Subclinical Hyperthyroidism Is a Risk Factor for Poor Functional Outcome After Ischemic Stroke

Risk Factors for Post-Stroke Depression Following the Lifting of COVID-19 Restrictions

Purpose

Research on post-stroke depression (PSD) following the lifting of coronavirus disease 2019 (COVID-19) restrictions remains sparse. This study aimed to investigate the factors associated with PSD after the easing of COVID-19 restriction measures.

Patients and Methods

This cross-sectional study was conducted with 947 stroke patients (cerebral hemorrhage and cerebral infarction) meeting the inclusion criteria. Participants completed a demographic questionnaire and the Patient Health Questionnaire-9 (PHQ-9). Additionally, data were collected on C-reactive protein (CRP), homocysteine (Hcy), modified Rankin Scale (mRS), stroke site, National Institutes of Health Stroke Scale (NIHSS), thyroid-stimulating hormone (TSH), and the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification. This study assessed correlations between these indices and PSD.

Results

Stroke patients with a PHQ-9 score ≥5 were identified as having PSD, with a prevalence rate of 14.15%. No significant correlation was found between previous COVID-19 infection and PSD. However, multiple regression analysis revealed associations between PSD and the following factors: TSH (OR: 0.87, 95% CI: 0.76-1), CRP levels (OR: 1.01, 95% CI: 1-1.02), family history of stroke (OR: 4.25, 95% CI: 1.66-10.88), migraine history (OR: 8.63, 95% CI: 2.49-29.85), and shorter sleep duration (OR: 0.6, 95% CI: 0.51-0.71) (all P < 0.05).

Conclusion

CRP, family history of stroke, migraine, sleep duration, and TSH are identified as independent risk factors for PSD following the lifting of COVID-19 restrictions.

Association between thyroid hormone levels in the acute stage of stroke and risk of poststroke depression: A meta-analysis

BACKGROUND

Thyroid hormones have been indicated to be associated with depression, but their relationship with poststroke depression (PSD) remains controversial. Therefore, we performed a meta-analysis to explore the correlation between thyroid hormone levels in acute stroke and PSD.

METHODS

We searched databases for eligible studies. Standard mean differences (SMD) and 95% confidence intervals (CI) were applied to evaluate the association among levels of thyroid hormones, including thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4), in acute stroke patients and the risk of PSD.

RESULTS

A total of 13 studies were included in the analysis. Compared to non-PSD patients, PSD patients had remarkably lower serum TSH and FT3 levels (TSH: SMD = -0.59, 95%CI = -1.04 to -.15, p = .009; FT3: SMD = -0.40, 95%CI = -.51 to -.30, p = .000) and higher serum FT4 levels (SMD = 0.33, 95%CI = .07-.59, p = .013). Subgroup analysis showed that there may be a more statistically significant association between FT3 and the risk of PSD compared to TSH and FT4.

CONCLUSIONS

Our results suggested that patients with lower serum TSH and FT3 levels as well as higher serum FT4 levels in the acute stage of stroke may be more susceptible to PSD.

Investigating the Predictive Value of Thyroid Hormone Levels for Stroke Prognosis

Given the expansion of life expectancy, the aging of the population, and the anticipated rise in the number of stroke survivors in Europe with severe neurological consequences in the coming decades, stroke is becoming the most prevalent cause of functional disability. Therefore, the prognosis for a stroke must be timely and precise. Two databases (MEDLINE and Scopus) were searched to identify all relevant studies published between 1 January 2005 and 31 December 2022 that investigated the relationship between thyroid hormone levels and acute stroke severity, mortality, and post-hospital prognosis. Only full-text English-language articles were included. This review includes Thirty articles that were traced and incorporated into the present review. Emerging data regarding the potential predictive value of thyroid hormone levels suggests there may be a correlation between low T3 syndrome, subclinical hypothyroidism, and poor stroke outcome, especially in certain age groups. These findings may prove useful for rehabilitation and therapy planning in clinical practice. Serum thyroid hormone concentration measurement is a non-invasive, relatively harmless, and secure screening test that may be useful for this purpose.

Cardiovascular and Neuronal Consequences of Thyroid Hormones Alterations in the Ischemic Stroke

Ischemic stroke is one of the leading global causes of neurological morbidity and decease. Its etiology depends on multiple events such as cardiac embolism, brain capillaries occlusion and atherosclerosis, which ultimately culminate in blood flow interruption, incurring hypoxia and nutrient deprivation. Thyroid hormones (THs) are pleiotropic modulators of several metabolic pathways, and critically influence different aspects of tissues development. The brain is a key TH target tissue and both hypo- and hyperthyroidism, during embryonic and adult life, are associated with deranged neuronal formation and cognitive functions. Accordingly, increasing pieces of evidence are drawing attention on the consistent relationship between the THs status and the acute cerebral and cardiac diseases. However, the concrete contribution of THs systemic or local alteration to the pathology outcome still needs to be fully addressed. In this review, we aim to summarize the multiple influences that THs exert on the brain and heart patho-physiology, to deepen the reasons for the harmful effects of hypo- and hyperthyroidism on these organs and to provide insights on the intricate relationship between the THs variations and the pathological alterations that take place after the ischemic injury.

Update on subclinical thyroid dysfunction

Subclinical thyroid dysfunction is defined by serum thyroid-stimulating hormone (TSH) levels either greater or less than the reference range with normal thyroxine (T4) concentrations, and consists of subclinical hypothyroidism (SCH) and subclinical hyperthyroidism (SCHyper). For the proper diagnosis of SCH, it is most important to be able to correctly evaluate the serum TSH levels, which have numerous unique characteristics. We also need to be versed in TSH harmonization, which was recently launched world-wide. In this review, we will attempt to determine the best clinical approaches to the treatment of subclinical thyroid dysfunction based on recent guidelines published from several countries and novel findings of several recent large-scale clinical studies.

The Association Between Subclinical Thyroid Dysfunction and Recurrence of Atrial Fibrillation After Catheter Ablation

Objective

The aim of this study was to evaluate the association between subclinical thyroid dysfunction and the recurrence of atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA).

Methods

We examined the association between subclinical thyroid dysfunction and the recurrence of AF at a large university-affiliated cardiac arrhythmia center in China. Data were collected from consecutive patients who underwent RFCA for AF, excluding those with a history of hypothyroidism, hyperthyroidism, or ongoing medical treatment for hypothyroidism or hyperthyroidism, biochemically defined overt thyroid disease, and long-term use of amiodarone before admission. The primary end point was the recurrence of AF in a time-to-event analysis. We compared outcomes in patients who had subclinical hyperthyroidism or hypothyroidism with those who had euthyroid state, using a multivariable Cox model with inverse probability weighting and propensity score matching.

Results

In all, 93 patients were excluded from 435 consecutive patients who underwent RFCA for AF. Of the remaining 342 patients for the analysis, the prevalence of subclinical hyperthyroidism and subclinical hypothyroidism were 26 (7.6%) and 41 (12.0%), respectively; during a median follow-up of 489 days, 91 patients (26.6%) developed a primary end point event. In the main analysis of the multivariable Cox model, only subclinical hyperthyroidism [hazard ratio: 3.07, 95% confidence interval (CI): 1.54–6.14] was associated with an increased risk of end point event after adjusting for potential confounders. However, the association between subclinical hypothyroidism and the end point event was not significant (hazard ratio: 0.66, 95% CI: 0.31–1.43). Results were consistent either in multiple sensitivity analyses or across all subgroups of analysis. Compared with individuals with free triiodothyronine (fT3) in the lowest quintile, those with fT3 in the highest quintile had an HR of 2.23 (95% CI: 1.16–4.28) for recurrence of AF. With the increase of thyroid-stimulating hormone (TSH), a reduction in the risk of recurrence of AF was detected in the adjusted model, and the hazard ratio (HR) per standard deviation (SD) increase was 0.82 (95% CI: 0.68–0.98).

