Elevated thrombin activatable fibrinolysis inhibitor (TAFI) antigen levels in overt and subclinical hypothyroid patients were reduced by levothyroxine replacement

Association Between Nonthyroidal Illness Syndrome and Disseminated Intravascular Coagulation in Sepsis

Purpose

Both nonthyroidal illness syndrome (NTIS) and disseminated intravascular coagulation (DIC) are commonly occurred in sepsis. The objective of this study is to evaluate the association between NTIS and DIC, as well as their impacts on the mortality in adults with sepsis.

Patients and methods

A total of 1219 septic patients in two Chinese academic centers from October 2012 and October 2022 were enrolled in analysis. We conduct logistic regression models to analyze the independent risk factors for DIC. Modified Poisson regression models are used to estimate the relative risk (RR) of NTIS on the 28 days mortality in septic patients with DIC. Correlation analysis between thyroid function parameters and coagulation parameters is performed with Pearson coefficient be reported.

Results

DIC is diagnosed on 388 (31.8%) of all the 1219 enrolled septic patients within 72 hours after admission. In multivariate logistic regression models, NTIS (OR 3.19; CI 2.31-4.46; p<0.001) is a statistically significant independent risk factor for DIC after adjustment for potential confounders. Twenty-eight days mortality is significantly higher in DIC patients complicated with NTIS compared with the other DIC patients (23.2% vs 14.0%, p=0.024). This result is also robust in different modified Poisson regression models (Model 1: RR 1.46; CI 1.25-1.70; p<0.001; Model 2: RR 1.35; CI 1.14-1.60; p<0.001; Model 3: RR 1.18; CI 1.02-1.37; p=0.026). Correlation analysis reveals that the thyroid function parameters of FT3, FT4 and TSH only have weak correlations with coagulation parameters of platelet count, fibrinogen, FDP, D-dimers, PT, APTT and INR in sepsis.

Conclusion

NTIS is an independent risk factor for DIC in adults with sepsis. DIC patients complicated with NTIS have significantly higher severity and higher rate of mortality.

Hypothyroidism as an Independent Predictor of 30-day Readmission in Head and Neck Cancer Patients

OBJECTIVES

To define the role of hypothyroidism and other risk factors for unplanned readmissions after surgery for head and neck cancer.

STUDY DESIGN

Retrospective cohort study.

METHODS

The Nationwide Readmission Database (NRD) was used to identify patients who underwent surgery for mucosal head and neck cancer (oral cavity, oropharynx, larynx, and hypopharynx) between 2010 and 2017. Univariate and multivariate logistic regression were performed to determine patient, tumor, and hospital related risk factors for 30-day readmission. Readmitted patients were stratified by preoperative diagnosis of hypothyroidism to compare readmission characteristics.

RESULTS

For the 131,013 patients who met inclusion criteria, the readmission rate was 15.9%. Overall, 11.91% of patients had a preoperative diagnosis of hypothyroidism. After controlling for other variables, patients with a preoperative diagnosis of hypothyroidism had 12.2% higher odds of readmission compared to those without hypothyroidism (OR: 1.12, 1.03-1.22, p = 0.008). Patients with hypothyroidism had different reasons for readmission, including higher rates of wound dehiscence, fistula, infection, and electrolyte imbalance. Among readmitted patients, the length of stay for index admission (mean 10.5 days vs. 9.2 days, p < 0.001), readmission (mean 7.0 vs. 6.6 days, p = 0.05), and total hospital charge were higher for hypothyroid patients ($137,742 vs. $119,831, p < 0.001).

CONCLUSION

Hypothyroidism is an independent risk factor for 30-day readmission following head and neck cancer resection. Furthermore, hypothyroid patients are more likely to be readmitted for wound complications, infection, and electrolyte imbalance. Targeted interventions should be considered for hypothyroid patients to decrease readmission rates and associated patient morbidity, potentially leading to earlier initiation of adjuvant treatment.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:2988-2998, 2023.

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.

Novel Causal Plasma Proteins for Hypothyroidism: A Large-scale Plasma Proteome Mendelian Randomization Analysis

CONTEXT

Although several risk proteins for hypothyroidism have been reported in recent years, many more plasma proteins have not been tested.

OBJECTIVE

To determine potential mechanisms and novel causal plasma proteins for hypothyroidism using Mendelian randomization (MR).

METHODS

A large-scale plasma proteome MR analysis was conducted using protein quantitative trait loci (pQTLs) for 2297 plasma proteins. We classified pQTLs into 4 different groups. MR analyses were conducted within the 4 groups simultaneously. Significant proteins were discovered and validated in 2 different cohorts. Colocalization analysis and enrichment analysis were conducted using proteins found with MR.

