The changes in the endothelial function and haemostatic and inflammatory parameters in subclinical and overt hyperthyroidism

Association of thyroid dysfunction in individuals ≥ 65 years of age with subclinical cardiac abnormalities

CONTEXT

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

OBJECTIVE

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

DESIGN

Cross-sectional analysis.

SETTING

The Cardiovascular Health Study, a community-based cohort of older individuals recruited from four urban areas in the United States.

PATIENTS

Of 3163 participants studied, 2477 were euthyroid, 465 had subclinical hypothyroidism (SCH), 47 overt hypothyroidism (OH), 45 endogenous (endo) subclinical hyperthyroidism (endo-SCT), and 129 had exogenous (exo) SCT due to thyroid hormone supplementation.

INTERVENTIONS

Clinical evaluation, blood sampling and biomarker measurement, 2-dimensional and speckle-tracking echocardiography.

MAIN OUTCOME MEASURE(S)

Left heart myocardial deformation, circulating biomarkers of diastolic overload (NT-proBNP), fibrosis (sST2, gal-3), and cardiomyocyte injury (hs-cTnT).

RESULTS

SCH was associated with higher NT-proBNP (beta = 0.17, p = 0.004), whereas OH was associated with higher hs-cTnT (beta = 0.29, p = 0.005). There were also suggestive associations of SCH with higher sST2, as well as endo-SCT with higher gal-3 and lower (worse) left atrial reservoir strain. Left ventricular longitudinal strain and end-diastolic strain rate did not differ significantly from euthyroid participants in SCH, OH, or exo-SCT.

CONCLUSIONS

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

Four-dimensional speckle tracking echocardiography and fragmented QRS in detection of early left ventricular systolic dysfunction in patients with subclinical hyperthyroidism

BACKGROUND

Thyroid disorders are associated with many cardiovascular risk factors. The importance of thyroid hormones in the pathophysiology of heart failure is underlined by the European guidelines of the European Society of Cardiology. However, the role of subclinical hyperthyroidism (SCH) in subclinical left ventricular (LV) systolic dysfunction is not entirely clear.

METHODS

This cross-sectional study included 56 SCH patients and 40 healthy volunteers. The 56 SCH group was divided into two subgroups depending on the presence of fragmented QRS (fQRS). In both groups, left ventricular global area strain (LV-GAS), global radial strain (GRS), global longitudinal strain (GLS), and global circumferential strain (GCS) were obtained with four-dimensional (4D) echocardiography.

RESULTS

GAS, GRS, GLS, and GCS values were significantly different in SCH patients and in healthy volunteers. GLS and GAS values were lower in the fQRS+ than in the fQRS- group (-17.06 ± 1.00 vs. -19.08 ± 1.71, p < .001, and -26.61 ± 2.38 vs. -30.61 ± 2.57, p < .001, respectively). ProBNP was positively correlated with LV-GLS (r = 0.278, p = .006) and LV-GAS (r = 0.357, p < .001). Multiple linear regression analysis showed that fQRS was an independent predictor of LV-GAS.

CONCLUSIONS

4D strain echocardiography may be helpful for the prediction of early cardiac dysfunction in patients with SCH. The presence of fQRS may be an indicator of subclinical LV dysfunction in SCH.

Changes in biochemical, immunological and inflammatory parameters in hyper and hypothyroidism: A systematic review

This review presents an assessment of alterations in various biomarkers in hyper and hypothyroidism. In hyperthyroidism, the level of thyroid hormone increases while it decreases in the case of hypothyroidism. The thyroid gland has been implicated in a broad spectrum of carbohydrate metabolism, imbalance of lipid profile, and mineral metabolism. Autoimmunity and inflammatory reactions in the thyroid gland might lead to the conditions like hyper and hypothyroidism. Lipid profile dysfunction is common in hypothyroidism patients while a higher level of liver enzymes is associated with hyperthyroidism. Glucose level has been observed to increase in both conditions. Hypothyroid patients are more prone to autoimmune conditions in comparison to hyperthyroid patients. According to the type of thyroid disorder, the concentrations of various biochemical, immunological and inflammatory markers alter. The literature reviewed in this article establishes considerable changes in the above parameters among thyroid patients which might help further in the early diagnosis and management of thyroid dysfunctions.

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.

Evaluation of hemostasis in hyperthyroid cats

Background

Hyperthyroid cats might have a predisposition to arterial thrombus formation. The mechanism for thrombogenesis currently is unknown but could be associated with systemic hypercoagulability as seen in hyperthyroid humans.

Objective

Our purpose was to evaluate markers of hemostasis in hyperthyroid cats compared to healthy cats, and in hyperthyroid cats before and after radioactive iodine treatment (RIT).