Conclusion

In this retrospective cohort study involving patients who underwent RFCA for AF, patients with subclinical hyperthyroidism were associated with a markedly higher prevalence of recurrence of AF, whereas patients with subclinical hypothyroidism had a similar recurrence rate of AF compared to those with the euthyroid state.

Thyroid Function Affects the Risk of Post-stroke Depression in Patients With Acute Lacunar Stroke

Objective

This study aimed to investigate whether thyroid function profiles are associated with post-stroke depression (PSD) and evaluate the mediation effect of cerebral small vessel disease (cSVD) on the association of thyroid function profiles and PSD in patients with acute ischemic lacunar stroke.

Methods

In this study, 372 patients with confirmed acute ischemic lacunar stroke within 3 days of onset were consecutively recruited. Serum levels of thyroid hormones and thyroid antibodies were detected on admission. Lacunar infarcts, white matter lesions, cerebral microbleeds, and enlarged perivascular spaces were rated using validated scales. The severity of depression was scored with the 24-item Hamilton Depression Scale in the hospital after a week of stroke onset. Multivariate regression was utilized to analyze the association of thyroid function profiles and PSD. Mediation analysis was employed to evaluate the effect of cSVD on the association of thyroid function profiles and PSD.

Results

A total of 87 (23.4%) participants were diagnosed with depression after stroke. Serum thyroid-stimulating hormone (TSH) levels were significantly higher in patients with PSD than in those without PSD, while free triiodothyronine (FT3) and free thyroxine (FT4) were not significantly different between the two groups. After adjusting for potential confounders, serum TSH levels were positively associated with the risk of PSD (OR = 1.228; 95% CI: 1.053–1.431, p = 0.009). A similar association was also found between the total cSVD burden score and PSD (OR = 2.137; 95% CI: 1.634–2.793, p < 0.001). Further mediation analysis indicated that 26.37% of the association between TSH and PSD was mediated by cSVD.

Conclusions

Serum TSH levels on admission can probably predict depression after acute ischemic lacunar stroke.

Elevated Thyroid Autoantibodies Aggravate Stroke Severity in Euthyroidism with Acute Ischemic Stroke

Introduction

Studies have indicated that immune reactions contribute to endothelial dysfunction and atherosclerosis. It is unclear whether thyroid dysfunction or elevated thyroid autoantibodies are associated with atherosclerosis. Therefore, we investigated the influence of thyroid autoimmunity related to elevated thyroid autoantibodies on functional outcome in euthyroidism with acute ischemic stroke (AIS).

Methods

All patients with AIS underwent tests for thyroid function and thyroid antibodies (thyroid peroxidase antibody and thyroglobulin autoantibody). We divided the patients suffering from euthyroidism and AIS into positive thyroid autoantibody and negative thyroid autoantibody groups. Demographic profiles, risk factors, and functional outcomes were compared between the two groups.

Results

Out of the total 422 patients, 50 (11.8%) were included in the positive thyroid autoantibody group. The National Institutes of Health Stroke Scale (NIHSS) score at admission and discharge was higher in the positive thyroid autoantibody group than the negative thyroid autoantibody group (P < 0.05). In addition, there was significant difference in the mortality during hospitalizations between the two groups (P < 0.01).

Conclusion

This study showed that thyroid autoantibodies aggravate stroke severity in euthyroidism with AIS. We speculate that vascular damage related to thyroid autoimmunity may aggravate the increased risk of unfavorable outcomes, independent of thyroid function.

Thyroid Hormone Levels Help to Predict Outcome of Critically Ill Patients Undergoing Early Neurological Rehabilitation

The present study was aimed at examining thyroid hormones and other clinical factors to improve the accuracy of outcome prediction among critically ill patients undergoing early neurological rehabilitation. Patients consecutively admitted to an intensive or intermediate care unit were screened for eligibility. Serum levels of free triiodothyronine (fT3), free thyroxine (fT4), and thyroid-stimulating hormone (TSH) were collected during the first three days after admission. The Glasgow Outcome Scale (GOS) was defined as the primary outcome measure. Thyroid hormone levels and other clinical factors were entered into a binary logistic regression model to predict a good outcome at the end of early rehabilitative treatment. 395 patients (268 males) with a median age of 62 years (IQR = 52 − 76) and a median disease duration of 19 days (IQR = 13 − 28) were included in the study. Most patients (80%) had decreased fT3 values. Patients with low fT3 were admitted earlier to the rehabilitation facility and had more severe impairment upon admission compared to patients with fT3 values within the normal range. Both decreased fT3 and TSH levels were associated with an unfavorable outcome (GOS ≤ 3), but only TSH proved to be an independent predictor in multivariate analyses (OR = 1.11; 95%CI = 1.02 − 1.22). These data suggest that decreased fT3 and TSH levels upon admission may predict an unfavorable outcome at the end of early rehabilitative treatment. Thus, thyroid hormone levels are not only important during acute treatment but also in prolonged critical illness.

Subclinical thyroid dysfunction and autoantibodies in acute ischemic and hemorrhagic stroke patients: relation to long term stroke outcome

Background

Data regarding the relation between both subclinical thyroid dysfunction, thyroid autoantibodies and clinical outcomes in stroke patients are limited. This study aimed to evaluate subclinical thyroid dysfunction and thyroid autoantibodies production in acute stroke patients and their relation to long term stroke outcome. We recruited 138 patients who were subjected to thorough general, neurological examination and brain imaging. Blood samples were collected for measurement of levels of serum thyroid function [free tri-iodothyronine (FT3), free thyroxin (FT4), thyroid stimulating hormone (TSH)], thyroid autoantibodies within 48 h after hospital admission. FT4 and TSH after 1 year were done. The stroke severity was assessed at admission by the National Institutes of Health Stroke Scale (NIHSS). The stroke outcome was assessed at 3 months and after 1 year by the modified Rankin Scale (mRS). We divided the patients into two groups according to thyroid autoantibodies (positive and negative groups).

Results

Subclinical hyperthyroidism was found in 23% of patients, and subclinical hypothyroidism in 10% of patients. Euthyroidism was detected in 67% of patients. 34% patients had positive thyroid autoantibody. Positive thyroid autoantibodies were commonly found in those with subclinical hyperthyroidism (28%), followed by subclinical hypothyroidism (21%) and euthyroidism (14%). 73% and 59% of stroke patients had poor outcomes (mRS was > 2) at 3 months and 1 year respectively with no significant difference between ischemic and hemorrhagic stroke patients. In the positive group final TSH level, NIHSS score at admission, and disability at 1 year were significantly higher compared with the negative group. Poor outcome was significantly associated with higher NIHSS score at admission, positive thyroid autoantibodies, subclinical hyperthyroidism, and atrial fibrillation.

Conclusions

Subclinical thyroid dysfunction could be found in stroke patients with positive thyroid autoantibodies. Subclinical hyperthyroidism and thyroid autoantibodies were associated with a poor outcome at 1 year in first-ever acute stroke patients especially in those presented with atrial fibrillation and higher NIHSS score at admission.

