In summary, our study shows that low and high TH availability have little impact on cardiac function and remodeling in older mice with preexisting pressure-induced cardiac damage. This observation seems to be the result of an altered expression of deiodinases and TRα isoforms, thus suggesting that even though cardiovascular risk is increasing with age, the response to TH stress may be dampened in certain conditions.

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.

Normal thyroid stimulating hormone is associated with all-cause mortality in patients with acute myocardial infarction after percutaneous coronary intervention

BACKGROUND

Circulating thyroid-stimulating hormone (TSH) levels within the normal reference range can affect the cardiovascular system. The present study investigated the prognostic value of normal TSH levels in patients presenting with acute myocardial infarction (AMI) following percutaneous coronary intervention (PCI).

METHODS

Between January 2013 and July 2019, 1240 patients with AMI and normal thyroid function were enrolled and classified according to TSH tertile. The trial endpoint was all-cause mortality. The integrated discrimination index (IDI) and the net reclassification index (NRI) were used to assess the combined predictive values of the TSH levels and the Global Registry of Acute Coronary Events (GRACE) scores.

RESULTS

After a median 44.25-month follow-up, 195 individuals died. Even after covariate adjustment by multivariate Cox regression (HR: 1.56; 95% CI 1.08-2.25; P = 0.017), the patients in the third TSH tertile were at the highest risk of all-cause mortality. A subgroup analysis revealed significant interactions between the TSH levels and the GRACE scores (high risk vs. low/medium risk) (P = 0.019). The addition of the TSH levels to the GRACE scores substantially improved the prediction of all-cause mortality, especially for high-risk patients (NRI = 0.239; IDI = 0.044; C-statistic value range 0.649-0.691; all significant).

CONCLUSIONS

The third TSH tertile is associated with a higher incidence of all-cause mortality than the first TSH tertile in high-risk patients presenting with AMI after PCI.

Right Ventricular Function Indices at Rest and During Exercise in Hyperthyroid Patients: A Cross-sectional Study

Background

Since hyperthyroidism could be associated with right ventricular dysfunction, this study intended to investigate right ventricular (RV) function using strain echocardiography in hyperthyroid patients both at rest and in maximum-stress conditions.

Methods

This cross-sectional study was conducted at Rajaie Cardiovascular Medical and Research Center, Tehran, Iran, from January 2019 to January 2020. All study participants completed a maximum treadmill exercise test, as well as a complete two-dimensional echocardiogram at rest and the peak of stress test. The data were analyzed using SPSS statistical software. The independent samples t test and Mann-Whitney U test were used for numerical, and the Chi square test was used for nominal variables. P<0.05 was considered statistically significant.

Results

The final analysis included 52 participants (26 subjects in each group). In a maximal stress situation, we found that among the RV function indices, RV global longitudinal strain (P=0.0001), systolic strain rate (P=0.0001), diastolic strain rate (P=0.0002), and tricuspid annular plane systolic excursion (P=0.019) were reduced significantly in the hyperthyroid patients compared to the control group. There was also a linear correlation between RV size and thyroid stimulating hormone (TSH) level (P=0.009, r=0.36). Moreover, we found a negative linear correlation between TSH level with maximum stress RV strain and diastolic strain rate (P<0.001).

Conclusion

The findings of the present study revealed a significant change in RV function indices among hyperthyroid patients. Therefore, it highlights the necessity of early diagnosis and treatment of hyperthyroidism, as well as RV function evaluation in these patients.

The Impact of Age- and Sex-Specific Reference Ranges for Serum Thyrotropin and Free Thyroxine on the Diagnosis of Subclinical Thyroid Dysfunction: A Multicenter Study from Japan