Animals

Twenty‐five cats with hyperthyroidism and 13 healthy euthyroid cats >8 years of age.

Methods

Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration, antithrombin (AT), D‐dimers, thrombin‐antithrombin complexes (TAT), von Willebrand Factor antigen (vWF : Ag), and activity of factors VIII and IX were measured. An echocardiogram was performed in all cats. Hemostatic markers and echocardiogram were evaluated again 6 to 9 months after successful RIT in 7 cats.

Results

Hyperthyroid cats had higher fibrinogen concentration (P < .0001), AT activity (P < .0001), and vWF : Ag concentration (P = .01) than healthy control cats with all results decreasing significantly post‐RIT. Hyperthyroid cats were not more likely to be in a hypercoaguable state than euthyroid cats (P = .08). Serum T4 concentration was not a predictor of a hypercoagulable state (P = .53).

Conclusions and Clinical Importance

Hyperthyroid cats have evidence of altered hemostasis that does not appear to be solely attributable to cardiac abnormalities, but no evidence of a hypercoagulable state. Findings suggest altered hemostasis resolves after RIT. Hyperthyroid cats could have endothelial dysfunction as indicated by increased vWF : Ag which could potentiate thrombogenesis.

Evaluation of Thyroid Function in Patients Hospitalized for Acute Heart Failure

BACKGROUND

Thyroid hormones (TH) are crucial for cardiovascular homeostasis. Recent evidence suggests that acute cardiovascular conditions, particularly acute heart failure (AHF), significantly impair the thyroid axis. Our aim was to evaluate the association of thyroid function with cardiovascular parameters and short- and long-term clinical outcomes in AHF patients.

METHODS

We performed a single-centre retrospective cohort study including patients hospitalized for AHF between January 2012 and December 2017. We used linear, logistic, and Cox proportional hazard regression models to analyse the association of thyroid-stimulating hormone (TSH) and free thyroxine (FT4) with inpatient cardiovascular parameters, in-hospital mortality, short-term adverse clinical outcomes, and long-term mortality. Two models were used: (1) unadjusted, and (2) adjusted for age and sex.

RESULTS

Of the 235 patients included, 59% were female, and the mean age was 77.5 (SD 10.4) years. In the adjusted model, diastolic blood pressure was positively associated with TSH [β = 2.68 (0.27 to 5.09); p = 0.030]; left ventricle ejection fraction (LVEF) was negatively associated with FT4 [β = -24.85 (-47.87 to -1.82); p = 0.035]; and a nonsignificant trend for a positive association was found between 30-day all-cause mortality and FT4 [OR = 3.40 (0.90 to 12.83); p = 0.071]. Among euthyroid participants, higher FT4 levels were significantly associated with a higher odds of 30-day all-cause death [OR = 4.40 (1.06 to 18.16); p = 0.041]. Neither TSH nor FT4 levels were relevant predictors of long-term mortality in the adjusted model.

CONCLUSIONS

Thyroid function in AHF patients is associated with blood pressure and LVEF during hospitalization. FT4 might be useful as a biomarker of short-term adverse outcomes in these patients.

Platelet function in cats with hyperthyroidism

OBJECTIVES

Cats with hyperthyroidism have been reported to develop thromboembolism, with and without echocardiographic abnormalities consistent with hyperthyroidism. The objective of this study was to compare platelet function in cats with hyperthyroidism with euthyroid age-matched cats. We hypothesized that cats with hyperthyroidism have shortened collagen and adenosine diphosphate (C-ADP) closure times as measured with the platelet function analyzer (PFA-100) in comparison with healthy, age-matched controls.

METHODS

Sixteen hyperthyroid and nine euthyroid healthy cats >7 years of age were recruited from the hospital population. Platelet function, measured using the C-ADP closure times by the PFA-100, and platelet count were measured in healthy euthyroid cats and cats with hyperthyroidism.

RESULTS

Mean ± SD closure times were not significantly different between control (66.3 ± 9.6 s) and hyperthyroid cats (65.9 ± 11.5 s; P = 0.75). The mean ± SD closure times of hyperthyroid cats that either were untreated or received methimazole for ⩽3 weeks (n = 6; mean 68.5 ± 15.4 s) was not different than that of cats treated for >3 weeks (n = 10; mean 64.3 ± 8.9 s; P = 0.57). The mean automated platelet count was higher in the hyperthyroid group than in the control group (P = 0.023).

CONCLUSIONS AND RELEVANCE

Platelet function, as measured by closure time under high shear conditions using C-ADP as an agonist, was not affected by hyperthyroidism in this group of cats. Further research is needed to determine if a hypercoagulable state exists in hyperthyroid cats and the potential roles platelets and von Willebrand factor may have.

