New Interfaces of Thyroid Hormone Actions With Blood Coagulation and Thrombosis

Sex-Specific Associations between Thyroid Status, Inflammation and Hemostasis Biomarkers in Patients with Subacute Thyroiditis

Background: Subacute thyroiditis (SAT) is characterized by profound inflammation and fluctuations in thyroid hormones which may affect the hemostasis balance. This study investigates sex-specific associations between thyroid status, inflammation and hemostasis biomarkers in SAT. Methods: We included 52 patients (40 women and 12 men) treated with non-steroidal anti-inflammatory drugs (NSAID) or methylprednisolone (MPS). Free thyroxine (fT4), thyroid stimulating hormone, C-reactive protein, complete blood count and routine hemostasis parameters were assessed. Results: Both men and women were in hyperthyroid state and had comparable levels of inflammatory biomarkers. A shortened activated partial thromboplastin time (aPTT) was observed in 16.7% of the men and 10% of the women (p = 0.562), and a shortened prothrombin time (PT) was observed in 33% of the men and 12.5% of the women (p = 0.094). In men, aPTT positively correlated with fT4 (r = 0.627; p < 0.05), while PT positively correlated with leukocyte-based inflammatory indices in women (p < 0.05). NSAID-treated patients had lower aPTTs and platelet counts than those treated with MPS (p < 0.05). Principal component analysis extracted "proinflammatory", "prothrombotic" and "antithrombotic" factors, but the "proinflammatory" factor was the independent predictor of elevated fT4 in women (OR = 2.705; p = 0.036). Conclusions: Our data demonstrated sex-specific associations of thyroid status and inflammatory biomarkers with hemostasis parameters in SAT. Routine hemostasis screening tests may help in monitoring the changes in the hemostasis system over the course of SAT.

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

Background

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

Methods

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

Results

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

Conclusion

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

Cerebral Venous Thrombosis during Thyrotoxicosis: Case Report and Literature Update

Cerebral venous thrombosis (CVT) is a rare cause of stroke, particularly in young adults. Several known thrombophilic conditions may lead to an increased CVT risk. Interestingly, few cases in the literature have reported an association between CVT and thyrotoxicosis. Here, we describe the case of a young woman with CVT and concomitant thyrotoxicosis, without any other known prothrombotic conditions. We also performed a literature review of CVT cases and hyperthyroidism, searching for all articles published in peer-reviewed journals. We identified 39 case reports/case series concerning patients with CVT associated with thyrotoxicosis, highlighting, in most cases, the association with additional known prothrombotic factors. We then discussed the possible mechanisms by which hyperthyroidism could underlie a pro-coagulative state resulting in CVT. Thyroid disease might be a more common prothrombotic risk factor than expected in determining CVT. However, in most cases, a coexistence of multiple risk factors was observed, suggesting a multifactorial genesis of the disorder. We hope that this work may alert clinicians to consider thyrotoxicosis as a potential risk factor for CVT, even in patients who apparently have no other pro-coagulative conditions.

Thyroid hormones and platelet activation in COVID-19 patients

PURPOSE

To retrospectively describe the association between thyroid hormones (TH) and platelet activation, as represented by mean platelet volume (MPV), in a cohort of patients hospitalized for COVID-19 with no known thyroid disease, and to correlate these data with the severity of COVID-19 and the occurrence of death/ARDS (Acute Respiratory Distress Syndrome).

METHODS

103 patients with real-time polymerase chain reaction (RT-PCR) testing-confirmed COVID-19 and hospitalized were enrolled. Serum samples were collected from patients upon admission before starting any treatment. Chi-squared test was used to determine the association between euthyroid sick syndrome (ESS) and COVID-19 severity. Multivariate logistic regression was performed to evaluate the best independent predictors of COVID-19 deaths/ARDS.

RESULTS

39/103 (37.9%) of patients were found to have ESS, and this condition was an independent predictor for the severity of COVID-19 (p = 0.003). Lower TSH and lower FT3/FT4 ratio correlated with higher MPV (p = 0,001 and p = 0.010), with an opposite trend with respect to what has been documented in non-COVID patients. Increasing MPV and lower FT3 significantly increased the risk, in COVID-19 patients, of an adverse outcome of death/ARDS.

CONCLUSION

Increased platelet activation, as represented by increased MPV, has already been reported to correlate with COVID-19 severity, possibly as a consequence of cytokine release. We demonstrated, in a cohort of 103 patients with COVID-19, that MPV is inversely correlated to TH levels, in particular in the case of ESS, where downregulation of TH axis may occur in case of systemic cytokine inflammation and more severe outcomes (death/ARDS). That ESS itself may directly cause platelet activation, as demonstrated by higher MPV in these patients, is an interesting hypothesis which deserves further investigation.