Subarachnoid Hemorrhage Early Brain Edema Score (SEBES) as a radiographic marker of clinically relevant intracranial hypertension and unfavorable outcome after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The severity of early brain edema (EBE) after aneurysm rupture was reported to be strongly associated with the risk of poor outcome after aneurysmal subarachnoid hemorrhage (SAH). Using the recently developed Subarachnoid Hemorrhage Early Brain Edema Score (SEBES), we analyzed the predictors of EBE and its impact on complications related to intracranial pressure (ICP) increase after SAH and on poor outcome.

METHODS

All consecutive SAH cases treated between January 2003 and June 2016 with assessable SEBES were included (n = 745). Data on demographic characteristics, medical history, initial severity of SAH, need for conservative ICP treatment and decompressive craniectomy, occurrence of cerebral infarctions and unfavorable outcome at 6 months (modified Rankin scale score > 2) were collected. Univariable and multivariable analyses were performed.

RESULTS

Younger age (<55 years; adjusted odds ratio [aOR] 3.16, 95% confidence interval [CI] 2.28-4.38), female sex (aOR 1.64, 95% CI 1.16-2.31), poor initial clinical condition (World Federation of Neurosurgical Societies score 4-5; aOR 1.74, 95% CI 1.23-2.46), presence of intracerebral hemorrhage (aOR 1.63, 95% CI 1.12-2.36), hypothyroidism (aOR 0.60, 95% CI 0.37-0.98) and renal comorbidity (aOR 0.29, 95% CI 0.11-0.78) were independently associated with SEBES (scores 3-4). There was an independent association between SEBES 3-4 and the need for conservative ICP treatment (aOR 2.43, 95% CI 1.73-3.42), decompressive craniectomy (aOR 2.68, 95% CI 1.84-3.89), development of cerebral infarcts (aOR 2.24, 95% CI 1.53-3.29) and unfavorable outcome (aOR 1.48, 95% CI 1.0-2.17).

CONCLUSIONS

SEBES is a reliable predictor of ICP-related complications and poor outcome of SAH. Our findings highlight the need for further research of the impact of patients' demographic characteristics and comorbidities on the severity of EBE after SAH.

Triiodothyronine Aggravates Global Cerebral Ischemia-Reperfusion Injury in Mice

Thyroid hormones (THs) have been suggested to play an important role in both physiological and pathological events in the central nervous system. Hypothyroidism, which is characterized by low levels of serum THs, has been associated with aggravation of ischemic neuronal injuries in stroke patients. We hypothesized that administration of T3, the main active form of THs, may attenuate the ischemic neuronal injuries. In mice, global cerebral ischemia (GCI), which is induced by transient occlusion of the bilateral common carotid artery, causes neuronal injuries by inducing neuronal death and activating inflammatory responses after reperfusion in the hippocampus. In this study, we examined the effect of T3 administration on DNA fragmentation induced by neuronal death and the activation of inflammatory cells such as astrocytes and microglia in the hippocampus following GCI. The content of nucleosomes generated by DNA fragmentation in the hippocampus was increased by GCI and further increased by T3 administration. The protein expression levels of glial fibrillary acidic protein (GFAP), an astrocytic marker, and Ionized calcium binding adaptor protein 1 (Iba1), a microglial marker, in the hippocampus were also increased by GCI and further increased by T3 administration. The levels of T3 in both the serum and hippocampus were elevated by T3 administration. Our results indicate that T3 administration aggravates GCI-reperfusion injury in mice. There may be an increased risk of aggravation of ischemic stroke by the excessive elevation of T3 levels during the drug treatment of hypothyroidism.

Prognostic Significance of Stroke-Associated Infection and other Readily Available Parameters in Acute Ischemic Stroke Treated by Intravenous Thrombolysis

OBJECTIVES

The impact of contracting stroke-associate infection (SAI) that requires antibiotic treatment after an acute ischemic stroke (AIS) treated with alteplase remains unclear. We studied the profiles of SAI in patients with AIS treated with alteplase toward identifying predictive factors and prognostic implications at 90 days post-stroke.

METHODS

We analyzed 33 parameters readily available within 24 hours after AIS: demographics, risk factors, and several clinical and biochemical parameters. Outcome measures were mRS ≤ 2 and mortality 90 days post-stroke.

RESULTS

83 (23.6%) of 352 patients developed SAI. Multivariate logistic regression analysis showed that atrial fibrillation, mRS above 0 pre-stroke, lower delta NIHSS (the difference between NIHSS score measured upon admission and 24 hours after later), CRP≥10 mg/L, and elevated WBC count affected SAI risk (model including CRP levels and WBC count) and atrial fibrillation, mRS above 0 pre-stroke, lower delta NIHSS, HT, and elevated fibrinogen levels affected SAI risk (model excluding CRP levels and WBC count). 231 patients (74.1%) had mRS ≤ 2 at day 90. Multivariate logistic regression analysis showed that younger age, no hypertension, mRS=0 pre-stroke, higher delta NIHSS, no HT, no SAI, and CRP<10 mg/L, were associated with mRS≤2 at day 90. 54 (15.3%) patients died within 90 days. Multivariate logistic regression analysis showed that pre-stroke mRS>0, lower delta NIHSS, HT, CRP≥10 mg/L, lower triglyceride levels affected the risk of death within 90 days.

CONCLUSIONS

Several markers available within 24 hours post-stroke were predictive of SAI that requires antibiotic treatment. SAI affects long-term outcome but not mortality.

Role of hyperhomocysteine, thyroid dysfunction and their interaction in ischemic stroke patients with non-valvular atrial fibrillation

The role of hyperhomocysteinemia (HHcy) and thyroid dysfunction in ischemic stroke with non-valvular atrial fibrillation (AF) remains controversial. Till now, the relationship between HHcy and thyroid dysfunction in ischemic stroke with non-valvular AF has not been reported. The aim of this study was to investigate the role and relationship of HHcy and thyroid dysfunction in ischemic stroke patients with non-valvular AF. Seven hundred and seventeen patients with acute ischemic stroke within the first 7 days of symptom onset were consecutively included in this study. Eligible patients were divided into AF group and without AF group. Variables including age, sex, smoke, drink, history of stroke were collected. Levels of homocysteine (Hcy), thyroid-stimulating hormone were evaluated at presentation. Multivariable logistic regression and spearman bivariate correlate analysis were used to evaluate the relationship of HHcy and thyroid dysfunction in ischemic stroke patients with AF. There were 122 patients with AF and 595 patients without AF. Two hundred and eighty-eight (40.2%) patients had HHcy and Three hundred and sixteen (44.1%) patients had thyroid dysfunction. There was significant difference of serum Hcy (P = 0.014) and thyroxine levels (P = 0.002) between patients with and without AF. Furthermore, the difference of serum Hcy (P = 0.007) and thyroxine levels (P = 0.004) between patients with and without AF was also significant in female subgroups. We did not find association between HHcy and thyroid dysfunction in AF group (P = 0.463). In conclusion, both HHcy and thyroid dysfunction were associated with AF in patients with acute ischemic stroke and in female subgroup patients. However, thyroid dysfunction had no relationship with HHcy in ischemic stroke patients with AF.

Transient expression of thyrotropin releasing hormone peptide and mRNA in the rat hippocampus following global cerebral ischemia/reperfusion injury

INTRODUCTION

The role of extra-hypothalamic thyrotropin-releasing hormone (TRH) has been investigated by pharmacological studies using TRH or its analogues and found to produce a wide array of effects in the central nervous system.