Subclinical Thyroid Dysfunction and the Risk of Cardiovascular Disease

The prevalence of subclinical hypothyroidism (SH) is 3-10%. The prevalence of subclinical hyperthyroidism (SHr) is 0.7-9.7%. Thyroid hormones affect cardiac electrophysiology, contractility, and vasculature. SH is associated with an increased risk of coronary heart disease (CHD), especially in subjects under 65. SHr seems to be associated with a slightly increased risk of CHD and an increase in CHD-related mortality. Both SH and SHr carry an increased risk of developing heart failure (HF), especially in those under 65. Both SH and SHr are associated with worse prognoses in patients with existing HF. SH is probably not associated with atrial fibrillation (AF). SHr, low normal thyroid-stimulating hormone (TSH) and high normal free thyroxine (FT4) are all associated with the increased risk of AF. An association between endothelial dysfunction and SH seems to exist. Data regarding the influence of SHr on the peripheral vascular system are conflicting. SH is a risk factor for stroke in subjects under 65. SHr does not increase the risk of stroke. Both SH and SHr have an unfavourable effect on cardiovascular disease (CVD) and all-cause mortality. There is a U-shaped curve of mortality in relation to TSH concentrations. A major factor that modifies the relation between subclinical thyroid disease (SCTD) and mortality is age. SH increases blood pressure (BP). SHr has no significant effect on BP. Lipids are increased in patients with SH. In SHr, high-density lipoprotein cholesterol and lipoprotein( a) are increased. SCTD should be treated when TSH is over 10 mU/l or under 0.1 mU/l. Treatment indications are less clear when TSH is between normal limits and 0.1 or 10 mU/L. The current state of knowledge supports the understanding of SCTD's role as a risk factor for CVD development. Age is a significant confounding factor, probably due to age-associated changes in the TSH reference levels.

Hyperthyroidism and vascular cell adhesion molecule-1 are associated with a low ankle-brachial index

We aimed to assess the ankle-brachial index (ABI) in patients with Graves' disease. In the cross-sectional assessments, 81 patients with drug-naïve Graves' disease and 235 with euthyroidism were enrolled. ABI and vascular cell adhesion molecule-1 (VCAM-1) levels were assessed. In the prospective follow-up, 32 patients with Graves' disease were assessed again after antithyroid drugs for at least 4 weeks, and 32 age- and sex-matched controls with euthyroidism were also followed up. Patients with Graves' disease had a higher VCAM-1 level (1309 ± 292 vs. 1009 ± 168 ng/mL, P < 0.001) and a lower ABI (0.98 ± 0.11 vs. 1.06 ± 0.10, P < 0.001) than those with euthyroidism. ABI was significantly lower in patients with hyperthyroidism and a high VCAM-1 level than in those with euthyroidism and a low VCAM-1 level (regression coefficient: - 0.050, 95% confidence interval [CI] between - 0.080 and - 0.019; P = 0.001). After treatment with antithyroid drugs, the change in free thyroxine (T4) level was inversely associated with the percentage change in ABI (regression coefficient: - 0.003, 95% CI between - 0.005 and - 0.001, P = 0.001). A synergistic effect of VCAM-1 and free T4 on ABI reduction was observed. After a longitudinal follow-up, an increase in ABI was significantly correlated with a decrease in the free T4 level.

Plasma-Based Proteomics Profiling of Patients with Hyperthyroidism after Antithyroid Treatment

Thyroid hormones critically modulate body homeostasis and haemostasis by regulating energy and metabolism. Previous studies have focused on individual pathways or proteins that are affected by increases in thyroid hormone levels, while an overall plasma proteomic signature of this increased level is lacking. Herein, an integrated untargeted proteomic approach with network analysis was used to identify changes in circulating proteins in the plasma proteome between hyperthyroid and euthyroid states. Plasma from 10 age-matched subjects at baseline (hyperthyroid) and post treatment with carbimazole (euthyroid) was compared by difference gel electrophoresis (DIGE) and matrix-assisted laser desorption/ionization time of flight (MALDI TOF) mass spectrometry (MS). A total of 20 proteins were identified with significant difference in abundance (analysis of variance (ANOVA) test, p ≤ 0.05; fold-change ≥ 1.5) between the two states (12 increased and 8 decreased in abundance in the hyperthyroid state). Twelve protein spots corresponding to ten unique proteins were significantly more abundant in the hyperthyroid state compared with the euthyroid state. These increased proteins were haptoglobin (HP), hemopexin (HPX), clusterin (CLU), apolipoprotein L1 (APOL1), alpha-1-B glycoprotein (A1BG), fibrinogen gamma chain (FGG), Ig alpha-1 chain C region (IGHA1), complement C6 (C6), leucine rich alpha 2 glycoprotein (LRG1), and carboxypeptidase N catalytic chain (CPN1). Eight protein spots corresponding to six unique proteins were significantly decreased in abundance in the hyperthyroid samples compared with euthyroid samples. These decreased proteins were apolipoprotein A1 (APOA1), inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4), plasminogen (PLG), alpha-1 antitrypsin (SERPINA1), fibrinogen beta chain (FGB), and complement C1r subcomponent (C1R). The differentially abundant proteins were investigated by ingenuity pathway analysis (IPA). The network pathway identified related to infectious disease, inflammatory disease, organismal injury and abnormalities, and the connectivity map focused around two central nodes, namely the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and p38 mitogen-activated protein kinase (MAPK) pathways. The plasma proteome of patients with hyperthyroidism revealed differences in the abundance of proteins involved in acute phase response signaling, and development of a hypercoagulable and hypofibrinolytic state. Our findings enhance our existing knowledge of the altered proteins and associated biochemical pathways in hyperthyroidism.