RESULTS

Thirty-one proteins were identified in the discovery cohort. Among them, 13 were validated in the validation cohort. Nine of the 13 proteins are risk factors (ISG15, Fc receptor-like protein 2, tumor necrosis factor ligand superfamily member 14, Rab-2A, FcRL3, thrombomodulin, interferon [IFN]-lambda-1, platelet glycoprotein Ib alpha chain, IL-7RA) for hypothyroidism, whereas others are protective proteins (protein O-glucosyltransferase 1 [POGLUT1], tumor necrosis factor ligand superfamily, 3-hydroxyisobutyryl-CoA hydrolase, transferrin receptor protein 1). Among the significant proteins, POGLUT1 strongly colocalized with expression quantitative trait loci from whole blood (posterior probability of colocalization [PP4] = 0.978) and the thyroid (PP4 = 0.978). Two different trans-pQTLs (rs2111485 PP4 = 0.998; rs35103715 PP4 = 0.998) for IFN-lambda-1 strongly colocalized with hypothyroidism in different chromosomes.

CONCLUSION

Thirteen various proteins were identified and validated to be associated with hypothyroidism using univariable MR. We reinforced and expanded the effect of IFN on hypothyroidism. Several proteins identified in this study could explain part of the association between the coagulation system and hypothyroidism. Our study broadens the causal proteins for hypothyroidism and provides the relationships between plasma proteins and hypothyroidism. The proteins identified in this study can be used as early screening biomarkers for hypothyroidism.

The Effect of Subclinical Hypothyroidism on Coagulation and fibrinolysis: A Systematic Review and Meta-Analysis

BACKGROUND

Despite patients with thyroid dysfunction show obvious abnormal hemostatic indicators in the peripheral blood, the current research on whether and how subclinical hypothyroidism (SCH) influence hemostatic function (the coagulation and fibrinolytic system) still remains controversial.

OBJECTIVE

We conducted this study to evaluate how SCH influence on the coagulation and fibrinolytic system in human body.

METHODS

Prior to March 2022, Web of Science, Embase, PubMed, WanFang, CNKI data and reference lists were searched to identify eligible researches. Two of us independently extracted the data and evaluated study quality. The effect size is represented by standard mean difference (SMD). Both fixed and random-effects models were used where appropriate. Review Manager 5.3 and STATA 16.0 were used to analyze the eligible data.

RESULTS

1325 patients from twelve observational studies were involved in our research. Our study revealed that SCH changed the heamostatic balance towards hypercoagulable and hypofibrinolytic conditions accompanied by an increase in tissue fibrinogen, plasminogen activator and plasminogen activator inhibitor-1. By contrast, there was no statistically difference in acivated partial thromboplastin time (APTT) and D-Dimer in SCH group compared with that in control subjects.

CONCLUSIONS

Our study confirmed that SCH is related with a prothrombotic state, as reflected by changes in both coagulation and fibrinolysis. It is highly recommended for screening cardiovascular risk factors in combination with an adequate evaluation of SCH state.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk/prospero/#recordDetails] PROSPERO [CRD42021275313].

Venous thromboembolism rates and risk factors following endoscopic skull base surgery

BACKGROUND

Venous thromboembolism (VTE) is a potentially fatal perioperative complication. The objective of this study was to assess the rate and risk factors for VTE in endoscopic skull base surgery (ESBS).

METHODS

This was a retrospective review of adults undergoing ESBS at a tertiary academic center. Incidence of VTE in the 30-day postoperative period was recorded. Logistic regression analyses identified factors associated with VTE.

RESULTS

1122 ESBS cases between 2009 and 2019 were studied. Almost no cases (96.1%) employed perioperative VTE chemoprophylaxis. The overall incidence of VTE was 2.3% (26/1122). Malignant pathologies had a higher rate of VTE compared to nonmalignant pathologies (4.5% vs 2.0%, OR 2.85, 95%CI 1.22-6.66). Factors associated with an increased risk of VTE included a Caprini score greater than 5 (OR 1.53, 95% CI 1.28-1.83); multiple preoperative endocrinopathies such as the syndrome of inappropriate antidiuretic hormone secretion (SIADH) (OR 22.48, 95% CI 3.93-128.70), adrenal insufficiency (OR 5.24, 95% CI 1.82-15.03), hypercortisolism (OR 4.46, 95% CI 1.47-13.56), and hypothyroidism (OR 3.69, 95% CI 1.66-8.20), each 10-hour increment of lumbar drain duration (OR 1.16, 95%CI 1.08-1.25), and each 10-hour increment for duration of hospitalization (OR 1.05, 95% CI 1.03-1.06).

CONCLUSIONS

The incidence of VTE following ESBS is relatively low. Factors with a higher association with VTE include malignancy, preoperative endocrinopathies, higher Caprini score, prolonged lumbar drain duration, and prolonged hospitalization. Further study is needed to validate these findings and to refine clinical decision making around perioperative VTE prophylaxis. This article is protected by copyright. All rights reserved.

Association of TAFI gene polymorphisms with severity of coronary stenosis in stable coronary artery disease

INTRODUCTION

Coronary stenosis is a consequence of atherosclerotic plaque progression that is associated with impaired fibrinolysis. Thrombin-activatable fibrinolysis inhibitor (TAFI) and plasminogen activator inhibitor 1 (PAI-1) are fibrinolysis inhibitors whose levels are influenced by acquired conditions and by polymorphisms. This study therefore aimed to investigate the association of TAFI and PAI-1 gene polymorphisms with severity of coronary stenosis in subjects with stable coronary artery disease (CAD).