A Literature Review on SARS-CoV-2 and Other Viruses in Thyroid Disorders: Environmental Triggers or No-Guilty Bystanders?

A growing number of findings indicate a relationship between COVID-19 infection and thyroid dysfunction. This association is also strengthened by knowledge on the potential of viral infections to trigger thyroid disorders, although the exact underlying pathogenetic process remains to be elucidated. This review aimed to describe the available data regarding the possible role of infectious agents, and in particular of SARS-CoV-2, in the development of thyroid disorders, summarizing the proposed mechanisms and levels of evidence (epidemiological, serological or direct presence of the viruses in the thyroid gland) by which the infection could be responsible for thyroid abnormalities/diseases. Novel data on the association and mechanisms involved between SARS-CoV-2 vaccines and thyroid diseases are also discussed. While demonstrating a clear causal link is challenging, numerous clues at molecular and cellular levels and the large amount of epidemiological data suggest the existence of this relationship. Further studies should be taken to further investigate the true nature and strength of this association, to help in planning future preventive and therapeutic strategies for more personal and targeted care with attention to the underlying causes of thyroid dysfunction.

Possible Contributions of Nongenomic Actions of Thyroid Hormones to the Vasculopathic Complex of COVID-19 Infection

BACKGROUND

Integrin αvβ3 is a cell membrane structural protein whose extracellular domain contains a receptor for L-thyroxine (T4). The integrin is expressed in rapidly dividing cells and its internalization is prompted by T4. The protein binds viruses and we have raised the possibility elsewhere that action of free T4 (FT4)-when he latter is increased in the nonthyroidal illness syndrome (NTIS) known to complicate COVID-19 infecction-may enhance cellular uptke of SARS-CoV-2 and its receptor.

OBJECTIVE

Because T4 also acts nongenomically via the integrin to promote platelet aggregation and angiogenesis, we suggest here that T4 may contribute to the coagulopathy and endothelial abnormalities that can develop in COVID-19 infections, particularly when the lung is primary affected.

DISCUSSION AND CONCLUSIONS

Elevated FT4 has been described in the NTIS of COVID-19 patients and may be associated with increased illness severity, but the finding of FT4 elevation is inconsistent in the NTIS literature. Circulating 3,5',3'-triiodo-L-thyronine (reverse T3, rT3) are frequently elevated in NTIS. Thought to be biologically inactive, rT3in fact stimulates cancer cell proliferation via avb3 and also may increase actin polymerization. We propose here that rT3 in the NTIS complicating systemic COVIF-19 infection may support coagulation and disordered blood vessel formation via actin polymerization.

Thyroid Function During and After COVID-19 Infection: A Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can lead to multiorgan dysfunction through pulmonary and systemic inflammation. Infection also affects the thyroid gland directly via cytopathological effects of the virus or indirectly through cytokines, complement systems and coagulation mechanisms. The thyroid gland regulates innate and adaptive immune systems by genomic and nongenomic pathways. During or after SARS-CoV-2 infection, Graves' disease and subacute thyroiditis might be triggered, resulting in hyperthyroidism; alternatively, the effect of the virus on the hypophyseal.hypothalamic axis might cause central hypothyroidism. Severe cases of coronavirus disease 2019 (COVID-19) can present with hypoxia, which requires the use of dexamethasone. This can depress basal serum concentrations of 3,5,3'-triiodothyronine. Thyroid function should be monitored when using dexamethasone in patients with COVID-19. This article briefly reviews the direct and indirect effects of SARS-CoV-2 on the thyroid gland and function.

Impact of COVID-19 on the thyroid gland: an update

Coronavirus disease 2019 (COVID-19) is the pandemic of the new millennium. COVID-19 can cause both pulmonary and systemic inflammation, potentially determining multi-organ dysfunction. Data on the relationship between COVID-19 and thyroid have been emerging, and rapidly increasing since March 2020. The thyroid gland and the virus infection with its associated inflammatory-immune responses are known to be engaged in complex interplay. SARS-CoV-2 uses ACE2 combined with the transmembrane protease serine 2 (TMPRSS2) as the key molecular complex to infect the host cells. Interestingly, ACE2 and TMPRSS2 expression levels are high in the thyroid gland and more than in the lungs. Our literature search provided greater evidence that the thyroid gland and the entire hypothalamic-pituitary-thyroid (HPT) axis could be relevant targets of damage by SARS-CoV-2. Specifically, COVID-19-related thyroid disorders include thyrotoxicosis, hypothyroidism, as well as nonthyroidal illness syndrome. Moreover, we noticed that treatment plans for thyroid cancer are considerably changing in the direction of more teleconsultations and less diagnostic and therapeutical procedures. The current review includes findings that could be changed soon by new results on the topic, considering the rapidity of worldwide research on COVID-19.