Changes in left ventricular function and contractile homogeneity in young adults with newly diagnosed hyperthyroidism due to Graves' disease

PURPOSE

The aim of this study was to investigate myocardial dysfunction and mechanical abnormalities in young patients with Graves' disease before therapy, using two-dimensional speckle tracking echocardiography.

METHODS

We performed a comprehensive transthoracic echocardiographic examination, including segmental and global radial strain, and time-to-peak radial strain, in 47 young patients with hyperthyroidism and 34 healthy adults. The time-to-peak radial strain was corrected by RR interval. The variables derived from radial myocardial deformation by the six-basal, six-mid, and six-apical segmental model were compared to investigate the difference of the myocardial function between the two groups.

RESULTS

Early diastolic mitral inflow velocity, E/A ratio, early diastolic mitral annular velocity, and e'/a' ratio were lower in patients with Graves' disease than in controls. The left ventricular end-diastolic volume, left ventricular end-systolic volume, stroke volume, cardiac output, heart rate, late diastolic mitral inflow velocity, and late diastolic mitral annular velocity were slightly higher in patients than in controls. Radial strain, global radial strain, and corrected time-to-peak radial strain were lower in the patient group.

CONCLUSIONS

The decreased radial strain, global radial strain, and corrected time-to-peak radial strain in young patients with newly diagnosed hyperthyroidism due to Graves' disease could serve as an early sign of subclinical cardiac involvement.

Left Ventricular Assist Device Thrombosis-Amiodarone-Induced Hyperthyroidism: Causal Link?

Ventricular arrhythmias occurs in 20-50% of patients supported with left ventricular assist devices (LVAD). Ventricular arrhythmias are well tolerated with LVAD support but long-term consequences include worsening right ventricular function. Management of ventricular arrhythmias in LVAD patients includes use of antiarrhythmic agents or ablation. Amiodarone has been used a first-line agent to treat ventricular arrhythmias post-LVAD implantation. Chronic treatment with amiodarone for arrhythmias can result in hyperthyroidism and hypothyroidism in 5-10% of patients. Hyperthyroidism is known to cause endothelial dysfunction, alterations in coagulation, and fibrinolytic pathways favoring hypercoagulable state. We describe two cases of left ventricular assist device (LVAD) thrombosis potentiated by amiodarone-induced hyperthyroidism (AIT) and discuss pathophysiological mechanisms for hypercoagulable state induced by hyperthyroidism.

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.

Role of Adipokines in the Association between Thyroid Hormone and Components of the Metabolic Syndrome

Metabolic syndrome (MS) increases cardiovascular risk. The role of thyroid hormone on components of MS is unclear. We analyzed a sample of 4733 euthyroid subjects from SardiNIA study. In female thyrotropin (TSH) was significantly and positively associated with triglycerides (Standardized regression coefficients (β) = 0.081, p < 0.001). Free thyroxine (FT4) was positively associated with HDL (β = 0.056, p < 0.01), systolic blood pressure (SBP) (β = 0.059, p < 0.001), diastolic blood pressure (DBP) (β = 0.044, p < 0.01), and fasting glucose (β = 0.046, p < 0.01). Conversely, FT4 showed a negative association with waist circumference (β = −0.052, p < 0.001). In TSH was positively associated with triglycerides (β = 0.111, p < 0.001) and FT4 showed a positive association with DBP (β = 0.51, p < 0.01). The addition of leptin and adiponectin to the regression models did not substantially change the impact of thyroid hormones on components of MS. Our data suggest that, even within the euthyroid range, excess of truncal adipose tissue is associated with variations in FT4. Leptin and adiponectin exert an additive effect rather than a causal effect. Additional studies should be performed to determine the clinical significance of this finding.