Background: Reference ranges for serum thyrotropin (TSH), free thyroxine (fT4), and free triiodothyronine (fT3) established without considering age- and sex-based differences are currently used to evaluate thyroid function. Therefore, we investigated age- and sex-based differences in serum TSH and thyroid hormone levels in euthyroid individuals. Methods: We performed cross-sectional analyses of retrospective data collected from two Japanese institutions. We estimated sex-specific 95% reference ranges for TSH and fT4 according to age strata. Results: We included data from 14,860 participants undergoing screening with a Siemens thyroid testing kit and 8,132 participants undergoing screening with an Abbott kit during annual health check-ups at Takasaki Hidaka Hospital. In addition, 515 participants visiting a specialized thyroid-focused hospital were evaluated using Tosoh kits. The median TSH level of women in their 30s was 1.5 mIU/L (2.5th percentile, 0.5; 97.5th percentile, 4.6) using the Siemens kit, while that of women in their 60s was 1.9 (0.7-7.8) mIU/L. The corresponding levels were lower in men; the age-associated increase was small. The median serum fT4 level of men in their 30s was 1.3 (1.0-1.7) ng/dL and that of men in their 60s was 1.2 (1.0-1.6) ng/dL. These levels gradually but significantly decreased with age. fT4 levels in women were lower than those in men and remained consistent with age. Serum fT3 levels were significantly higher in men than in women and gradually but significantly decreased with age. The Abbott and Tosoh kits showed similar results. When using the Siemens kit, ∼60% (216/358) of women diagnosed with subclinical hypothyroidism using manufacturer-recommended reference ranges had normal results when age- and sex-specific reference ranges were applied, demonstrating the high percentage of overdiagnosis, especially in those aged ≥60 years. Conversely, some middle-aged individuals with normal thyroid function were reassessed and classified as having subclinical hyperthyroidism by age- and sex-specific reference ranges. Conclusions: Age- and sex-specific reference ranges should be used to avoid over- and underdiagnosis of subclinical thyroid dysfunction and appropriate therapies.

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.

Approach to adult patients with primary hypothyroidism in some special situations: a position statement from the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism (SBEM)

Primary hypothyroidism is a common disorder in clinical practice. The management of most cases of hypothyroidism is usually straightforward, but the best approach in some special situations may raise questions among physicians. This position statement was prepared by experts from the Brazilian Society of Endocrinology and Metabolism to guide the management of three special situations, namely, hypothyroidism in the elderly, subclinical hypothyroidism in patients with heart disease, and difficult-to-control hypothyroidism. The authors prepared the present statement after conducting a search on the databases MEDLINE/PubMed, LILACS, and SciELO and selecting articles with the best evidence quality addressing the selected situations. The statement presents information about the current approach to patients in these special situations.

Effect of Levothyroxine Supplementation on the Cardiac Morphology and Function in Patients With Subclinical Hypothyroidism: A Systematic Review and Meta-analysis

CONTEXT

The impact of abnormal thyroid hormone levels on the cardiovascular system has been explored for decades. Recent emerging evidence suggests that subclinical thyroid dysfunction, especially subclinical hypothyroidism (SCH), significantly affects cardiac indices.

OBJECTIVE

We aimed to determine whether levothyroxine (LT4), commonly used to treat hypothyroidism, affects cardiovascular indices in SCH patients.

METHODS

This is a systematic review and meta-analysis. We searched online databases for studies analyzing cardiac morphology and functional changes in SCH patients before and after LT4 supplementation. A total of 294 SCH patients participated and finished the follow-up. The standard mean difference and 95% CI were calculated in fixed or random-effects models. The clinical outcomes analyzed in this study included 18 indicators, mainly covering cardiac morphology, myocardial performance (including various indicators of systolic and diastolic function), mitral wave flow, and systemic vascular resistance.

RESULTS

A total of 11 studies met our search criteria. All studies explicitly mentioned that serum thyrotropin levels decreased to normal at follow-up. Our results suggest that the cardiac output (CO), left ventricular ejection fraction (LVEF), and the ratio of peak E velocity/peak A velocity were all significantly increased after LT4 supplementation compared with the baseline level. However, we found no clear evidence of significant morphological changes in the heart.

CONCLUSION

Judging from the obvious changes in the CO, LVEF, and E/A ratio, LT4 supplementation can effectively improve the cardiac systolic and diastolic dysfunction prevalent in SCH patients. This study provides evidence of the recommendation for LT4 supplementation in adult SCH patients.