MATERIALS AND METHODS

A total of 327 subjects suspected with CAD who underwent a coronary angiogram were recruited. Gensini score was applied to stratify the severity of coronary stenosis. Based on the Gensini score, the subjects were categorized into low-medium (<20) or high (≥20) groups. The study polymorphisms included TAFI Ala147Thr (505G/A), Thr325Ile (1040C/T), +1542C/G, +1583T/A and PAI-1 -675 4G/5G. Most polymorphisms were genotyped by allele-specific polymerase chain reaction, except for TAFI Thr325Ile that was genotyped by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

A significant increase in the Gensini score was found in TAFI 505A and +1583A allele carriers. Binary regression analysis revealed the independent association of the TAFI 505G/A and +1583T/A polymorphisms with a high Gensini score [adjusted OR = 1.67 (95% CI: 1.03, 2.73) and 1.69 (95% CI: 1.04, 2.76), respectively]. Neither the homozygous PAI-1 -675 4G/4G nor the heterozygous 4G/5G was associated with a high Gensini score.

CONCLUSIONS

The results indicated the contribution of TAFI polymorphisms to atherosclerosis progression and severity of coronary stenosis in stable CAD.

The influence of thyroid function on the coagulation system and its clinical consequences

Several studies indicate that low plasma levels of thyroid hormone shift the hemostatic system towards a hypocoagulable and hyperfibrinolytic state, whereas high levels of thyroid hormone lead to more coagulation and less fibrinolysis. Low levels of thyroid hormone thereby seem to lead to an increased bleeding risk, whereas high levels, by contrast, increase the risk of venous thromboembolism. Hypothyroidism leads to a higher incidence of acquired von Willebrand's syndrome and with increasing levels of free thyroxine, levels of fibrinogen, factor VIII and von Willebrand factor, amongst others, increase gradually, to the extent that they may lead to symptomatic venous thromboembolism in patients with hyperthyroidism. Here, we discuss the literature on the effect of thyroid hormone on the hemostatic system and the associated risk of bleeding and venous thromboembolism. Patients with hypothyroidism are at increased risk of developing bleeding complications, which could be relevant in patients undergoing invasive procedures. Furthermore, physicians should be aware of the possibility of hyperthyroidism as an underlying risk factor for venous thromboembolism, especially in unexplained cases. Clinical studies are needed to further investigate the significance for general practice of these findings. Besides the effects of hyperthyroidism on venous thromboembolism, its effects on embolism secondary to atrial fibrillation are described.

Thrombin-activatable fibrinolysis inhibitor in hypothyroidism and hyperthyroxinaemia

Endocrine disorders affect both the coagulation and fibrinolytic systems, and have been associated with the development of cardiovascular diseases. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a link between coagulation and the fibrinolytic system. The aim of this study was to determine the effect of thyroid hormone excess and deficiency on TAFI levels and function. The effect of hyperthyroxinemia on TAFI was studied in healthy volunteers who were randomised to receive levothyroxine or no medication for 14 days in a crossover design. The effect of hypothyroidism on TAFI was studied in a multicentre observational cohort study. Blood was drawn before treatment of patients with newly diagnosed hypothyroidism and when euthyroidism was achieved. Plasma clot-lysis times, activated TAFI (TAFIa)-dependent prolongation of clot-lysis and TAFI levels were measured. Thyroid hormone excess resulted in a hypofibrinolytic condition and in an enhanced TAFIa-dependent prolongation of clot lysis. A trend towards decreased plasma TAFI levels was observed in healthy volunteers who used levothyroxine. Hypothyroidism resulted in hyperfibrinolysis and a reduced TAFIa-dependent prolongation of clot lysis. In conclusion, alterations of TAFIa-dependent prolongation of clot lysis in patients with thyroid disorders may cause an impaired haemostatic balance. The disturbed haemostatic balance in patients with hyperthyroidism might make them prone to thrombosis, while the risk for bleeding may increase in patients with hypothyroidism.

Hemostasis in Hypothyroidism and Autoimmune Thyroid Disorders

CONTEXT

There are contradictory results on the effect of hypothyroidism on the changes in hemostasis. Inadequate population-based studies limited their clinical implications, mainly on the risk of venous thromboembolism (VTE). This paper reviews the studies on laboratory and population-based findings regarding hemostatic changes and risk of VTE in hypothyroidism and autoimmune thyroid disorders.

EVIDENCE ACQUISITION

A comprehensive literature search was conducted employing MEDLINE database. The following words were used for the search: Hypothyroidism; thyroiditis, autoimmune; blood coagulation factors; blood coagulation tests; hemostasis, blood coagulation disorders; thyroid hormones; myxedema; venous thromboembolism; fibrinolysis, receptors thyroid hormone. The papers that were related to hypothyroidism and autoimmune thyroid disorder and hemostasis are used in this review.