Hypertension in Thyroid Disorders

Arterial hypertension represents a major global health concern; more than one fourth of the population is affected by high blood pressure. Albeit the underlying cause of the disease remains unclear in the vast majority of the cases, ~10% are of secondary origin. Endocrine disorders are common illnesses and some of them may lead to elevated blood pressure, among which thyroid diseases are of high prevalence and often overlooked, especially in mild cases. Overt and subclinical hyper- and hypothyroidism can both lead to (mostly mild) hypertension; however, the underlying mechanisms are only partially understood. The results of clinical studies are often controversial. During the past decades, some genetic mutations in the hypothalamus-pituitary-thyroid axis with cardiovascular consequences were revealed. Atherosclerotic changes resulting from lipid abnormalities due to thyroid dysfunction also affect the vasculature and can cause elevated blood pressure. The review gives a synopsis of our knowledge how thyroid hormone metabolism and functional thyroid diseases affect the cardiovascular system, their negative impact and causative role in the development of hypertension.

Effects of thyroxine on adhesion molecules and proinflammatory cytokines secretion on human umbilical vein endothelial cells

Thyroid dysfunction is associated with elevated cardiovascular risk factors and atherosclerosis. It could be suggested that, hyperthyroidism is related to a higher prevalence of arterial abnormalities. Therefore, evaluating the endothelial dysfunction (ED) related biomarkers seem to be an important issue. It is not clear whether endothelial cells are biologically responsive to thyroid hormones (THs) or how THs induces the production of endothelial cells (EC)-derived proinflammatory mediators. Hence, in this study the effects of thyroxine (T₄) on ED and inflammatory related mediators were evaluated. Human umbilical vein endothelial cells was used as endothelial cell model which was treated with concentrations of 50, 100, 200 nmol/L of T₄ in various exposure times. In the following, gene and protein expression levels of EC-related markers including intercellular adhesion molecule-1 (ICAM-1), vascular endothelial growth factor (VEGF), and E-selectin were determined using real time polymerase chain reaction (RT-PCR) and western blotting methods. Also, interleukin-6 (IL-6) and tumor necrosis factor (TNF-α) protein levels as proinflammatory cytokines were determined by enzyme linked immunosorbent assay (ELISA) method. Gene and protein expression analysis revealed that T₄ treatments up regulated the levels of VEGF, ICAM-1, and E-selectin as ED markers. In addition, T₄-treated cells had higher significant levels of IL-6 and TNF-α versus untreated cells in different incubation times. This study proposed the atherosclerotic effects of thyroid hormone. Based on our findings, T4 had strong effects on the gene and protein expression levels of pro-inflammatory, angiogenesis, and ED major mediators associated with atherosclerosis development.

Weathering the storm: A case of thyroid storm refractory to conventional treatment benefiting from therapeutic plasma exchange

Thyroid storm is a severe manifestation of thyrotoxicosis characterized by systemic organ dysfunction secondary to a hypermetabolic state. Although antithyroid drugs, steroids, beta-blockers, antipyretics, and cholestyramine are the standard of care, some patients inadequately respond to these conventional therapies. Therapeutic plasma exchange has been previously utilized as a treatment modality in patients with a poor response to routine therapies or with contraindications to them. Herein, we report our experience with the management of a case of thyroid storm refractory to conventional treatment but responsive to therapeutic plasma exchange.

Relationship between serum thyrotropin and urine albumin excretion in euthyroid subjects with diabetes

BACKGROUND

Microalbuminuria represents vascular and endothelial dysfunction. Thyroid hormones can influence urine albumin excretion as it exerts crucial effects on the kidney and on the vascular system. This study explores the relationship between serum thyrotropin and urine albumin excretion in euthyroid patients with diabetes.

METHODS

A total of 433 patients with type 1 or 2 diabetes were included in this retrospective cross-sectional study. Data included anthropometric measurements and biochemical parameters from diabetes clinic. Males with urine albumin creatinine ratio >2.5 and female's >3.5 mg/mmoL were considered to have microalbuminuria.

RESULTS

34.9% of the patients had microalbuminuria. Prevalence of microalbuminuria increased according to TSH quartiles (26.9, 34.6, 38.5 and 44.9%, P for trend = 0.02). In a fully adjusted logistic regression model, higher TSH concentrations were associated with high prevalence of microalbuminuria (adjusted odds ratio 2.06 [95% CI: 1.14-3.72]; P = 0.02), while comparing the highest with the lowest quartile of TSH. Multiple linear regression analysis showed an independent association between serum TSH and urine albumin creatinine ratio (β = 0.007, t = 2.03 and P = 0.04). The risk of having microalbuminuria was higher with rise in TSH concentration in patients with younger age (<65 years), raised body mass index (≥25 kg/m²), hypertension, type 2 diabetes and hyperlipidaemia and age was the most important determinant ( P for interaction = 0.02).