Effects of Acute Triiodothyronine Treatment in Patients with Anterior Myocardial Infarction Undergoing Primary Angioplasty: Evidence from a Pilot Randomized Clinical Trial (ThyRepair Study)

Background: Thyroid hormone has a differential action on healthy and ischemic heart. Triiodothyronine (T3) administration improved postischemic cardiac function while it limited apoptosis in experimentally induced ischemia. Thus, the present study investigated the potential effects of acute liothyronine (LT3) treatment in patients with anterior myocardial infarction. Methods: This study is a pilot, randomized, double-blind, placebo-controlled trial (ThyRepair study). We randomized 52 patients and analyzed data from 37 patients (n = 16 placebo and n = 21 LT3), per prespecified per protocol analysis. We excluded three patients who had died of cardiovascular causes (one in placebo and two in LT3 arm), four with small infarct size below a pre-specified threshold (in the placebo arm), and the rest, who lacked follow-up data. LT3 treatment started after stenting as an intravenous (i.v.) bolus injection of 0.8 μg/kg of LT3 followed by a constant infusion of 0.113 μg/kg/h i.v. for 48 hours. All patients had cardiac magnetic resonance (CMR) at hospital discharge and 6 months follow-up. The primary end point was CMR left ventricular (LV) ejection fraction (LVEF) and secondary endpoints were LV volumes, infarct volume (IV), and safety. Results: The CMR LVEF% at 6 months was 53.6 ± 9.5 for the LT3-treated group and 48.6 ± 11 for placebo, p = 0.15. Acute LT3 treatment resulted in a significantly lower LV end-diastolic volume index (92.2 ± 16.8 mL/m² vs. 107.5 ± 22.2, p = 0.022) and LV systolic volume index (47.5 ± 13.9 mL/m² vs. 61.3 ± 21.7, p = 0.024) at hospital discharge, but not at 6 months. There was no statistically significant difference in CMR IV at hospital discharge between the groups (p = 0.24). CMR IV tended to be lower in the LT3-treated group at 6 months (18.7 ± 9.5 vs. 25.9 ± 11.7, in placebo, p = 0.05). Serious, life-threatening events related to LT3 treatment were not observed. A tendency for an increased incidence of atrial fibrillation (AF) was found in the LT3 group during the first 48 hours (19% for T3 group vs. 5% for placebo, p = 0.13). Conclusion: This pilot randomized, placebo-controlled trial study suggests potential favorable effects (acute cardiac dilatation and 6-month IV) as well as potential concerns regarding a higher risk of AF after LT3 administration early after myocardial infarction, which should be tested in a larger scale study.

Three-Dimensional Echocardiography and Coagulation Function Detection in the Prognosis Evaluation of Patients with Acute Myocardial Infarction

This research was aimed at discussing the application value of coagulation function detection and three-dimensional echocardiography in the prognosis evaluation of acute myocardial infarction (AMI) patients. 72 patients with AMI were divided into the recovered group (good recovery) and unrecovered group (poor recovery) according to the results of postoperative ultrasonography. The left ventricular parameters of the patients were detected by three-dimensional ultrasound, and the coagulation function was also detected. The results showed that 3 months after surgery, the regional end-systolic volume (rESV) and regional end-diastolic volume (rEDV) of the left ventricle in the patients were smaller than the measured values 1 week after surgery. The left ventricular regional ejection fraction (rEF) was greater than the value measured 1 week after surgery, and all the differences were statistically significant (P < 0.05). For the end-systolic volume (ESV), end-diastolic volume (EDV), and ejection fraction (EF) (%), the two-dimensional ultrasound results were significantly lower than the three-dimensional ultrasound results, and there were significant differences (P < 0.05). Tmsvle6-Dif% of the recovered patients was 14.99 ± 9.88 and 14.37 ± 9.78 3 months and 6 months after surgery, respectively. These were smaller than 30.91 ± 18.63 and 33.51 ± 17.96 of the unrecovered patients; the differences were of statistical significance (P < 0.05). Tmsvl6-SD% of recovered patients was 3.69 ± 2.47 and 3.61 ± 1.83 3 months and 6 months after surgery, respectively, which were also smaller than 7.38 ± 4.06 and 7.96 ± 2.82 of unrecovered patients, showing statistically significant difference (P < 0.05). The postoperative Tmsvle6-Dif% and Tmsvl6-SD% of the recovered group were lower than those of the unrecovered patients, with the statistically significant differences (P < 0.05). The level of coagulation factors in the recovered group was also significantly lower than that in the unrecovered group with the difference statistically significant (P < 0.05). The results suggested that three-dimensional echocardiography played an important role in the evaluation of cardiac conditions in AMI patients. The level of coagulation factors varied with the AMI condition of patients, and there was an obvious relationship between them, which could provide a reference value for the prognosis evaluation of patients.