METHODS

Immunofluorescence, In situ labeling of DNA (TUNEL), in situ hybridization chain reaction and quantitative real-time polymerase chain reaction were used in this study.

RESULTS

We found that the granular cells of the dentate gyrus expressed transiently a significant amount of TRH-like immunoreactivity and TRH mRNA during the 6-24 h period following global cerebral ischemia/reperfusion injury. TUNEL showed that apoptosis of neurons in the CA1 region occurred from 48 h and almost disappeared at 7 days. TRH administration 30 min before or 24 h after the injury could partially inhibit neuronal loss, and improve the survival of neurons in the CA1 region.

CONCLUSION

These data suggest that endogenous TRH expressed transiently in the dentate gyrus of the hippocampus may play an important role in the survival of neurons during the early stage of ischemia/reperfusion injury and that delayed application of TRH still produced neuroprotection. This delayed application of TRH has a promising therapeutic significance for clinical situations.

The Prevalence and Predictors of Post-Stroke Depression and Anxiety During COVID-19 Pandemic

Introduction

Stroke is associated with a rise in post-stroke depression (PSD) and anxiety (PSA). In this study, we evaluated the impact of COVID-19 pandemic on the rates of PSD and PSA.

Methods

All stroke admissions to two hospitals in Saudi Arabia during two months were prospectively evaluated for PSD and PSA. NIHSS and serum TSH assessed on admission. PSD and PSA were evaluated using Hospital Anxiety and Depression Scale (HADS). Post-stroke disability was assessed by mRS, while social support assessed by Multidimensional Scale of Perceived Social Support (MSPSS).

Results

Among 50 participants (28 males), clinically significant PSD was found in 36%, while PSA in 32%. PSD associated with higher NIHSS (P < 0.001); lower MSPSS (P = 0.003); higher mRS (P = 0.001); and discontinuation of rehabilitation (P = 0.02). PSA was associated with higher TSH (P = 0.01); lower MSPSS (P = 0.03); while discontinuation of rehabilitation was related to less PSA (P = 0.034). Multivariate analysis showed that NIHSS (OR: 1.58, 95% CI: 742–3.37; P = 0.01); and MSPSS score (OR: 0.66, 95% CI: 0.47–0.94; P = 0.002) were associated with PSD; while PSA was related to TSH level (OR: 8.32, 95% CI:1.42–47.23; P = 0.02), and discontinuation of rehabilitation (OR: -0.96, 95% CI: -1.90–0.02; P = 0.04).

Conclusions

Our research shows that the rise in PSD is related to stroke severity and this has not changed significantly during the pandemic; however, PSA showed a noticeable peak. Social deprivation and the lacking levels of rehabilitation related significantly to both.

Thyroid Hormone and Neural Stem Cells: Repair Potential Following Brain and Spinal Cord Injury

Neurodegenerative diseases are characterized by chronic neuronal and/or glial cell loss, while traumatic injury is often accompanied by the acute loss of both. Multipotent neural stem cells (NSCs) in the adult mammalian brain spontaneously proliferate, forming neuronal and glial progenitors that migrate toward lesion sites upon injury. However, they fail to replace neurons and glial cells due to molecular inhibition and the lack of pro-regenerative cues. A major challenge in regenerative biology therefore is to unveil signaling pathways that could override molecular brakes and boost endogenous repair. In physiological conditions, thyroid hormone (TH) acts on NSC commitment in the subventricular zone, and the subgranular zone, the two largest NSC niches in mammals, including humans. Here, we discuss whether TH could have beneficial actions in various pathological contexts too, by evaluating recent data obtained in mammalian models of multiple sclerosis (MS; loss of oligodendroglial cells), Alzheimer’s disease (loss of neuronal cells), stroke and spinal cord injury (neuroglial cell loss). So far, TH has shown promising effects as a stimulator of remyelination in MS models, while its role in NSC-mediated repair in other diseases remains elusive. Disentangling the spatiotemporal aspects of the injury-driven repair response as well as the molecular and cellular mechanisms by which TH acts, could unveil new ways to further exploit its pro-regenerative potential, while TH (ant)agonists with cell type-specific action could provide safer and more target-directed approaches that translate easier to clinical settings.

Incidence and Mortality of Myocardial Infarction and Stroke in Patients with Hyperthyroidism: A Nationwide Cohort Study in Korea

Background: Hyperthyroidism is associated with various cardiovascular risk factors. However, the relationship between hyperthyroidism and myocardial infarction (MI) or stroke has not been fully elucidated; only a few studies have investigated the association of hyperthyroidism with survival after MI or stroke. Methods: We included 59,021 hyperthyroid patients and a control cohort with 1,180,420 age- and sex-matched subjects from the Korean National Health Insurance database. Blood pressure, body mass index (BMI), glucose and cholesterol levels, and smoking history were obtained during National Health screening examination. We compared the incidence of MI, stroke, and survival after cardiovascular events between subjects with hyperthyroidism and the control cohort. Results: Subjects with hyperthyroidism had higher blood pressure, fasting glucose, and smoking rate, but lower cholesterol levels and a lower obesity rate compared with the control cohort. After adjusting these differences, as well as atrial fibrillation, hyperthyroidism was associated with increased risk of MI and ischemic stroke. Adjusted hazard ratios (HRs) for MI and ischemic stroke with hyperthyroidism was 1.16 [95% confidence interval, CI 1.03-1.30] and 1.12 [CI 1.04-1.20], respectively. In age-, sex-, and BMI-stratified analyses, an increased risk of MI and ischemic stroke remained significant in females, the older age group (≥50 years), and nonobese subjects (BMI <25 kg/m²), but not in males, the younger age group (<50 years), and obese subjects (BMI ≥25 kg/m²). The risk of hemorrhagic stroke was not different between subjects with hyperthyroidism and controls. Adjusted HRs for mortality in subjects with hyperthyroidism who developed MI, ischemic stroke, and hemorrhagic stroke were 1.11 ([CI 0.86-1.43], p = 0.44), 0.89 ([CI 0.75-1.05], p = 0.16), and 1.13 ([CI 0.88-1.47], p = 0.34), respectively. Conclusions: Hyperthyroidism is associated with increased risk of MI and ischemic stroke, independent of cardiovascular risk factors. This association is prominent in subjects with age ≥50 years, in females, and in the nonobese group. Hyperthyroidism did not significantly affect the mortality secondary to cardiovascular events.

Thyroid Hormones in the Brain and Their Impact in Recovery Mechanisms After Stroke

Thyroid hormones are of fundamental importance for brain development and essential factors to warrant brain functions throughout life. Their actions are mediated by binding to specific intracellular and membranous receptors regulating genomic and non-genomic mechanisms in neurons and populations of glial cells, respectively. Among others, mechanisms include the regulation of neuronal plasticity processes, stimulation of angiogenesis and neurogenesis as well modulating the dynamics of cytoskeletal elements and intracellular transport processes. These mechanisms overlap with those that have been identified to enhance recovery of lost neurological functions during the first weeks and months after ischemic stroke. Stimulation of thyroid hormone signaling in the postischemic brain might be a promising therapeutic strategy to foster endogenous mechanisms of repair. Several studies have pointed to a significant association between thyroid hormones and outcome after stroke. With this review, we will provide an overview on functions of thyroid hormones in the healthy brain and summarize their mechanisms of action in the developing and adult brain. Also, we compile the major thyroid-modulated molecular pathways in the pathophysiology of ischemic stroke that can enhance recovery, highlighting thyroid hormones as a potential target for therapeutic intervention.