CONCLUSION

Serum TSH even in the euthyroid range was positively associated with microalbuminuria in euthyroid patients with diabetes independent of traditional risk factors. This relationship was strongest in patients with components of the metabolic syndrome.

New Interfaces of Thyroid Hormone Actions With Blood Coagulation and Thrombosis

Substantial clinical evidence indicates hyperthyroidism enhances coagulation and increases the risk of thrombosis. In vitro and clinical evidence implicate multiple mechanisms for this risk. Genomic actions of thyroid hormone as 3,5,3′-triiodo-L-thyronine (T₃) via a nuclear thyroid hormone receptor have been implicated, but recent evidence shows that nongenomic mechanisms initiated at the receptor for L-thyroxine (T₄) on platelet integrin αvβ3 are prothrombotic. The T₄-initiated mechanisms involve platelet activation and, in addition, cellular production of cytokines and chemokines such as CX3CL1 with procoagulatory activities. These procoagulant actions of T₄ are particulary of note because within cells T4 is not seen to be functional, but to be only a prohormone for T₃. Finally, it is also possible that thyroid hormone stimulates platelet-endothelial cell interaction involved in local thrombus generation. In this brief review, we survey mechanisms by which thyroid hormone is involved in coagulation and platelet functions. It is suggested that the threshold should be lowered for considering the possibility that clinically significant clotting may complicate hyperthyroidism. The value of routine measurement of partial thromboplastin time or circulating D-dimer in patients with hyperthyroid or in patients treated with thyrotropin-suppressing dosage of T₄ requires clinical testing.

Association between low thyroid-stimulating hormone, posterior cortical atrophy and nitro-oxidative stress in elderly patients with cognitive dysfunction

INTRODUCTION

Cortical atrophy is known to be a valuable sign of cognitive decline. The purpose of this study was to assess the association between low thyroid-stimulating hormone (TSH), posterior cortical atrophy (Koedam score - KS) and nitro-oxidative stress in elderly patients.

MATERIAL AND METHODS

A study (SG) and a control group (CG), each subdivided by gender, were investigated. Subjects older than 59 years with low serum TSH level and with mild cognitive impairment were included in the SG. The CG was formed by subjects free of significant cortical atrophy and free or thyroid dysfunction. Demographic and clinical characteristics of the patients (Mini Mental State Examination, MMSE), Koedam score on cranial magnetic resonance imaging, and blood parameters (TSH, FT4, and nitric oxide - NOx) were assessed.

RESULTS

Subjects in the study group had fewer years of education above the 8th grade compared with the control group (p < 0.0001). A significantly higher percentage of subjects in the study group had a Koedam score of 2 or 3 compared with controls, who had in the majority of cases a Koedam score of zero (p < 0.02). Significantly higher NOx levels were observed when study groups of both genders were compared with corresponding controls (p < 0.001). No significant differences were observed with regard to FT4 (p > 0.70). Nitric oxide was found to be significantly associated with TSH (p < 0.03) and KS (p < 0.002) when the whole study group was considered as well as when just the non-smoker study group was investigated.

CONCLUSIONS

Our study revealed an association between subclinical thyroid hypofunction, nitro-oxidative stress, and posterior cortical atrophy as an early stage of global atrophy.

Investigation of the association between serum protein concentrations and concurrent chronic kidney disease in hyperthyroid cats

Our objective was to identify if changes in serum protein concentrations occur in hyperthyroidism and to assess their association with the development of azotaemia following treatment. Initially non-azotaemic hyperthyroid cats and healthy older cats were included. Serum concentrations of protein fractions were determined by agarose gel electrophoresis and compared between; hyperthyroid and control cats, initially non-azotaemic hyperthyroid cats which developed azotaemia in a 4month follow up period (masked-azotaemic) and those which remained non-azotaemic, and hyperthyroid cats before and at the time of restoration of euthyroidism. Data are presented as median [25th, 75th percentiles]. Hyperthyroid cats (n=56) had higher serum α₂ globulin concentrations (12.5 [10.9, 13.1] g/L vs. 9.8 [3.0, 11.4] g/L; P<0.001) and lower serum γ globulin concentrations (11.4 [9.1, 13.3] g/L vs. 14.0 [12.4, 16.8] g/L; P=0.001) than control cats (n=26). Following treatment, serum total globulin concentration increased (from 38.6 [35.4, 42.8] g/L to 42.3 [39.0, 45.7] g/L; P<0.001), serum α₂ globulin concentration decreased (from 12.5 [10.9, 13.9] g/L to 11.5 [10.1, 12.6] g/L; P<0.001) and serum γ globulin concentration increased (from 11.4 [9.0, 13.3] g/L to 14.0 [12.4, 16.8] g/L; P<0.001). Serum concentrations of total globulin or globulin fractions were not significantly different between masked-azotaemic and non azotaemic groups. In conclusion, hyperthyroidism is associated with altered serum concentrations of the α₂ and γ globulin fractions, however these changes were not associated with the development of azotaemic chronic kidney disease following treatment.