Hypothyroidism

Hypothyroidism is the common clinical condition of thyroid hormone deficiency and, if left untreated, can lead to serious adverse health effects on multiple organ systems, with the cardiovascular system as the most robustly studied target. Overt primary hypothyroidism is defined as elevated thyroid-stimulating hormone (TSH) concentration in combination with free thyroxine (fT₄) concentration below the reference range. Subclinical hypothyroidism, commonly considered an early sign of thyroid failure, is defined by elevated TSH concentrations but fT₄ concentrations within the reference range. Hypothyroidism is classified as primary, central or peripheral based on pathology in the thyroid, the pituitary or hypothalamus, or peripheral tissue, respectively. Acquired primary hypothyroidism is the most prevalent form and can be caused by severe iodine deficiency but is more frequently caused by chronic autoimmune thyroiditis in iodine-replete areas. The onset of hypothyroidism is insidious in most cases and symptoms may present relatively late in the disease process. There is a large variation in clinical presentation and the presence of hypothyroid symptoms, especially in pregnancy and in children. Levothyroxine (LT4) is the mainstay of treatment and is one of the most commonly prescribed drugs worldwide. After normalization of TSH and fT₄ concentrations, a considerable proportion of patients treated with LT4 continue to have persistent complaints, compromising quality of life. Further research is needed regarding the appropriateness of currently applied reference ranges and treatment thresholds, particularly in pregnancy, and the potential benefit of LT4/liothyronine combination therapy for thyroid-related symptom relief, patient satisfaction and long-term adverse effects.

Thyroid disorders and cardiovascular manifestations: an update

Cardiovascular disease (CVD) remains the leading cause of death worldwide, representing a major health, social, and economic issue. Thyroid disorders are very common and affect >10% of the adult population in total. The aim of this review is to describe the physiologic role of thyroid hormones on cardiovascular system, to present cardiovascular manifestations in patients with thyroid disorders, emphasizing in molecular mechanisms and biochemical pathways, and to summarize current knowledge of treatment options. Thyroid hormone receptors are located both in myocardium and vessels, and changes in their concentrations affect cardiovascular function. Hyperthyroidism or hypothyroidism, both clinical and subclinical, without the indicated therapeutical management, may contribute to the progression of CVD. According to recent studies, even middle changes in thyroid hormones levels increase cardiovascular mortality from 20% to 80%. In more details, thyroid disorders seem to have serious effects on the cardiovascular system via plenty mechanisms, including dyslipidemia, hypertension, systolic and diastolic myocardial dysfunction, as well endothelial dysfunction. On top of clinical thyroid disorders management, current therapeutics focus on younger patients with subclinical hypothyroidism and elderly patients with subclinical hyperthyroidism.

Triiodothyronine (T3), inflammation and mortality risk in patients with acute myocardial infarction

OBJECTIVES

To study the relationship between serum-free T3 (FT3), C-reactive protein (CRP) and all-cause mortality in patients with acute myocardial infarction (AMI).

DESIGN

Prospective multicentre longitudinal cohort study.

METHODS

Between December 2014 and December 2016, thyroid function and CRP were analysed in AMI (both ST-elevation (STEMI) and non-ST-elevation) patients from the Thyroxine in Acute Myocardial Infarction study. The relationship of FT3 and CRP at baseline with all-cause mortality up to June 2020 was assessed. Mediation analysis was performed to evaluate if CRP mediated the relationship between FT3 and mortality.

RESULTS

In 1919 AMI patients (29.2% women, mean (s.d.) age: 64.2 (12.1) years and 48.7% STEMI) followed over a median (interquartile range) period of 51 (46-58) months, there were 277 (14.4%) deaths. Overall, lower serum FT3 and higher CRP levels were associated with higher risk of mortality. When divided the patients into tertiles based on the levels of FT3 and CRP; the group with the lowest FT3 and highest CRP levels had a 2.5-fold increase in mortality risk (adjusted hazard ratio (95% CI) of 2.48 (1.82-3.16)) compared to the group with the highest FT3 and lowest CRP values. CRP mediated 9.8% (95% CI: 6.1-15.0%) of the relationship between FT3 and mortality.