Prognostic value of subclinical thyroid dysfunction in ischemic stroke patients treated with intravenous thrombolysis

Data regarding the association between subclinical thyroid dysfunction and clinical outcomes in ischemic stroke patients with intravenous thrombolysis (IVT) are limited. We aimed to investigate the predictive value of subclinical thyroid dysfunction in END, functional outcome and mortality at 3 months among IVT patients. We prospectively recruited 563 IVT patients from 5 stroke centers in China. Thyroid function status was classified as subclinical hypothyroidism, subclinical hyperthyroidism (SHyper) and euthyroidism. The primary outcome was END, defined as ≥ 4 point in the NIHSS score within 24 h after IVT. Secondary outcomes included 3-month functional outcome and mortality. Of the 563 participants, END occurred in 14.7%, poor outcome in 50.8%, and mortality in 9.4%. SHyper was an independent predictor of END [odd ratio (OR), 4.35; 95% confidence interval [CI], 1.86–9.68, P = 0.003], 3-month poor outcome (OR, 3.24; 95% CI, 1.43–7.33, P = 0.005) and mortality [hazard ratio, 2.78; 95% CI, 1.55–5.36, P = 0.003]. Subgroup analysis showed that there was no significant relationship between SHyper and clinical outcomes in IVT patients with endovascular therapy. In summary, SHyper is associated with increased risk of END, and poor outcome and mortality at 3 months in IVT patients without endovascular therapy.

Subclinical Hyperthyroidism Could Predict Poor Outcomes in Patients With Acute Ischemic Stroke Treated With Reperfusion Therapy

Background: Evidence for the effect of subclinical thyroid dysfunction on the prognosis of patients suffering from acute ischemic stroke and receiving reperfusion therapy remains controversial. We aimed to investigate the association between subclinical thyroid dysfunction and the outcomes of patients with acute ischemic stroke who were treated with reperfusion therapy.

Methods: One hundred fifty-six consecutively recruited patients with acute ischemic stroke receiving reperfusion therapy (intravenous thrombolysis, intraarterial thrombectomy and combined intravenous thrombolysis and intraarterial thrombectomy) were included in this prospective observational study. We divided patients with subclinical thyroid dysfunction into the following 2 groups and defined a euthyroid group: subclinical hyperthyroidism (a thyroid-stimulating hormone level <0.35 μU/mL), subclinical hypothyroidism (a thyroid-stimulating hormone level >4.94 μU/mL), and a euthyroid state (0.35 μU/mL ≤ thyroid-stimulating hormone level ≤ 4.94 μU/mL). Patients with overt thyroid dysfunction were excluded. The primary outcome was functional disability at 3 months (modified Rankin Scale, mRS), and the secondary outcome was successful reperfusion. A multivariate analysis was performed to evaluate the associations between subclinical thyroid dysfunction and the primary and secondary outcomes.

Results: The subclinical hyperthyroidism group appeared to have poor functional outcomes, but the differences were not significant. However, compared with patients in the euthyroid state, patients with subclinical hyperthyroidism had an increased risk of poor functional outcomes at 3 months after a stroke (adjusted odds ratio [OR] 2.50, 95% confidence interval [CI] 1.01–6.14 for a mRS score of 3 to 6) and a decreased rate of successful reperfusion after reperfusion therapy (OR 0.13, 95% CI 0.04–0.43).

Conclusion: Subclinical hyperthyroidism may be independently associated with a poor prognosis at 3 months and unsuccessful reperfusion in patients with acute ischemic stroke receiving reperfusion therapy.

Depressed TSH level as a predictor of poststroke fatigue in patients with acute ischemic stroke

Objective

To investigate whether thyroid function profiles can predict poststroke fatigue (PSF) in patients with acute ischemic stroke.

Methods

Patients with stroke were consecutively recruited within 3 days of onset in Jinling Hospital. Serum levels of thyroid hormones, thyroid antibodies, hematologic indexes, and biochemical indexes were measured on admission. Fatigue was scored using the Fatigue Severity Scale. Associations were analyzed with multivariate regression and restricted cubic splines.

Results

Of the 704 patients with stroke, 292 (41.5%) were diagnosed with fatigue in the acute stage and 224 (35.3%) 6 months after the index stroke. The serum levels of thyroid-stimulating hormone (TSH) were inversely associated with the risk of PSF in both the acute phase and at follow-up evaluations after adjusting for potential confounders (odds ratio 0.30, 95% confidence interval 0.24–0.37 in the acute phase, and odds ratio 0.70, 95% confidence interval 0.58–0.84 at follow-up). The subgroup analysis indicated that in the acute phase of ischemic stroke, TSH was associated with severity of PSF in the groups with euthyroidism (β = −0.70, p < 0.001), subclinical hypothyroidism (β = −0.44, p < 0.001), and low-T3 syndrome (β = −0.34, p = 0.008). Higher TSH was associated with better Fatigue Severity Scale scores in patients with low-T3 syndrome 6 months after the index stroke (β = −0.35, p = 0.01). Furthermore, in the group with low-T3 syndrome, FT3 serum level could also indicate a higher risk of PSF (β = −2.54, p < 0.001 in the acute phase, and β = −2.67, p < 0.001 at follow-up).

Conclusion

Thyroid function profiles may predict fatigue after acute ischemic stroke, suggesting that neuroendocrine responses could have a role in PSF.

Reverse triiodothyronine (rT3) attenuates ischemia-reperfusion injury

Hypothyroidism has been associated with better recovery from cerebral ischemia-reperfusion (IR) injury in humans. However, any therapeutic advantage of inducing hypothyroidism for mitigating IR injury without invoking the adverse effect of whole body hypothyroidism remains a challenge. We hypothesize that a deiodinase II (D2) inhibitor reverse triiodothyronine (rT3) may render brain specific hypometabolic state to ensue reduced damage during an acute phase of cerebral ischemia without affecting circulating thyroid hormone levels. Preclinical efficacy of rT3 as a neuroprotective agent was determined in rat model of middle cerebral artery occlusion (MCAO) induced cerebral IR and in oxygen glucose deprivation/reoxygenation (OGD/R) model in vitro. rT3 administration in rats significantly reduced neuronal injury markers, infarct size and neurological deficit upon ischemic insult. Similarly, rT3 increased cellular survival in primary cerebral neurons under OGD/R stress. Based on our results from both in vivo as well as in vitro models of ischemia reperfusion injury we propose rT3 as a novel therapeutic agent in reducing neuronal damage and improving stroke outcome.

Stroke in a Young Man Secondary to Paroxysmal Atrial Fibrillation and Thyrotoxicosis: A Case Report

We report a case of a male patient with stroke caused by atrial fibrillation (AF) due to thyrotoxicosis. At hospital admission, he presented hypertension and AF. Magnetic resonance imaging confirmed a right-side ischemic area. The thyrotoxicosis was confirmed by thyroid function and thyroid scintigraphy that showed goiter with diffuse hypercaptation. The patient was treated with tapazole and total thyroidectomy, and pathological findings suggested Graves' disease. Hyperthyroidism is associated with increased supraventricular ectopic activity in patients with a normal heart, and may be an important causal link between hyperthyroidism and AF. The patient experienced significant clinical improvement, but presented long-term neuropsychiatric disorders.