Hemostasis in Overt and Subclinical Hyperthyroidism

CONTEXT

There are contradictory results on the effect of hyperthyroidism on hemostasis. Inadequate population-based studies limited their clinical implications, mainly on the risk of venous thromboembolism (VTE). The present review focuses on hemostatic changes in overt and subclinical hyperthyroidism.

METHODS

A systematic literature search was conducted employing MEDLINE database. The following words were used for the search: Hyperthyroidism; thyrotoxicosis; Graves disease; goiter, nodular; hemostasis; blood coagulation factors; blood coagulation disorders; venous thromboembolism; bleeding; fibrinolysis. The articles that were related to hyperthyroidism and hemostasis are used in this manuscript.

RESULTS

Hyperthyroidism, either overt or subclinical, renders a hypercoagulable state, although there are several studies with contradictory findings in the literature. Hypercoagulability may be caused by an increase in the level of various coagulation factors such as factor (F) VIII, FX, FIX, von Willebrand F (vWF), and fibrinogen, while hypofibrinolysis by changes in coagulation parameters such as a decrease in plasmin and plasmin activator or an increase in α2-antiplasmin, plasminogen activator inhibitor-1 and thrombin activatable fibrinolysis inhibitor.

CONCLUSIONS

Although many reports are in favor of a hypercoagulable state in overt hyperthyroidism but this finding at the biochemical level and its clinical implication, on the occurrence of VTE, has yet to be confirmed.

Relationship between Subclinical Thyroid Dysfunction and the Risk of Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

BACKGROUND

Evidence on the association between subclinical thyroid dysfunction and the risk of cardiovascular outcomes are conflicting.

METHODS AND RESULTS

PubMed, EMbase, Web of Science, Cochrane Library, and China Biology Medicine (CBM) databases were searched from inception to July 10, 2016. A total of 16 studies were included for meta-analysis. We found that subclinical hypothyroidism was not correlated with coronary heart disease (CHD) (RR = 1.17; 95% CI, 0.91-1.52), total mortality (RR = 1.02; 95% CI, 0.93-1.13), cardiovascular mortality (RR = 1.06; 95% CI, 0.77-1.45), heart failure (RR = 1.17; 95% CI, 0.87-1.57), and atrial fibrillation (RR = 1.05; 95% CI, 0.91-1.21), except CHD mortality (RR = 1.37; 95% CI, 1.03-1.84). Subgroup analysis indicated a higher estimation risk in CHD (RR = 1.54; 95% CI, 1.00-2.39), cardiovascular mortality (RR = 2.14; 95% CI, 1.43-3.22), and CHD mortality (RR = 1.54; 95% CI, 1.11-2.15) among participants < 65 years. Furthermore, subclinical hyperthyroidism was found to be associated with CHD (RR = 1.20; 95% CI, 1.02-1.42), total mortality (RR = 1.27; 95% CI, 1.07-1.51), and CHD mortality (RR = 1.45; 95% CI, 1.12-1.86).

CONCLUSIONS

Subclinical hypothyroidism is likely associated with an increased risk of CHD mortality, and subclinical hyperthyroidism is likely associated with increased risk of CHD, CHD mortality, and total mortality.

Thyrotropin and CD40L Stimulate Interleukin-12 Expression in Fibrocytes: Implications for Pathogenesis of Thyroid-Associated Ophthalmopathy

BACKGROUND

Increased numbers of bone marrow-derived progenitor cells, known as fibrocytes, populate the peripheral circulation, orbit, and thyroid of patients with Graves' disease (GD). These cells have been implicated in the development of thyroid-associated ophthalmopathy. They can differentiate into myofibroblasts or adipocytes, produce inflammatory cytokines, and remodel tissue. This study sought to determine whether thyrotropin (TSH) and CD40 ligand (CD40L), implicated in the pathogenesis of GD, induce interleukin-12 (IL-12) in human fibrocytes.

MATERIALS AND METHODS

IL-12 protein concentrations and mRNA levels were measured by Luminex and real-time polymerase chain reaction, respectively. Flow cytometry assessed intracellular IL-12 concentrations. Vector containing IL-12p40 promoter was transfected into cultured fibrocytes, and promoter activity was monitored using luciferase assay.

RESULTS

TSH and CD40L stimulated intracellular IL-12 protein accumulation in peripheral blood fibrocytes. Inhibiting Akt and nuclear factor-κB (NF-κB) activity diminished IL-12 expression in fibrocytes, while TSH did not induce promoter activity. TSH-mediated IL-12 production required de novo synthesized proteins and augmented IL-12 mRNA stability. IL-12 production mediated by CD40L required tumor necrosis factor receptor-associated factor 6.