CONCLUSIONS

In AMI patients, lower serum FT3 levels on admission are associated with a higher mortality risk, which is partly mediated by inflammation. Adequately designed trials to explore the potential benefits of T3 in AMI patients are required.

Subclinical hypothyroidism in older individuals

Subclinical hypothyroidism, which is defined as a thyroid-stimulating hormone concentration higher than the reference range (generally 4·5 mIU/L or higher) with normal free thyroxine concentrations, is frequently found in older individuals. International guidelines differ in recommendations for management of subclinical hypothyroidism in older individuals. We assessed published data during the past decade on the clinical significance and treatment of subclinical hypothyroidism in individuals aged 65 years and older. Meta-analyses, randomised clinical trials, and cohort studies are discussed in this narrative Review. Studies showed no significantly increased incidence in adverse cardiovascular, musculoskeletal, or cognitive outcomes in individuals aged 65 years or older when serum thyroid-stimulating hormone concentration was 4·5-7·0 mIU/L versus a euthyroid group. Moreover, in older individuals with subclinical hypothyroidism, symptoms of hypothyroidism and cardiac and bone parameters did not improve after levothyroxine treatment. These data suggest that treatment with levothyroxine should be considered for individuals aged 65 years or older with subclinical hypothyroidism when thyroid-stimulating hormone concentration is persistently 7 mIU/L or higher and to not initiate treatment with thyroid-stimulating hormone concentrations of less than 7 mIU/L. Levothyroxine doses should be personalised according to age, comorbidities, and life expectancy.

Impact of persistent subclinical hypothyroidism on clinical outcomes in non-ST-segment elevation acute coronary syndrome undergoing percutaneous coronary intervention

BACKGROUND

Data on the association of subclinical hypothyroidism (SCH) with the severity of coronary artery disease and major adverse cardiovascular and cerebral events (MACCE) in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) after percutaneous coronary intervention (PCI) are limited and conflicting.

OBJECTIVE

We established the baseline rate of SCH and followed the trajectory of thyroid-stimulating hormone (TSH) values during and after hospitalisation for PCI for up to six months and determined whether persistent SCH was associated with the severity of coronary artery disease and MACCE in patients with NSTE-ACS after PCI.

DESIGN

Population-based prospective cohort study.

PATIENTS

We included patients with NSTE-ACS who underwent PCI with simple balloon angioplasty or stent implantation for coronary heart disease.

MEASUREMENTS

Thyroid function tests of patients before PCI and 1 day, 1 week, 1 and 6 months after PCI were performed. Cases showing transient SCH were excluded. Patients were divided into two groups based on the results of four TSH tests: 0.27-4.2 mIU/L (n = 1472, 89.7%) and >4.2 mIU/L (n = 170, 10.4%). The risk factors for the severity of coronary artery lesions were estimated using multinomial logistic regression analysis. Univariate and multivariate Cox regression analyses were used to study the relationship between TSH and MACCE.

RESULTS

Among 1642 patients, there were 1070 males (65.2%) and 572 females (34.8%), with an average age of 62.5 ± 9.6 years. SCH patients had a wider range of diseased vessels and a higher number of diseased vessels (p < .05). TSH level was an independent risk factor for moderate [odds ratio (OR) = 1.144, 95% confidence interval (95% CI): 1.057-1.237, p = .001] and severe (OR = 1.131, 95% CI: 1.043-1.226, p = .003) coronary artery lesions. After adjusting for covariates, the risk of MACCE [hazard ratio (HR): 4.067, p < .001], nonfatal myocardial infarction (HR: 14.724, p = .003), and unplanned PCI (HR: 5.028, p < .001) were higher in the SCH group than in the euthyroidism group. There were no significant differences in the incidence of heart failure (HR: 6.012, p = .175), nonfatal stroke (HR: 2.039, p = .302), unplanned coronary artery bypass grafting (CABG) (HR: 1.541, p = .57), or cardiac death (HR: 2.704, p = .375) between the two groups.

CONCLUSIONS

Preoperative TSH levels and changes in thyroid hormone levels several months post-PCI in NSTE-ACS patients are highly significant in practice. Persistent SCH is associated with severe coronary artery lesions and MACCE, and may be a predictor for evaluating the prognosis of PCI-treated NSTE-ACS patients.