RESULTS

Overt hypothyroidism is more associated with a hypocoagulable state. Decreased platelet count, aggregation and agglutination, von Willebrand factor antigen and activity, several coagulation factors such as factor VIII, IX, XI, VII, and plasminogen activator-1 are detected in overt hypothyrodism. Increased fibrinogen has been detected in subclinical hypothyroidism and autoimmune thyroid disease rendering a tendency towards a hypercoagulability state. Increased factor VII and its activity, and plasminogen activator inhibitor-1 are among several findings contributing to a prothrombotic state in subclinical hypothyroidism.

CONCLUSIONS

Overt hypothyroidism is associated with a hypocoagulable state and subclinical hypothyroidism and autoimmune thyroid disorders may induce a prothrombotic state. However, there are contradictory findings for the abovementioned thyroid disorders. Prospective studies on the risk of VTE in various levels of hypofunctioning of the thyroid and autoimmune thyroid disorders are warranted.

The effects of pituitary and thyroid disorders on haemostasis: potential clinical implications

Disturbances of coagulation and fibrinolysis are usually multifactorial and growing evidence suggests that endocrinopathies modulate the haemostatic balance. The thrombotic alterations in endocrine disorders range from mild laboratory clotting abnormalities with little clinical significance to serious thrombotic and bleeding disorders directly related to hormonal disturbances. This literature review focuses on presenting the current data on the effects of thyroid and pituitary disorders on various parameters of the haemostatic system. With the exception of overt hypothyroidism which appears to cause a bleeding tendency, the rest of the endocrinopathies discussed in this review (subclinical hypothyroidism, hyperthyroidism, endogenous hypercortisolaemia, growth hormone deficiency, acromegaly, prolactinoma/hyperprolactinaemia and hypogonadotrophic hypogonadism) are associated with a hypercoagulable and hypofibrinolytic state, increasing the overall cardiovascular risk and thromboembolic potential in these patients. In most studies, the haemostatic abnormalities seen in endocrine disorders are usually reversible with successful treatment of the underlying condition and biochemical disease remission. High-quality studies on larger patient cohorts are needed to produce robust evidence on the effects of endocrine disorders and their therapeutic interventions on coagulation and fibrinolysis, as well as on the long-term mortality and morbidity outcomes in association with endocrine-related haemostatic imbalance. Given the rarity of some of the endocrine disorders, multicentre studies are required to achieve this target.

Effect of magnesium sulfate and thyroxine on inflammatory markers in a rat model of hypothyroidism

Inflammation is a major risk factor for cardiovascular complications. Magnesium sulfate (MgSO4) has anti-inflammatory actions. Therefore we investigated the effects of levothyroxine and MgSO4 on inflammatory markers as C-reactive protein (CRP), interleukin-6, tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in hypothyroid rats. Sixty male rats were divided into 6 groups; normal, normal + MgSO4, hypothyroidism, hypothyroidism + levothyroxine, hypothyroidism + MgSO4, and hypothyroidism + levothyroxine + MgSO4. Thyroxine, triiodothyronine, and thyroid-stimulating hormone (TSH), CRP, interleukin-6, TNF-α, ICAM-1, and VCAM-1 were measured in all rats. Hypothyroidism significantly increased TSH, CRP, interleukin-6, TNF-α, ICAM-1, and VCAM-1 and decreased triiodothronine and thyroxine. Treatment of hypothyroid rats with levothyroxine or MgSO4 significantly decreased CRP, interleukin-6, TNF-α, ICAM-1, and VCAM-1. Combined therapy of hypothyroid rats with levothyroxine and MgSO4 significantly decreased CRP, interleukin-6, TNF-α, ICAM-1, and VCAM-1 compared with hypothyroid rats either untreated or treated with levothyroxine or MgSO4. This study demonstrates that hypothyroid rats have chronic low grade inflammation, which may account for increased risk of cardiovascular diseases. Combined levothyroxine and MgSO4 is better than levothyroxine or MgSO4 alone in alleviating the chronic low grade inflammatory status and therefore reducing the risk of cardiovascular diseases in hypothyroid animals.

Prothrombotic alterations in plasma fibrin clot properties in thyroid disorders and their post-treatment modifications

INTRODUCTION

Available data on fibrin clot properties and fibrinolysis in hyperthyroidism and hypothyroidism are inconsistent. Our objective was to assess the impact of effective treatment of hyper- and hypothyroidism on fibrin clot characteristics.

MATERIAL AND METHODS

In a case-control study, ex vivo plasma fibrin clot permeability (Ks) and efficiency of fibrinolysis were assessed in 35 consecutive hyperthyroid and 35 hypothyroid subjects versus 30 controls. All measurements were performed before and after 3months of thyroid function normalizing therapy.