CONCLUSION

TSH and CD40L induce IL-12 expression in fibrocytes, and Akt and NF-κB mediate this activity. Given the importance of IL-12 in immune function, its production by fibrocytes may promote an inflammatory immune response and tissue remodeling in thyroid-associated ophthalmopathy.

Association between thyroid dysfunction and venous thromboembolism in the elderly: a prospective cohort study

BACKGROUND

Venous thromboembolism (VTE) and subclinical thyroid dysfunction (SCTD) are both common in elderly patients. SCTD has been related to a hypercoagulable state and an increased thromboembolic risk. However, prospective data on the relationship between SCTD and VTE are lacking.

OBJECTIVES

To investigate the relationship between SCTD and recurrent VTE (rVTE), all-cause mortality, and thrombophilic biomarkers. Patients Elderly patients with VTE were studied.

METHODS

In a prospective multicenter cohort, thyroid hormones and thrombophilic biomarkers were measured 1 year after acute VTE, as both may be influenced by acute thrombosis. We defined subclinical hypothyroidism (SHypo) as elevated thyroid-stimulating hormone (TSH) levels (4.50-19.99 mIU L(-1) ), and subclinical hyperthyroidism (SHyper) as TSH levels of < 0.45 mIU L(-1) , both with normal free thyroxine levels. Outcomes were incidence of rVTE and overall mortality during follow-up starting after the 1-year blood sampling.

RESULTS

Of 561 participants (58% with anticoagulation), 6% had SHypo and 5% had SHyper. After 20.8 months of mean follow-up, 9% developed rVTE and 10% died. The rVTE incidence rate was 7.2 (95% confidence interval [CI] 2.7-19.2) per 100 patient-years in SHypo participants, 0.0 (95% CI 0.0-7.6) in SHyper participants, and 5.9 (95% CI 4.4-7.8) in euthyroid participants. In multivariate analyses, the sub-hazard ratio for rVTE was 0.00 (95% CI 0.00-0.58) in SHyper participants and 1.50 (95% CI 0.52-4.34) in SHypo participants as compared with euthyroid participants, without increased levels of thrombophilic biomarkers. SHyper (hazard ratio [HR] 0.80, 95% CI 0.23-2.81) and SHypo (HR 0.99, 95% CI 0.30-3.29) were not associated with mortality.

CONCLUSION

In elderly patients, SHyper may be associated with lower rVTE risks. SHypo showed a non-statistically significant pattern of an association with rVTE, without increased mortality or differences in thrombophilic biomarkers.

Aortic stiffness and left ventricular function in patients with differentiated thyroid cancer

OBJECTIVE

The aim of this study was to investigate aortic stiffness and left ventricular (LV) systolic and diastolic function in patients with differentiated thyroid cancer (DTC) on thyroxine (L-T4) therapy and after L-T4 withdrawal to assess the cardiovascular impact of long-term subclinical hyperthyroidism and short-term overt hypothyroidism.

METHODS

Twenty-four patients who had had total thyroidectomy and radioiodine ablation for differentiated thyroid cancer were studied on two occasions: on TSH suppressive L-T4 therapy (sTSH 0.24 ± 0.11 mU/L), and 4 weeks after L-T4 withdrawal (sTSH 89.82 ± 29.36 mU/L). Echocardiography was performed and thyroid function, serum thyroglobulin, lipid parameters, homocystine, C-reactive protein, fibrinogen and von Willebrand factor activity (vWF) were measured. Twenty-two healthy volunteers matched for age and sex served as euthyroid controls.

RESULTS

Aortic stiffness was increased both in hypothyroidism (6.04 ± 2.88 cm(2)/dyn/10(3), p < 0.05) and subclinical hyperthyroidism (9.27 ± 4.81 cm(2)/dyn/10(3), p < 0.05) vs. controls (3.92 ± 1.84 cm(2)/dyn/10(3)). Subclinical hyperthyroidism had a more marked effect (p < 0.05). LV dimensions and ejection fractions were similar before and after L-T4 withdrawal. The E'/A' was higher in euthyroid controls (1.34 ± 1.02) as compared to both subclinical hyperthyroidism (1.0 ± 0.14, p < 0.05) and overt hypothyroidism (1.13 ± 0.98, p < 0.05). Change of aortic stiffness correlated with change of free-thyroxine (fT4), vWF and fibrinogen levels in a positive manner.

CONCLUSION

Long-term thyrotropin-suppression therapy has continuous adverse effects on the arterial wall. The degree of TSH suppression in patients with DTC should be kept at the possible minimum, based on individually determined potential benefits and risks of treatment, especially in patients with cardiovascular co-morbidities.