A practical contemporary approach to decision-making on subclinical hypothyroidism

Subclinical hypothyroidism (Shypo) is an increasingly frequent condition in common medical practice. Its diagnosis continues to pose a challenge since a series of non-thyroidal and temporary conditions can elevate serum TSH levels. In addition, the consequences of Shypo are still up for debate. Although detrimental cardiovascular effects have been consistently demonstrated in the young, they are less evident in older adults (65-79 years), and even more so in the oldest old (≥80 years). In the absence of evidence of any benefits of treating Shypo in patients' clinical manifestations and unfavorable outcomes, the most effective decision-making approach should include a thorough investigation of the patient's condition integrating all relevant clinical data, such as TSH levels, age, quality of life, comorbidities, cardiovascular risk, safety, and personal preferences. The decision-making process needs to take into account the risk of levothyroxine overtreatment and the resulting adverse consequences, such as reduction of bone mineral density, heart failure, and atrial fibrillation. Hence, current evidence suggests that individuals with TSH > 10 mU/L, who test positive for TPO Ab or are symptomatic may benefit from levothyroxine treatment. However, a more cautious and conservative approach is required in older (≥65 years of age), and oldest-old (≥80 years) patients, particularly those with frailty, in which the risk of treatment can outweigh potential benefits. The latter may benefit from a wait-and-see approach.

The Association between Thyroid-Stimulating Hormone and Long-Term Outcomes in Patients with ST Segment Elevation Myocardial Infarction Treated by Primary Percutaneous Coronary Intervention

Objective

Thyroid hormones are closely related to the cardiovascular system. Our study aimed to explore the impact of admission thyroid-stimulating hormone (TSH) levels on long-term outcomes in patients with acute ST segment elevation myocardial infarction (STEMI) by detailed stratifications of TSH.

Methods

Consecutive STEMI patients admitted to our hospital were divided into four groups: Group 1 (TSH <0.35 mIU/L), Group 2 (TSH 0.35–1.0 mIU/L), Group 3 (TSH 1.0–3.5 mIU/L), and Group 4 (TSH >3.5 mIU/L). The primary endpoint was all-cause mortality during follow-up, and the median follow-up was 2.5 years. Cox proportional hazard regression models were performed to identify the prognostic value of TSH.

Results

A total of 1186 patients were included. Group 4 was presented with higher systolic and diastolic blood pressure (all P < 0.001), and Group 1 had more patients complicated by heart failure (Killip class >I, P = 0.014). During follow-up, 138 deaths occurred. Patients in Group 4 had the worst long-term outcomes (P < 0.001). The cumulative survival in Group 4 was remarkably lower (Log rank P < 0.001), whereas the other three groups were comparable (Log rank P = 0.365). Through Cox regression analysis, only TSH >3.5 mIU/L was identified as an independent risk factor for long-term mortality after STEMI.

Conclusion

Only TSH elevation beyond the normal range was associated with worse long-term prognosis in STEMI patients, while high-normal TSH or reduced TSH did not alter long-term prognosis of STEMI patients. TSH >3.5 mIU/L was an independent risk factor for long-term mortality in STEMI.

Subclinical Hypothyroidism: Prevalence, Health Impact, and Treatment Landscape

Subclinical hypothyroidism (sHypo) is defined as normal serum free thyroid hormone levels coexisting with elevated serum thyroid-stimulating hormone (TSH) levels. sHypo is a common condition observed in clinical practice with several unique features. Its diagnosis should be based on an understanding of geographic and demographic differences in biochemical criteria versus a global reference range for TSH that is based on the 95% confidence interval of a healthy population. During the differential diagnosis, it is important to remember that a considerable proportion of sHypo cases are transient and reversible in nature; the focus is better placed on persistent or progressive forms, which mainly result from chronic autoimmune thyroiditis. Despite significant evidence documenting the health impacts of sHypo, the effects of levothyroxine treatment (LT4-Tx) in patients with sHypo remains controversial, especially in patients with grade 1 sHypo and older adults. Existing evidence suggests that it is reasonable to refrain from immediate LT4-Tx in most patients if they are closely monitored, except in women who are pregnant or in progressive cases. Future research is needed to further characterize the risks and benefits of LT4-Tx in different patient cohorts.