RESULTS

At baseline, hyperthyroid, but not hypothyroid, patients had lower Ks than controls (p<0.0001). Hyperthyroid and hypothyroid groups compared with controls had prolonged clot lysis time (CLT), and lower rate of D-dimer release from clots (D-Drate) (all p<0.05). The regression analysis adjusted for fibrinogen showed that in hyperthyroid patients, pre-treatment thyroid stimulating hormone (TSH) independently predicted Ks, while thrombin activatable fibrinolysis inhibitor (TAFI) antigen predicted CLT. In hypothyroid individuals a similar regression model showed that TSH independently predicts CLT. After 3months of thyroid function normalizing therapy, 32 (91.4%) hyperthyroid and 30 (85.7%) hypothyroid subjects achieved euthyroidism and had improved fibrin clot properties (all p<0.05), with normalization of Ks in hyperthyroid and lysability in hypothyroid patients.

CONCLUSIONS

Both hyper- and mild-to-moderate hypothyroidism are associated with prothrombotic plasma fibrin clot phenotype and restoration of euthyroidism improves clot phenotype. Abnormal fibrin clot phenotype might contribute to thromboembolic risk in thyroid disease.

Subclinical hypothyroidism: Comparison of adhesion molecule levels before and after levothyroxine therapy

OBJECTIVE

Adhesion molecules are involved in inflammation, atherosclerosis and malignancy. This study measured levels of adhesion molecules before and after levothyroxine therapy in patients with subclinical hypothyroidism (SHO).

METHODS

Levels of soluble (s) intracellular adhesion molecule (ICAM)-1, s vascular cell adhesion molecule (sVCAM) VCAM-1 and sE-selectin were analysed in patients diagnosed with SHO, prior to administration of 50 µg/day levothyroxine orally for 3 months. Subsequently, levels of sICAM-1, sVCAM-1 and sE-selectin were reanalysed then compared with the pretreatment levels.

RESULTS

In 30 patients with SHO, levels of sICAM-1 were found to be significantly higher than those in healthy controls, (P = 0.001). Post-treatment sICAM-1 levels were significantly lower than pretreatment levels (P = 0.001). No significant differences were found in sVCAM-1 or sE-selectin levels between healthy controls and patients with SHO before treatment, or between patients with SHO pre- and post-treatment.

CONCLUSIONS

Patients with SHO had significantly higher levels of sICAM-1 compared with controls. Levels became normal after treatment with levothyroxine. These findings emphasize the need for levothyroxine therapy in cases of SHO to normalize sICAM-1 levels. Such treatment helps to prevent the future development of atherosclerosis or cancer.

Optimal treatment of hypothyroidism associated with live birth in cases of previous recurrent placental abruption and stillbirth

OBJECTIVE

To examine the clinical management of and placentas from pregnant women with hypothyroidism and obstetric history of recurrent stillbirth in order to identify possible etiologic mechanisms.

METHODS

Two cases involving 26-year-old women with hypothyroidism and history of recurrent stillbirth are reported. Placentas from all of the women's pregnancies were compared in order to identify histologic similarities.

RESULTS

In both cases, multifocal hemorrhagic infarctions and abruptions were seen, indicating progressive uteroplacental ischemic damage leading to stillbirth. Thrombophilia, infection, and diabetes tests were all negative. With meticulous monitoring and normalization of thyroid function by end of first/early second trimester in subsequent pregnancies, there were live births and no evidence of infarction on placental histology.

CONCLUSION

The 2 reported cases raise the possibility of uteroplacental ischemia and placental abruption being mechanisms by which hypothyroidism can lead to stillbirth; they also highlight the potential of minimizing this risk via adequate levothyroxine treatment from early pregnancy.

Increased thrombin-activatable fibrinolysis inhibitor and decreased tissue factor pathway inhibitor and thrombomodulin levels in children with hypothyroidism

OBJECTIVE

We determined the profile of coagulation/fibrinolytic and vascular endothelial cell function parameters including plasminogen activator inhibitor (PAI) and thrombin-activatable fibrinolysis inhibitor (TAFI), tissue factor pathway inhibitor (TFPI), thrombomodulin (TM), and tissue plasminogen activator (tPA) levels in children with hypothyroidism.

METHODS

Forty children with hypothyroidism aged 0-16 months who presented for the first time to our hospital and 29 age-and sex-matched healthy controls were enrolled in the study. All coagulation tests were performed with ELISA method. One year after Na-L-thyroxine treatment, the study parameters were re-evaluated in 25 euthyroid children out of the 40 patients diagnosed with hypothyroidism.

RESULTS

Although no significant effect was detected regarding PAI antigen (Ag) and tPA Ag, the levels of TAFI, TM, and TFPI were consistent with subclinical hypercoagulability and hypofibrinolysis. There was a significant increase in TAFI Ag levels and a significant decrease in TFPI Ag and TM Ag levels in hypothyroid patients compared to healthy controls. As a result of correlation tests, the largest impact of hypothyroidism on coagulation system was on TFPI. In accordance with these findings, TAFI Ag levels decreased and TFPI Ag and TM Ag levels increased with hormonal replacement therapy.