Thyrotrophin and thyroxine support immune homeostasis in humans

The endocrine and the immune systems interact by sharing receptors for hormones and cytokines, cross‐control and feedback mechanisms. To date, no comprehensive study has assessed the impact of thyroid hormones on immune homeostasis. By studying immune phenotype (cell populations, antibody concentrations, circulating cytokines, adipokines and acute‐phase proteins, monocyte–platelet interactions and cytokine production capacity) in two large independent cohorts of healthy volunteers of Western European descent from the Human Functional Genomics Project (500FG and 300BCG cohorts), we identified a crucial role of the thyroid hormone thyroxin (T4) and thyroid‐stimulating hormone (TSH) on the homeostasis of lymphocyte populations. TSH concentrations were strongly associated with multiple populations of both effector and regulatory T cells, whereas B‐cell populations were significantly associated with free T4 (fT4). In contrast, fT4 and TSH had little impact on myeloid cell populations and cytokine production capacity. Mendelian randomization further supported the role of fT4 for lymphocyte homeostasis. Subsequently, using a genomics approach, we identified genetic variants that influence both fT4 and TSH concentrations and immune responses, and gene set enrichment pathway analysis showed enrichment of fT4‐affected gene expression in B‐cell function pathways, including the CD40 pathway, further supporting the importance of fT4 in the regulation of B‐cell function. In conclusion, we show that thyroid function controls the homeostasis of the lymphoid cell compartment. These findings improve our understanding of the immune responses and open the door for exploring and understanding the role of thyroid hormones in the lymphocyte function during disease.

Effects of oral contraceptives on thyroid function and vice versa

BACKGROUND

Thyroid gland dysfunction represents an epidemiologically relevant disease in the female gender, where treatment with oral contraceptives (OCs) is frequently prescribed. Although OCs are able to impact the thyroid gland function, scanty data have been released on this matter so far.

AIM

The aim of this article was to review how hormonal OCs, including estrogen- or progesterone-only containing medications, interact with the hepatic production of thyroid-binding globulin (TBG) and, consequently, their effects on serum levels of thyroxine (T4) and triiodothyronine (T3). We also reviewed the effect of Levo-T4 (LT4) administration in women taking OCs and how they influence the thyroid function in both euthyroid women and in those receiving LT4.

REVIEW

The estrogenic component of the pills is capable of increasing various liver proteins, such as TBG, sex hormone-binding protein (SHBG) and coagulation factors. On the other hand, the role of progestogens is to modulate estrogen-dependent effects mainly through their anti-androgenic action. In fact, a reduction in the effects of androgens is useful to keep the thromboembolic and cardiovascular risks low, whereas OCs increase it especially in women with subclinical hypothyroidism or in those treated with LT4. Accordingly, subclinical hypothyroidism is known to be associated with a higher mean platelet volume than normal and this increases cardiovascular risk due to platelet hyperactivity caused by incomplete thrombocytopoietic maturation.

Nongenomic Actions of Thyroid Hormone: The Integrin Component

The extracellular domain of plasma membrane integrin αvβ3 contains a cell surface receptor for thyroid hormone analogues. The receptor is largely expressed and activated in tumor cells and rapidly dividing endothelial cells. The principal ligand for this receptor is l-thyroxine (T₄), usually regarded only as a prohormone for 3,5,3'-triiodo-l-thyronine (T₃), the hormone analogue that expresses thyroid hormone in the cell nucleus via nuclear receptors that are unrelated structurally to integrin αvβ3. At the integrin receptor for thyroid hormone, T₄ regulates cancer and endothelial cell division, tumor cell defense pathways (such as anti-apoptosis), and angiogenesis and supports metastasis, radioresistance, and chemoresistance. The molecular mechanisms involve signal transduction via mitogen-activated protein kinase and phosphatidylinositol 3-kinase, differential expression of multiple genes related to the listed cell processes, and regulation of activities of other cell surface proteins, such as vascular growth factor receptors. Tetraiodothyroacetic acid (tetrac) is derived from T₄ and competes with binding of T₄ to the integrin. In the absence of T₄, tetrac and chemically modified tetrac also have anticancer effects that culminate in altered gene transcription. Tumor xenografts are arrested by unmodified and chemically modified tetrac. The receptor requires further characterization in terms of contributions to nonmalignant cells, such as platelets and phagocytes. The integrin αvβ3 receptor for thyroid hormone offers a large panel of cellular actions that are relevant to cancer biology and that may be regulated by tetrac derivatives.

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.