Low free triiodothyronine levels predict symptomatic intracranial hemorrhage and worse short-term outcome of thrombolysis in patients with acute ischemia stroke

The aim of the study was to determine whether thyroid hormones level on admission in patients with ischemic stroke, treated with intravenous recombinant tissue type plasminogen activator (rtPA), was associated with symptomatic intracranial hemorrhage (sICH) and worse outcomes at 3 months.Patients with acute ischemic stroke (AIS) receiving intravenous rtPA thrombolytic treatment on our stroke unit between January 2015 and June 2016 were included in this study. Serum-free triiodothyronine (fT3), free thyroxine (fT4), total triiodothyronine (tT3), total thyroxine (tT4), and thyroid-stimulating hormone (TSH) were detected on admission. The endpoints were sICH, and poor functional outcomes at 3 and 6 months.In all, 159 patients (106 males; mean age 65.36 ± 10.02 years) were included. FT3 was independently associated with sICH (odds ratio [OR] 0.204, 95% confidence interval [CI] 0.065-0.642) and poor outcomes at 3 months (OR 0.396, 95% CI 0.180-1.764). The cut-off values of fT3 for sICH was 3.54 pg/mL (sensitivity 83%; specificity 83%; area under the curve 0.88). FT3 values ≤3.54 pg/mL increased risk for sICH by 3.16-fold (95% CI 0.75-1.0) compared with fT3 values >3.54 pg/mL.Low fT3 levels at admission were independently associated with sICH and worse outcomes at 3 months in AIS patients receiving rtPA thrombolytic therapy.

Ischemic Stroke and Impact of Thyroid Profile at Presentation: A Systematic Review and Meta-analysis of Observational Studies

BACKGROUND

Stroke is the fifth leading cause of mortality in the United States and a leading cause of disability. A complex relationship between thyroid hormone levels and severity of, and outcome after, stroke has been described.

AIM

Our objective is to identify the association between baseline thyroid function profile and outcome after acute ischemic stroke.

METHODS

Studies looking at the association between thyroid function and functional stroke outcomes were identified from available electronic databases from inception to December 16, 2016. Study-specific risk ratios were extracted and combined with a random effects model meta-analysis.

RESULTS

In the analysis of 12 studies with 5218 patients, we found that subclinical hypothyroidism was associated with better modified Rankin scale scores at 1 and 3 months (odds ratio [OR] 2.58, 95% confidence interval [CI] 1.13-5.91, P = .03 and OR 2.28, 95% CI 1.13-3.91, P = .003, respectively) compared with the euthyroid cases. Likewise, patients with higher initial thyrotropin-releasing hormone (TSH) and fT3 or T3 levels had favorable outcomes at discharge (mean differences of TSH .12 [95% CI .03-.22, P = .009] and of fT3 .36 (CI .20-.53, P < .0001]) and at 3 months (mean differences of TSH .25 [95% CI .03-.47, P = .03] and of T3 8.60 [CI 4.58-12.61, P < .0001]).

CONCLUSIONS

Elevated initial TSH (clinical or subclinical hypothyroidism) may correspond to better functional outcomes, whereas low initial T3/fT3 might correlate with worse outcomes in acute ischemic stroke among clinically euthyroid patients. This complex relation merits further well-designed investigations. Whether correcting thyroid profile with hormone supplementation or antagonism may lead to improved outcomes will require large, prospective, interventional studies.

The Impact of Homocysteine, Vitamin B12, and Vitamin D Levels on Functional Outcome after First-Ever Ischaemic Stroke

We explored the relationship between acute ischaemic stroke (IS) early functional outcome and serum levels of homocysteine, vitamin B12, and D in a noninterventional prospective clinical study. We enrolled 50 patients with first-ever IS and performed laboratory tests and functional assessment at three time points: on admission and three and six months after stroke. Modified Rankin Scale (mRS), NIHSS scale, and Barthel index (BI) scores were assessed in all participants by trained examiner blinded to laboratory data. Patients did not receive treatment that might alter laboratory data. Admission NIHSS correlated with homocysteine levels (r = 0.304, p < 0.05), B12 level (r = −0.410, p < 0.01), and vitamin D levels (r = −0.465, p < 0.01). Functional outcome measures (BI and mRS) did not significantly correlate with homocysteine and vitamin D3 levels at 3 and 6 months. However, a positive correlation with vitamin B12 levels was detected for BI both at 3 and 6 months and mRS at 6 months. Higher serum vitamin B12 levels were associated with better functional outcome at follow-up.

The Effects of Altered Membrane Cholesterol Levels on Sodium Pump Activity in Subclinical Hypothyroidism

BACKGROUND

Metabolic dysfunctions characteristic of overt hypothyroidism (OH) start at the early stage of subclinical hypothyroidism (SCH). Na⁺/K⁺-ATPase (the sodium pump) is a transmembrane enzyme that plays a vital role in cellular activities in combination with membrane lipids. We evaluated the effects of early changes in thyroid hormone and membrane cholesterol on sodium pump activity in SCH and OH patients.

METHODS

In 32 SCH patients, 35 OH patients, and 34 euthyroid patients, sodium pump activity and cholesterol levels in red blood cell membranes were measured. Serum thyroxine (T₄) and thyroid stimulating hormone (TSH) levels were measured using enzyme-linked immunosorbent assays. Differences in their mean values were analysed using post hoc analysis of variance. We assessed the dependence of the sodium pump on other metabolites by multiple regression analysis.

RESULTS

Sodium pump activity and membrane cholesterol were lower in both hypothyroid groups than in control group, OH group exhibiting lower values than SCH group. In SCH group, sodium pump activity showed a significant direct dependence on membrane cholesterol with an inverse relationship with serum TSH levels. In OH group, sodium pump activity depended directly on membrane cholesterol and serum T₄ levels. No dependence on serum cholesterol was observed in either case.

CONCLUSION

Despite the presence of elevated serum cholesterol in hypothyroidism, membrane cholesterol contributed significantly to maintain sodium pump activity in the cells. A critical reduction in membrane cholesterol levels heralds compromised enzyme activity, even in the early stage of hypothyroidism, and this can be predicted by elevated TSH levels alone, without any evident clinical manifestations.

Cerebral Ischemia/Reperfusion Injury in the Hyperthyroid Rat

BACKGROUND

Hyperthyroidism as a risk factor for stroke is not conclusive. There are no definite data on the relationship between ischemic cerebrovascular injury and hyperthyroidism. This study was designed to define whether the outcomes of post-ischemic stroke injury are influenced by chronic hyperthyroidism.

METHODS

Two groups of hyperthyroid (HT) and control euthyroid rats of equal numbers (n=22) were included in the study. Hyperthyroidism was induced for 4 weeks by adding L-thyroxine (300 μg/kg) to drinking water. The middle cerebral artery occlusion technique was used to induce focal cerebral ischemia. Neurological disability (neurological deficit score [NDS]) was evaluated after 24 hours, and the rats were sacrificed to obtain their brain. Triphenyl Tetrazolium Chloride (TTC) staining and Evans Blue (EB) extravasation were used to quantify cerebral infarct volume and cerebrovascular integrity disruption. Data analysis was done using SPSS, version 21.

RESULTS

Thyroid hormones levels, T₃ (314±7 vs. 198±3 ng/dL;P=0.001) and T₄ (9.8±0.3 vs. 3.08±0.07 μg/dL;P=0.001), were significantly higher in the HT group than in the controls. Furthermore, most clinical signs seen in hyperthyroid patients were also present in the HT group. Comparison of the data on cerebral ischemia between the HT and control groups showed significant increases in the NDS (2.76±0.16 vs. 2.23±0.09;P=0.03), cerebral infarct volume (479±12 vs. 266±17 mm³;P=0.001), and EB extravasation (50.08±2.4 vs. 32.6±1.2 μg/g;P=0.001) in the former group.