CONCLUSIONS

Increased TAFI and decreased TFPI and TM in patients with hypothyroidism may indicate a potential hypercoagulable and hypofibrinolytic state as well as possible endothelial dysfunction, which may increase the risk of atherosclerotic and atherothrombotic complications. Thyroid hormone levels should also be checked in patients with a predisposition to coagulation, and thyroid replacement therapy should be initiated.

Aortic thrombosis in dogs: presentation, therapy, and outcome in 26 cases

OBJECTIVES

The pathogenesis and presentation of aortic thrombosis (AT) in dogs is not well characterized and an effective antithrombotic therapy for AT in dogs has not been identified. Our goal is to report the clinical presentation and results of therapies in dogs with AT.

ANIMALS

Twenty-six client-owned dogs.

METHODS

Retrospective review of medical records of dogs diagnosed with AT between 2003 and 2010.

RESULTS

Twenty-six dogs had an apparent primary mural aortic thrombus. None had structural heart disease at diagnosis. Twenty dogs were ambulatory with varying degrees of pelvic limb dysfunction. Duration of ambulatory dysfunction was 7.8 weeks (range 1 day-52 weeks). A majority of dogs (58%) had no concurrent conditions at diagnosis. Fourteen dogs were treated with a standard warfarin protocol for a median period of 22.9 months (range 0.5-53 months). Ambulatory function improved in all dogs treated with warfarin. Time until clinical improvement was 13.9 days (range 2-49 days). Dogs treated with warfarin did not become non-ambulatory, die or undergo euthanasia related to AT, or have a known serious hemorrhagic event.

CONCLUSIONS

The pathogenesis of AT in dogs is distinct from that of aortic thromboembolism (ATE) in cats. Aortic thrombosis in dogs is more likely to involve local thrombosis in the distal aorta with embolization to the arteries of the pelvic limb resulting in chronic progressive ambulatory dysfunction. Chronic warfarin administration is well-tolerated and appears to be an effective short-term and long-term therapy for dogs with AT.

Can subclinical hypothyroidism explain some sudden deaths due to pulmonary embolism without evident risk factors?

Thyroid pathology is rarely involved in the pathogenesis of sudden death in young people, and usually, when this is the case, is associated with acute changes of thyroid hormone blood levels. Three main thyroid causes of sudden death are known and used in tanathologic chains: thyrotoxicosis, myxedematous coma and, as of recently, lymphocytic thyroid infiltration. Coagulation disorders associated with thyroid disease are usually mild and not associated with sudden death. There are some studies showing an increased risk for unprovoked deep venous thrombosis in patients with hypothyroidism but there is none, to our knowledge, showing a correlation between hypothyroidism, deep venous thrombosis and sudden death. Our article suggests that subclinical hypothyroidism can lead to coagulation disorders and deep venous thrombosis which can explain some cases of sudden death associated with pulmonary embolism without other significant risk factors.

Thrombin-Activatable Fibrinolysis Inhibitor (TAFI) Antigen and Activity Assay in Patients With Primary Hypothyroidism

Hypothyroidism causes a tendency for cardiovascular diseases. It was recently shown that thrombin-activatable fibrinolysis inhibitor (TAFI) attenuates fibrinolysis and also fibrin-plasminogen interaction by the removal of lysine and arginine residues from fibrin monomers. The aim of this study was to determine the effects of overt hypothyroidism on the levels of TAFI antigen (TAFI Ag) and TAFI activity (TAFIa). Thirty-one overt primary hypothyroid patients and age- and gender-matched 25 healthy controls were enrolled in the study. Patients were treated with L-thyroxine after the collection of blood samples. Thyroid functions were reevaluated following the achievement of euthyroid status. Thrombin-activatable fibrinolysis inhibitor Ag, tissue plasminogen activator (t-PA), and plasminogen activator inhibitor 1 (PAI-1) levels were measured with the enzyme-linked immunosorbent assay (ELISA). Thrombin-activatable fibrinolysis inhibitor activity was assessed with the chromogenic assay. Thrombin-activatable fibrinolysis inhibitor Ag (1.63% ± 0.42% vs 1.32% ± 0.36%, P < .01) and TAFIa (14.2 ± 4.12 vs 11.6 ± 3.49 μg/mL, P < .05) levels were elevated in hypothyroid patient compared to controls. Plasminogen activator inhibitor 1 and t-PA levels were not significantly different between both groups. In hypothyroid patients, TAFI Ag levels were correlated with free T4 (r = -.373, P < .05) and thyroid-stimulating hormone (TSH) levels (r = .748, P < .001). Regression analysis showed that TSH levels were predictors of TAFI Ag levels (P < .001, β =.671, 95% confidence interval [CI]: 0.008-0.017). Following L-thyroxine treatment, TAFI Ag (1.63% ± 0.42%, 1.34% ± 0.33%, P < .05) and TAFIa (14.2 ± 4.12 μg/mL, 12.0 ± 2.77 μg/mL, P < .05) levels were significantly decreased, but t-PA and PAI-1 levels remained unchanged. This results point out that the fibrinolytic activity was decreased in hypothyroid patients, and therefore the achievement of euthyroid status is important in ameliorating the increased risk of cardiovascular disease.