Expert consensus on diagnosis and treatment for elderly with thyroid diseases in China (2021)

In order to improve the diagnosis and treatment of senile thyroid diseases in China and to promote healthy aging, the Endocrine Metabolic Diseases Group of the Chinese Geriatrics Society, and the Thyroid Group of the Chinese Society of Endocrinology jointly drafted the "Expert consensus on diagnosis and treatment for Chinese elderly with thyroid diseases" (referred to as consensus). The Consensus consists of five parts that set 40 recommendations on main clinical issues. The consensus emphasizes clinical focus on the age-related changes of the hypothalamus-pituitary-thyroid axis in the elderly, and it recommends application of comprehensive geriatric assessment to thoroughly evaluate the impact of thyroid diseases and relevant intervention on overall health condition. Meanwhile, it recommends generalization of screening for hypothyroidism during admission to nursing institution or hospital, and routine health check-ups. Furthermore, it develops individualized stratified management on hyperthyroidism, hypothyroidism, thyroid nodules, and differentiated thyroid carcinoma in the elderly distinguished from the youngers, including treatment regimen, control ranges, and flowcharts for diagnosis and treatment. The Consensus will provide the basis for clinical decisions and health management of thyroid diseases in the elderly by geriatrician, endocrinologist, and general practitioners.

Appeared inexplicable disorders of consciousness after general anesthesia tracheal tube drawing in endoscopic tympanoplasty

Background

Disorders of consciousness (DOC) are neurocognitive disorders related to sharp fluctuations of attention and consciousness, while DOC is characterized by significant interindividual differences, rapid development, and a higher lethal rate.

Case information

A 53-year-old female patient underwent general anesthesia with tracheal intubation in otoendoscopic tympanoplasty. The patient suddenly appeared moderate DOC after tracheal tube removal with K+ 3.6 (3.5-5.3 mmol/L). Based on the ancillary testing and routine laboratory workup, the possible causes of DOC, such as general anesthesia drugs and cardio cerebral events, were temporarily excluded. DOC was reversed by intravenous administration of KCl 1 g, with K+ 3.78 mmol/L. On one day after surgery, the patient occurred suddenly DOC again after intravenous guttae of 5% glucose 1000 ml, K+ 3.87 mmol/L, possibly because of her recurrent hypokalemic paralysis (HP) of past medical history. The patient's consciousness gradually improved after effective KCl supplementation therapy.

Conclusion

DOC caused by periodic paralysis (PP) has not been reported, we speculate that hypoactive DOC is closely correlated with normokalemic periodic paralysis (NormoPP) in this case.

Prevalence, predictors and outcomes of thyroid dysfunction in patients with acute myocardial infarction: the ThyrAMI-1 study

PURPOSE

Thyroid dysfunction in patients with cardiac disease is associated with worse outcomes. This study aimed to evaluate the prevalence and analyse predictors and outcomes of thyroid dysfunction in patients presenting with an acute myocardial infarction (AMI).

METHODS

A prospective multicentre observational study of patients recruited from six acute hospitals within the North of England. Consecutive patients without previous thyroid disease presenting with both ST-elevation AMI (STEMI) and non-ST-elevation AMI (NSTEMI) were recruited to the Thyroxine in Acute Myocardial Infarction 1 (ThyrAMI-1) cohort study between December 2014 and 2016. Thyroid profile, standard biochemistry measurements and demographic information were obtained within 12 h of admission to hospital. Multivariable logistic regression analyses were performed to assess the predictors of thyroid dysfunction and Cox proportional hazards analyses were utilised to compare all-cause mortality by categories of thyroid dysfunction up to June 2019.

RESULTS

Of the 1802 participants analysed, 1440 (79.9%) were euthyroid, 312 (17.3%) had subclinical hypothyroidism (SCH), 22 (1.2%) had subclinical hyperthyroidism (SHyper) and 25 (1.3%) had low T3 syndrome (LT3S). Predictors for SCH were increasing age, female sex, higher thyroid peroxidase antibody (TPOAb) levels, higher serum creatinine levels and early morning sampling time (between 00:01-06:00 h). The predictors of SHyper were lower body mass index and afternoon sampling time (between 12:01 and 18:00 h). Predictors of LT3S were increasing age, higher creatinine levels and presence of previous ischaemic heart disease. Compared to the euthyroid group, patients with LT3S had higher all-cause mortality; adjusted hazard ratio (95% CI) of 2.02 (1.03-3.95), p = 0.04, whereas those with SCH and SHyper did not exhibit significantly increased mortality; adjusted hazard ratios (95% CI) of 1.05 (0.74-1.49), p = 0.79 and 0.27 (0.04-1.95), p = 0.19, respectively.