CONCLUSION

The intensified cerebral infarct size and cerebrovascular integrity disruption suggested that chronic hyperthyroidism aggravated post-stroke injury in the rats. More investigation is required to analyze the pathological mechanisms underlying the association between cerebrovascular disease and hyperthyroidism.

Thyroid hormones and functional outcomes after ischemic stroke

Background

Stroke is the fifth leading cause of death and the primary cause of long-term adult disability in the United States. Increasing evidence suggests that low T3 levels immediately following acute ischemic stroke are associated with greater stroke severity, higher mortality rates, and poorer functional outcomes. Prognosis is also poor in critically ill hospitalized patients who have non-thyroidal illness syndrome (NTIS), where T3 levels are low, but TSH is normal. However, data regarding the association between TSH levels and functional outcomes are contradictory. Thus, this study investigated the role of TSH on stroke outcomes, concomitantly with T3 and T4.

Findings

In this work, blood was collected from patients with radiologically confirmed acute ischemic stroke at 24±6 hours post-symptom onset and serum levels of TSH, free T3, and free T4 were measured. Stroke outcomes were measured at discharge, 3 and 12 months using the modified Rankin scale and modified Barthel Index as markers of disability. Though we found that lower levels of free T3 were associated with worse prognosis at hospital discharge, and at 3 and 12 months post-stroke, none of these outcomes held after multivariate analysis. Thus, it is likely that thyroid hormones are associated with other factors that impact stroke outcomes, such as sex, age and stroke etiology.

Conclusions

This study found that lower levels of free T3 were associated with poorer outcomes at hospital discharge, and at 3 and 12 months post stroke, however, these associations diminished after correction for other known predictors of stroke outcome. Thyroid hormones have a complex relationship with ischemic stroke and stroke recovery, which merits further larger investigations.

Alopecia Areata Increases the Risk of Stroke: a 3-year Follow-Up Study

The risk for stroke in alopecia areata (AA) patients is still unknown. This study aimed to investigate the risk for subsequent risk of a stroke in AA patients in a large-scale retrospective cohort study. We identified 3231 patients with AA included in the study group from 2004 to 2011 in the “Longitudinal Health Insurance Database 2000” in Taiwan. We randomly selected 16,155 matched patients as the comparison group. We individually tracked each patient for a 3-year period to identify patients who had received a diagnosis of stroke during the follow-up period. We found that incidence rates of stroke during the 3-year follow-up periods were 5.44 (95% confidence interval (CI) = 4.03 ~ 7.20) and 2.75 (95% CI = 2.30 ~ 3.27) per 1000 person-years for patients with and those without AA, respectively. Cox proportional hazard regressions showed that the adjusted hazard ratio for stroke for those patients with AA was 1.61 (95% CI = 1.13 ~ 2.30) within the follow-up period compared to the controls. We concluded that patients with AA were associated with a higher risk of stroke in the 3-year follow-up period.

Anti-edema action of thyroid hormone in MCAO model of ischemic brain stroke: Possible association with AQP4 modulation

The use of neuroprotective strategies to mitigate the fatal consequences of ischemic brain stroke is a focus of robust research activity. We have previously demonstrated that thyroid hormone (T3; 3,3',5-triiodo-l-thyronine) possesses neuroprotective and anti-edema activity in pre-stroke treatment regimens when administered as a solution or as a nanoparticle formulation. In this study we have extended our evaluation of thyroid hormone use in animal models of brain stroke. We have used both transient middle cerebral artery occlusion (t-MCAO) and permanent (p-MCAO) models of ischemic brain stroke. A significant reduction of tissue infarction and a concurrent decrease in edema were observed in the t-MCAO model of brain stroke. However, no benefit of T3 was observed in p-MCAO stroke setting. Significant improvement of neurological outcomes was observed upon T3 treatment in t-MCAO mice. Further, we tested T2 (3,5-diiodo-l-thyronine) a natural deiodination metabolite of T3 in MCAO model of brain stroke. T2 potently decreased infarct size as well as edema formation. Additionally, we report here that T3 suppresses the expression of aquaporin-4 (AQP4) water channels which could be a likely mechanism of its anti-edema activity. Our studies provide evidence to stimulate clinical development of thyroid hormones for use in ischemic brain stroke.

Subclinical hypothyroidism in addition to common risk scores for prediction of cardiovascular disease: a 10-year community-based cohort study

OBJECTIVE

This study was carried out to determine whether serum TSH levels improve the prediction of cardiovascular risk in addition to common clinical risk scores, given the association between subclinical hypothyroidism (SCH) and cardiovascular disease (CVD).

DESIGN

We carried out an observational study in a prospective cohort.

METHODS

The study included a total of 344 SCH and 2624 euthyroid participants aged over 40 years and who were without previously recorded CVDs were included in this study analysis. We measured thyroid function and traditional risk factors at baseline and estimated the 10-year cumulative incidence of CVD in a gender-stratified analysis.

RESULTS

During 10 years of follow-up, 251 incident cardiovascular events were recorded. The elevation of serum TSH levels significantly increased the CV risk independent of conventional risk factors in men. In the atherosclerotic CVD (ASCVD) risk score or the Reynolds risk score (RRS) model, the addition of serum TSH levels had no effect on model discrimination as measured by the area under the curve in either women or men. Adding serum TSH did not improve the net reclassification improvement in either women (3.48% (P=0.29) in the ASCVD, -0.89% (P=0.75) in the RRS, respectively) or men (-1.12% (P=0.69), 3.45% (P=0.20), respectively) and only mildly affected the integrated discrimination Improvement in the ASCVD-adjusted model (0.30% in women and 0.42% in men, both P=0.05).

CONCLUSIONS

In the context of common risk scoring models, the additional assessment of serum TSH levels provided little incremental benefit for the prediction of CV risk.

Thyroid-stimulating hormone, white matter hyperintensities, and functional outcome in acute ischemic stroke patients

Background

Thyroid-stimulating hormone (TSH) concentrations are frequently altered in acute ischemic stroke patients. It is becoming increasingly apparent that various hormones in the hypothalamus-pituitary-thyroid axis may be associated with functional stroke outcome. We have previously shown that white matter hyperintensities (WMH) of presumed vascular origin are strong indicators of functional outcome. It is unclear whether an association exists between WMH and TSH. We therefore sought to determine whether TSH levels, measured in acute ischemic stroke patients, are associated with WMH and functional outcome.

Methods

We analyzed all first ischemic stroke patients who participated in the Berlin ‘Cream & Sugar’ Study (NCT 01378468) and completed a 1-year follow-up assessment from January 2009 to March 2013. Patients were stratified into 3 groups: (1) low TSH (0.1-0.44 μU/ml); (2) normal TSH (0.44-2.5 μU/ml), and (3) high TSH (2.5-20 μU/ml). WMH were assessed using the Fazekas and Wahlund visual rating scales. Functional outcome was assessed using the modified Rankin Scale and was performed via telephone at 1 year by a certified rater.