Levothyroxine (LT4) suppression treatment for benign thyroid nodules alters coagulation

OBJECTIVE

Endogenous hyperthyroidism is associated with altered coagulation. The aim of the present study is to investigate the effect of levothyroxine (LT(4)) suppression treatment for benign thyroid nodules on coagulation system.

DESIGN

Prospective case-control study. Patients Thirty consecutive euthyroid pre-menopausal women with nodular goitre disease and 28 healthy controls were included in the study.

MEASUREMENTS

Plasma fibrinogen, d-dimer, von Willebrand factor (vWF), tissue factor (TF), tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI-1) and tissue factor pathway inhibitor (TFPI) levels were measured at baseline and after LT(4) suppression therapy.

RESULTS

Plasma levels of fibrinogen, d-dimer, vWF, TF and PAI-1 increased significantly after treatment with LT(4) for 1 year. Serum FT(4) was a significant predictor of increased fibrinogen, vWF and PAI-1 levels, when the data was controlled for age and BMI.

CONCLUSIONS

Our results suggest that LT(4) suppression therapy for benign thyroid nodules is associated with enhanced coagulation.

Hypothyroidism in postradiation head and neck cancer patients: incidence, complications, and management

PURPOSE OF REVIEW

To describe the incidence, risk factors, prevention, and management of hypothyroidism among patients treated with radiation and other modalities for head and neck cancers.

RECENT FINDINGS

Hypothyroidism may occur in up to 48% of patients treated for head and neck malignancies. It has been observed after radiation, surgery, and combined-modality therapies. The onset of hypothyroidism may be as early as 4 weeks and as late as 5 or 10 years after completion of therapy. It has been associated with poor wound healing, bleeding disorders, and a number of other potential complications germane to the practice of head and neck surgery. There is some evidence to suggest a protective role of hypothyroidism with respect to disease control survival in head and neck and other cancers.

SUMMARY

Hypothyroidism is common after treatment of head and neck cancers. Thyroid function studies should be obtained prior to and at regular intervals after treatment. Prompt recognition and intervention may prevent or reverse adverse physiological outcomes. Further studies are necessary to evaluate the role of permissive hypothyroidism in the context of treated head and neck malignancies.

Coagulation and fibrinolysis in thyroid dysfunction

Various abnormalities of hemostasis, ranging from subclinical laboratory abnormalities to clinically significant disorders of hemostasis, and rarely major hemorrhage or thromboembolism, may occur in patients with thyroid diseases. The objective of this review is to discuss the relationships between thyroid dysfunction and hemostasis (primary hemostasis and coagulation/fibrinolytic system). According to the recent literature, most of the hemostatic abnormalities associated with thyroid dysfunction are the consequences of direct effects of thyroid hormones on the synthesis of various hemostatic parameters. Thyroid autoimmunity may also modify the processes of primary and secondary hemostasis. We have concluded that hyperthyroidism is generally associated with hypercoagulability and hypofibrinolysis, whereas the hemostatic profile in hypothyroidism depends on the severity of the disease. As few data are available on hemostasis in subclinical thyroid disease, further studies on this subject are needed.

Increased thrombin-activatable fibrinolysis inhibitor and decreased tissue factor pathway inhibitor in patients with hypothyroidism

Various abnormalities of coagulation-fibrinolytic system have been reported in patients with thyroid dysfunction. Several studies indicate that coagulation and fibrinolytic system is disturbed in the patients with hypothyroidism. Also, the influence of hypothyroidism on hemostasis is controversial; both hypocoagulable and hypercoagulable states have been reported. The levels of plasma thrombin-activatable fibrinolysis inhibitor (TAFI) antigen and tissue factor pathway inhibitor (TFPI) have been investigated only once in patients with hypothyroidism. Therefore, the main purpose of this study was to evaluate the profile of coagulation and fibrinolytic parameters including TAFI and TFPI in patients with hypothyroidism. Fifteen patients with untreated hypothyroidism and 15 age-matched healthy controls were included in the study. Factors V(FV), VII (FVII), VIII (FVIII) activities, von Willebrand factor (vWF), protein C, protein S, thrombomodulin (TM), TFPI, and TAFI were measured. The relationships between serum thyroid hormones and these hemostatic parameters were examined. Compared with the control subjects, FVII activity, and TM Ag and TAFI Ag levels were significantly increased in patients with hypothyroidism, whereas FV, FVIII, vWF, protein C and protein S activities, and TFPI Ag levels were significantly decreased. We did not find any significant correlation between serum thyroid hormones and the hemostatic parameters that we measured. In conclusion, we found some important differences in the hemostatic parameters between the patients with hypothyroidism and healthy controls. Increased FVII, TM, and TAFI and decreased FV, FVIII, vWF, protein C, protein S, and TFPI in these patients represent a potential hypercoagulable and hypofibrinolytic state, possible endothelial dysfunction, which might augment the risk for atherosclerotic and atherothrombotic complications. Thus, disturbances of the hemostatic system may contribute to the excess mortality due to cardiovascular disease seen in patients with hypothyroidism.