Is There a Role for Levo-Thyroxine for the Treatment of Arterial Erectile Dysfunction? The Clinical Relevance of the Mean Platelet Volume

BACKGROUND

Arterial erectile dysfunction (ED) is an early sign of vascular damage. Rare evidence has been published so far as to whether subclinical hypothyroidism (SCH) affects arterial erectile function. Therefore, the objective of this study was to fill this gap.

METHODS

Patients with arterial ED and SCH were consecutive enrolled and randomly divided into Group A (n = 20) and Group B (n = 20). Group A was treated with levo-thyroxine (LT4) at the dose of 1 µg/kg/day for six months, whereas patients of the group B did not receive any treatment. Thyroid stimulating hormone (TSH), free-thyroxine (FT4), peak systolic velocity (PSV), International Index of Erectile Function 5-item version (IIEF-5) score, mean platelet volume (MPV), and total cholesterol were evaluated at enrollment (T0) and after six months (T1). Patients without hypertension, diabetes mellitus, dyslipidemia, not on drugs, and with normal total testosterone (TT) values were included in this study.

RESULTS

Group A and B did not differ for age (61.2 ± 4.8 vs. 60.3 ± 5.6 years), body-mass index (28.7 ± 2.5 vs. 28.3 ± 2.6 Kg/m²), and serum TT levels (481.2 ± 54.0 vs. 492.1 ± 59.7 ng/dL). At T0, serum TSH levels (6.5 ± 1.2 vs. 6.0 ± 1.0 µIU/mL), FT4 (8.8 ± 0.6 vs. 8.8 ± 0.6 pmol/L), PSV (26.5 ± 1.4 vs. 25.8 ± 2.1 cm/s), IIEF-5 score (8.2 ± 1.7 vs. 9.0±1.7), and total cholesterol (167.8 ± 21.7 vs. 171.6 ± 21.3 mg/dL) did not significantly differ in patients of Group A vs. those of Group B. MPV was significantly higher in Group A than in Group B (12.3 ± 0.3 vs. 11.8±0.7 fL). At T1, Group A showed significantly lower TSH (2.26 ± 0.5 µIU/mL), MPV (9.5 ± 0.3 fL), and total cholesterol (137.8 ± 29.2 mg/dL) and significantly higher FT4 (9.3 ± 0.4 pmol/L), PSV (40.0 ± 2.6 cm/s), and IIEF-5 score (20.2 ± 3.6) compared to pre-treatment values. None of these endpoints showed significant change at T1 compared to T0 in patients of group B.

CONCLUSIONS

Lt4 therapy is associated with an improvement of the erectile function at the vascular level, a decrease in MPV and total cholesterol. LT4 therapy should be considered in patients with arterial ED and SCH.

Platelet ATP, Thyroid Hormone Receptor on Integrin αvβ3 and Cancer Metastasis

Activated platelets may contribute to the metastatic behavior of tumor cells when the cancer cells and platelets interact. The interaction requires cell and platelet surface integrin. Thyroid hormone as L-thyroxine (T4) is the principal ligand for a hormone receptor on integrin αvβ3 on tumor cells and platelets. T4 activates the integrin, promoting platelet aggregation and degranulation (local ATP release) and stimulating tumor cell proliferation. By a variety of molecular mechanisms reviewed here, extracellular ATP promotes tumor cell invasiveness and metastasis and supports a role for T4 as a pro-metastatic factor.

Anticoagulation in Venous Thromboembolism Prophylaxis in Medically Ill Patients: Potential Impact of NOACs

While substantial evidence supports the use of standard-duration injectable anticoagulants for venous thromboembolism (VTE) prophylaxis, consensus is mixed about which agents may be preferred in acutely ill patients with ongoing need of VTE prophylaxis past the first 10-day duration of hospital stay and post-discharge. Non-vitamin K antagonist oral anticoagulants (NOACs) provide Factor Xa inhibition to prevent the thrombin generation essential in thromboembolism development, but evidence for the efficacy and safety of most NOACs is conflicting regarding extended-duration prophylaxis. Enoxaparin, a preferred injectable anticoagulant in standard-duration VTE prophylaxis, has shown an increased risk of major bleeding events when used in extended-duration prophylaxis, which outweighs its benefit. Rivaroxaban has demonstrated efficacy in extended-duration prophylaxis, but both rivaroxaban and apixaban have shown increased risks of major bleeding. Betrixaban remains the only NOAC approved in the USA for extended-duration VTE prophylaxis, and it demonstrates efficacy, with fewer adverse effects than other NOACs. This review evaluates the appropriateness of different NOAC agents compared with current therapies for the extended-duration VTE prophylaxis setting in medically ill populations.