Results

183 patients were included [median age 66, interquartile range (IQR) 54-75; 33% females; median National Institute of Health Stroke Scale 3, IQR 1-4, range 0-24]. Venous samples were collected a median of 4 days (IQR 3-5) following initial symptom onset between 8 and 9 a.m. following a 10-hour fast. Patients with normal TSH levels (n = 132; 72%) had significantly higher rates of prestroke diabetes than patients with high TSH levels (normal TSH 17%; high TSH 1%; p = 0.03). Additionally, patients with normal TSH levels tended to have higher estimated glomerular filtration rates than patients with high and low TSH concentrations (normal TSH median estimated glomerular filtration rates: 83 ml/min/1.73 m²; high TSH median estimated glomerular filtration rates: 76 ml/min/1.73 m²; low TSH median: 78 ml/min/1.73 m²; p = 0.068). Logistical regression analysis force-adjusted for age (quartiles), NIHSS (quartiles), prestroke diabetes status, and stroke subtype revealed significant associations between WMH and TSH [Wahlund scores: odds ratio 2.547, 95% confidence interval (CI) 1.159-5.598, p = 0.020; Fazekas scores: odds ratio 2.530, 95% CI 1.115-5.741, p = 0.003]. Functional outcome was not significantly associated with TSH levels in univariate or multivariate models.

Conclusion

TSH levels are independently associated with WMH in acute ischemic stroke patients. Based on our findings, we cannot recommend assessing TSH to estimate the 1-year functional outcome following ischemic stroke.

An update on subclinical hypothyroidism and subclinical hyperthyroidism

Subclinical thyroid dysfunction is characterized by normal levels of peripheral thyroid hormone, paired with a TSH level that is either lower than (subclinical hyperthyroidism) or higher than (subclinical hypothyroidism) the normal laboratory reference range. Slight shifts in peripheral hormone levels result in significant serum TSH changes. The exact upper limit of normal TSH and the management of subclinical hypothyroidism are still controversial. For those with TSH between high upper limit of normal and 10 mIU/L, the authors suggest selective use of thyroxine therapy. The authors agree with the general consensus in favor of therapy for those with serum TSH levels above 10 mIU/L. This recommendation is compatible with guidelines of American Thyroid Association and American Association of Clinical Endocrinologists. For subclinical hyperthyroidism persistent serum TSH <0.1 mIU/L should be treated particularly if the etiology is nodular toxic goiter. For serum TSH between 0.1 mIU/L and lower limit of normal, serum TSH co-morbidities such as cardiac risk factors and osteoporosis may favor therapy.

Changes in thyroid hormone receptors after permanent cerebral ischemia in male rats

Thyroid hormones (TH) and receptors (TRs) may play an important role in the pathophysiology of acute cerebral ischemia. In the present study, we sought to determine whether serum triodothyronine (T3)/thyroxine (T4) and brain TRs (TRα1, TRβ1) might change after experimental stroke. Male adult Wistar rats were subjected to permanent middle cerebral artery occlusion (group P) and compared to sham-operated controls (group S). Animals were followed clinically for 14 days until brain collection for Western blot (WB) or neuropathological analysis of TRs in three different brain areas (infarcted tissue, E1; noninfarcted ipsilateral hemisphere, E2; and contralateral hemisphere, E3). Analysis of serum TH levels showed a reduction of T4 in group P (p = 0.002) at days 2 to 14, while half of the animals also displayed "low T3" values (p = 0.012) on day 14. This T4 reduction was inversely correlated to the clinical severity of stroke and the concomitant body weight loss (p < 0.005). WB analysis of TRα1 and TRβ1 protein expression showed heterogenic responses at day 14: total and nuclear TRα1 were similar between the two groups, while total TRβ1 decreased 7.5-fold within E1 (p ≤ 0.001) with a concomitant 1.8-fold increase of nuclear TRβ1 in E2 area (p = 0.03); TRβ1 expression did not differ in E3. Neuropathological analysis revealed that activated macrophages/microglia exclusively expressed nuclear TRα1 within the infarct core. Astrocytes mildly expressed nuclear TRα1 in and around the infarct, along with a prominent TRβ nuclear signal restricted in the astrocytic scar. Neurons around the infarct expressed mainly TRα1 and, to a milder degree, TRβ. Surprisingly enough, we detected for the first time a TRβ expression in the paranodal region of Ranvier nodes, of unknown significance so far. Our data support that cerebral ischemia induces a low TH response, associated with significant and heterogenic changes in brain TR expression. These findings could imply an important role of TH signaling in cerebral ischemia.

Subclinical hypothyroidism and left ventricular mechanics: a three-dimensional speckle tracking study

CONTEXT

Subclinical hypothyroidism (SHT) is associated with left ventricular (LV) remodeling. The LV mechanics has not been previously assessed by two- and three-dimensional (2DE and 3DE) speckle tracking imaging in the SHT patients.

OBJECTIVES

The objective of the study was to investigate LV mechanics by 2DE and 3DE speckle tracking in the SHT patients and evaluate the influence of levothyroxine therapy on LV remodeling.

DESIGN

We conducted a prospective study. All SHT patients received levothyroxine therapy and were followed up for 1 year after the euthyroid state had been achieved.

SETTING

The study was performed at a university hospital.

PATIENTS

We included 54 untreated women with SHT and 40 healthy control women who were of similar age.

MAIN OUTCOME MEASURES

The 2DE strain and strain rates, 3DE volumes, 3DE strain, and thyroid hormones levels were assessed.

RESULTS

The 2DE LV longitudinal and circumferential strain and systolic and early diastolic strain rates were significantly decreased in the SHT patients before therapy in comparison with the controls or the SHT patients after therapy. The 3DE LV cardiac output and ejection fraction were significantly reduced in the SHT patients at baseline compared with the controls or patients after 1 year of treatment. The 3DE LV longitudinal and radial strains were significantly lower in the SHT group before treatment in comparison with the controls or patients after therapy, whereas the 3DE LV circumferential and area strains gradually increased from untreated SHT patients, among the treated SHT patients, to the controls.

CONCLUSION

SHT significantly affects LV deformation assessed by 2DE and 3DE speckle tracking. The improvement of LV mechanics after 1 year of levothyroxine treatment is significant but incomplete.

Subclinical thyroid dysfunction and cardiac function amongst minority ethnic groups in the UK: a cross sectional study

BACKGROUND

Subclinical thyroid disease is associated with abnormal cardiovascular haemodynamics and increased risk of heart failure. The burden of raised/low thyroid stimulating hormone (TSH) levels amongst South Asian (SA) and African-Caribbean (AC) minority groups in the UK is not well defined. Given that these groups are particularly susceptible to CVD, we hypothesised that STD would reflect abnormal cardiac function and heightened cardiovascular risk in these ethnic groups.

METHODS

We examined SA (n=1111, 56% male, mean age 57.6 yrs) and AC (n=763, 44% male, mean age 59.2 yrs) participants from a large heart failure screening study. Euthyroidism is defined as TSH (0.4 - 4.9 mlU/l), subclinical hypothyroidism is defined as a raised TSH with normal serum free thyroxine (FT4) concentrations (9-19 pmol/l). Subclinical hyperthyroidism is defined as a low TSH with both FT4 and free triiodothyronine (FT3) concentrations within range (2.6-5.7 pmol/l).

RESULTS

Across ethnic groups, prevalence of subclinical hypothyroidism was 2.9% (95% CI 2.1-3.7), and of hyperthyroidism was 2.0% (1.4-2.7). Hyperthyroidism was more common amongst SA compared to AC (2.8% vs. 0.9%, P=0.017), while rates of subclinical hypothyroidism were similar. On multivariate analysis of variations in subclinical thyroid function, ethnicity was not independently significant.

CONCLUSION

The prevalence of subclinical thyroid disorders amongst SA and AC minority groups in Britain reflects levels reported in other populations. The clinical cardiovascular significance of subclinical thyroid disease is unclear, and it does not appear to be ethnically specific.