CONCLUSIONS

Thyroid dysfunction is common in AMI patients on admission to hospital and our data provide an understanding regarding which factors might influence thyroid dysfunction in these patients. Furthermore, the negative association between LT3S and increased mortality post-AMI has once again been highlighted by this study. More research is required to assess if treatment of thyroid dysfunction improves clinical outcomes.

An Underdiagnosed Hypothyroidism and Its Clinical Significance in Patients with Advanced Hepatocellular Carcinoma

BACKGROUND

Many systemic therapies for advanced hepatocellular carcinoma (HCC) may cause hypothyroidism; however, in these patients, hypothyroidism prevalence before therapy and its prognostic impact remain unclear.

MATERIALS AND METHODS

We previously established a prospective cohort of patients who received sorafenib as first-line therapy for advanced HCC. No patients had been clinically diagnosed with hypothyroidism before or during sorafenib treatment. We retrospectively determined the levels of thyrotropin and free thyroxine before initiation of systemic therapy. Hypothyroidism was defined as thyrotropin level higher than the upper limit of the normal range. Among patients with hypothyroidism, free thyroxine level less than the lower normal range was defined as overt hypothyroidism, and free thyroxine level within the normal range was defined as subclinical hypothyroidism.

RESULTS

In total, 79 patients were enrolled; of them, 16 (20%) had hypothyroidism (overt hypothyroidism, 10; subclinical hypothyroidism, 6). Patients with hypothyroidism, compared with those without hypothyroidism, were more likely to be older than 65 years (56% vs. 29%, p = .037), have a serum α-fetoprotein level of >400 ng/mL (81% vs. 52%, p = .037), and have a significantly poorer overall survival (OS; median, 5.5 vs. 11.6 months, p = .043). After adjusting for other potential prognostic factors, hypothyroidism remained an independent predictor for poorer OS (hazard ratio, 2.53, p = .018). Patients with overt hypothyroidism and subclinical hypothyroidism exhibited similarly poor OS (p = .768).

CONCLUSION

Underdiagnosis of hypothyroidism in patients with advanced HCC was common. Hypothyroidism, whether overt or subclinical, is associated with poor prognosis of advanced HCC.

IMPLICATIONS FOR PRACTICE

The results of this study showed the underdiagnosis of hypothyroidism in patients with advanced hepatocellular carcinoma (HCC) and its influence on prognosis. These findings implied the importance of thyroid function check before initiation of systemic therapy for patients with advanced HCC.

Best Achievements in Clinical Thyroidology in 2020

This review highlights the most interesting research in thyroidology conducted in 2020. The publications of interest discussed below dealt with the following topics: thyroid dysfunction, risk of thyroid cancer, molecular diagnostics and new therapeutics for thyroid cancer, and thyroid disease in the coronavirus disease 2019 pandemic era.

Levothyroxine for the Treatment of Subclinical Hypothyroidism and Cardiovascular Disease

Subclinical hypothyroidism is a biochemical condition defined by elevated serum thyroid-stimulating hormone levels in the setting of normal levels of the peripheral thyroid hormones, thyroxine and triiodothyronine. Thyroid hormones act on the heart through various mechanisms and subclinical hypothyroidism has been associated with risk factors for cardiovascular disease, such as hypertension and dyslipidemia. In addition, evidence from multiple studies supports an association between subclinical hypothyroidism and cardiovascular disease. However, the use of levothyroxine in subclinical hypothyroidism to reduce cardiovascular disease risk is not clearly beneficial. Treatment with levothyroxine may only provide benefit in certain subgroups, such as patients who are younger or at higher risk of cardiovascular disease. At present, most of the international societal guidelines advise that treatment decisions should be individualized based on patient age, degree of serum thyroid-stimulating hormone (TSH) elevation, symptoms, cardiovascular disease (CVD) risk, and other co-morbidities. Further study in this area is recommended.