The effect of hormone replacement treatment on thrombin-activatable fibrinolysis inhibitor activity levels in patients with Hashimoto thyroiditis

BACKGROUND

Hypothyroid patients have increased risk of cardiovascular diseases, and several mechanisms have been considered responsible in these patients. Although, a few studies demonstrated fibrinolytic system changes in hypothyroid patients, there is no study demonstrating TAFI activity in hypothyroid Hashimoto's thyroiditis patients. The aim of this study was to evaluate TAFI activity status and the effect of L thyroxin hormone replacement treatment on fibrinolytic system in this patient group.

METHODS

Thirty patients with hypothyroid Hashimoto thyroiditis (all were female and the mean age was 44.3+/-14.6 years, ranging between 17-68 years) were enrolled to study. Their TSH levels were high (27.2+/-5.2 mU/L) and Free T3 and Free T4 hormone levels were below than normal. In this study, euthyroid 20 healthy volunteers (mean age 32.5+/-4.9 years, range 26-42 years) were adopted. L-thyroxin treatment before and after TAFI activity levels were measured in patients.

RESULTS

In the control group, TAFI activity levels were 9.6+/-0.4 microg/mL. In patients with L-thyroxin before and after treatment there were high levels of TAFI activity value of 14.2+/-0.9 and 12.9+/-0.8 microg/mL, respectively. In the patient group, after L-thyroxin treatment TAFI activity levels were decreased but they were not statistically significant (p=0.187). When compared to the control group, high levels of TAFI activity were observed in the patient group (p<0.0001).

CONCLUSION

Our data demonstrated that in Hashimoto thyroiditis, patients have high levels of TAFI activity compared to controls. A high level of TAFI activity suggests fibrinolytic deficit or thrombotic tendency in hypothyroid patients and this deficit is persistent after L-thyroxine replacement.

The clinical significance of subclinical thyroid dysfunction

Subclinical thyroid disease (SCTD) is defined as serum free T(4) and free T(3) levels within their respective reference ranges in the presence of abnormal serum TSH levels. SCTD is being diagnosed more frequently in clinical practice in young and middle-aged people as well as in the elderly. However, the clinical significance of subclinical thyroid dysfunction is much debated. Subclinical hyper- and hypothyroidism can have repercussions on the cardiovascular system and bone, as well as on other organs and systems. However, the treatment and management of SCTD and population screening are controversial despite the potential risk of progression to overt disease, and there is no consensus on the thyroid hormone and thyrotropin cutoff values at which treatment should be contemplated. Opinions differ regarding tissue effects, symptoms, signs, and cardiovascular risk. Here, we critically review the data on the prevalence and progression of SCTD, its tissue effects, and its prognostic implications. We also examine the mechanisms underlying tissue alterations in SCTD and the effects of replacement therapy on progression and tissue parameters. Lastly, we address the issue of the need to treat slight thyroid hormone deficiency or excess in relation to the patient's age.

Thrombin activatable fibrinolysis inhibitor antigen levels are inversely correlated with plasminogen activator inhibitor-1 antigen levels in hyperthyroid patients

Both increased and decreased fibrinolytic activity have been reported in patients with hyperthyroidism. Elevated levels of plasma plasminogen activator inhibitor-1 (PAI-1) antigen have been found in hyperthyroid patients. Thrombin activatable fibrinolysis inhibitor (TAFI) is a novel plasma protein, which inhibits fibrinolysis through removal of C-terminal lysines from partially degraded fibrin. Previously, we showed that plasma TAFI antigen levels were increased in patients with overt and subclinical hypothyroidism. The aim of this study is to investigate plasma levels of TAFI and PAI-1 antigens in hyperthyroid patients. PAI-1 and TAFI antigen levels were measured in the plasma of 29 patients with hyperthyroidism (14 overt hyperthyroid and 15 subclinical hyperthyroid), and 26 healthy individuals. Although there were increased levels of PAI-1 antigen in hyperthyroid patients, plasma TAFI antigen levels were significantly lower compared to controls (80.79 ng/ml vs. 32.42 ng/ml, p = 0.000 for PAI-1; 10.42 microg/ml vs. 12.24 microg/ml, p = 0.009 for TAFI). Elevated PAI-1 antigen levels were positively correlated with free thyroid hormones, although TAFI antigen levels were in negative correlation with free thyroxine. Furthermore, an inverse correlation between PAI-1 and TAFI antigen levels was found. Our study demonstrated that TAFI antigen levels were decreased in patients with hyperthyroidism. Inverse correlation with PAI-1 suggests that the decrease in TAFI antigen levels may be due to activation of TAFI pathway. Further studies evaluating the underlying mechanisms of low TAFI antigen levels in hyperthyroidism should be undertaken.