Endothelial function in patients with hyperthyroidism before and after treatment with propranolol and thiamazol

A Retrospective Case-Control Study Examining the Association of Thyroid-Stimulating Hormone Suppression and Vascular Wall Inflammation on [18F]FDG-PET/CT

Background: This retrospective case-control study aimed to investigate the effects of thyroid-stimulating hormone (TSH) suppression on vascular wall inflammation, assessed by [18F]-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT). Vascular [18F]FDG-uptake is highly correlated with arterial inflammation, which represents a major risk factor for atherosclerotic plaques. Methods: Forty patients with differentiated thyroid cancer underwent [18F]FDG-PET/CTs under TSH suppression therapy following surgical removal of the thyroid and subsequent radioiodine ablation. The [18F]FDG-uptake was measured in the carotid arteries, aortic arch, and the ascending, descending, and abdominal aorta. All measurements in the PET scans were normalized to body weight and corrected for blood pool activity in the superior vena cava, creating target-to-background ratios (TBRs). Twenty-five patients with euthyroid hormone status were used as a control group. In addition, to evaluate long-term changes, the follow-up PET/CTs of 24 thyroid carcinoma patients under continued TSH suppression therapy were analyzed. Results: In patients with TSH suppression, significantly higher arterial [18F]FDG-uptake (p < 0.001) was observed in the ascending aorta, aortic arch, abdominal aorta, carotid artery, and for all arterial vessels combined (mean TBRmax ± standard deviation [SD]: 1.8 ± 0.4, 1.8 ± 0.3, 1.9 ± 0.4, 1.4 ± 0.3, 1.7 ± 0.2, respectively) compared with the euthyroid control group (TBRmax ± SD: 1.4 ± 0.2, 1.4 ± 0.2, 1.4 ± 0.2, 1.1 ± 0.2, 1.3 ± 0.1, respectively). In the subgroup of patients who received an additional follow-up scan after a mean duration of 1.9 ± 1.1 years of continued TSH suppression therapy, no significant changes in arterial [18F]FDG-uptake were found in the five arterial sites when both scans were compared over time (p > 0.05). Conclusions: Our study suggests that patients under TSH suppression may experience a significant increase in vascular [18F]FDG-uptake, a marker of arterial inflammation, and, therefore, might be at higher risk for cardiovascular disease. Interestingly, the duration of TSH suppression was not significantly associated with vascular [18F]FDG-uptake in our study, indicating that the observed increase in arterial inflammation may not be influenced by the duration of TSH suppression.

Association Between Thyrotoxicosis and Cerebral Venous Thrombosis

Thyrotoxicosis appears to be a predisposing factor for cerebral venous thrombosis (CVT), which is a rare but important cause of stroke in young adults. The presentation of CVT is highly variable, ranging from a history of headaches (in the majority of cases) to deep coma, with the latter requiring invasive neurosurgical decompression. Although the long-term outcomes of CVT are favorable, multicenter cohort studies have shown that death may occur in up to 4% of cases in the acute phase and 8-10% of cases in the long term. It has been argued that the substantial decrease in mortality in patients with CVT that has been observed during the past few decades may be the result of an increased awareness of CVT among clinicians. Given that thyrotoxicosis is a risk factor for CVT, clinicians (and endocrinologists) should be alert to the possibility of CVT in patients with thyroid disease in order to prevent it whenever possible or treat it promptly. In this review, we provide an updated overview of the characteristics of patients with thyrotoxicosis who presented with CVT, the underlying mechanisms, and a few tips for clinicians.

Endothelial dysfunction and cardiovascular diseases: The role of human induced pluripotent stem cells and tissue engineering

Cardiovascular disease (CVD) remains to be the leading cause of death globally today and therefore the need for the development of novel therapies has become increasingly important in the cardiovascular field. The mechanism(s) behind the pathophysiology of CVD have been laboriously investigated in both stem cell and bioengineering laboratories. Scientific breakthroughs have paved the way to better mimic cell types of interest in recent years, with the ability to generate any cell type from reprogrammed human pluripotent stem cells. Mimicking the native extracellular matrix using both organic and inorganic biomaterials has allowed full organs to be recapitulated in vitro. In this paper, we will review techniques from both stem cell biology and bioengineering which have been fruitfully combined and have fueled advances in the cardiovascular disease field. We will provide a brief introduction to CVD, reviewing some of the recent studies as related to the role of endothelial cells and endothelial cell dysfunction. Recent advances and the techniques widely used in both bioengineering and stem cell biology will be discussed, providing a broad overview of the collaboration between these two fields and their overall impact on tissue engineering in the cardiovascular devices and implications for treatment of cardiovascular disease.

The association between hypothyroidism and perinatal outcomes in patients with polycystic ovary syndrome

PURPOSE

To compare pregnancy, delivery, and neonatal outcomes in patients with polycystic ovary syndrome (PCOS) with and without concomitant hypothyroidism.

METHODS

A retrospective population-based cohort study including all women with an ICD-9 diagnosis of PCOS in the US between 2004 and 2014, who delivered in the third trimester or had a maternal death. We compared women with a concomitant diagnosis of hypothyroidism to those without. Women with hyperthyroidism were excluded. Pregnancy, delivery, and neonatal outcomes were compared between the two groups.

RESULTS

Overall, 14,882 women met inclusion criteria. Among them, 1882 (12.65%) had a concomitant diagnosis of hypothyroidism, and 13,000 (87.35%) did not. Women with concomitant hypothyroidism, compared to those without, were characterized by increased maternal age (25.5% ≥ 35 years vs. 18%, p < 0.001, respectively), and had a higher rate of multiple gestations (7.1% vs. 5.7%, p = 0.023). Interestingly, pregnancy, delivery and neonatal outcomes were comparable between the groups, except for a higher rate of small-for-gestational-age (SGA) neonates in the group with hypothyroidism (4.1% vs. 3.2%, p = 0.033) (Tables 2 and 3). In a multivariate logistic regression adjusting for potential confounders, hypothyroidism was no longer found to be associated with SGA (adjusted odds ratio [aOR] 1.32, 95% confidence interval [CI] 0.99-1.75, p = 0.057), but was found to increase the odds for preeclampsia (aOR 1.30, 95% CI 1.06-1.59, p = 0.012).

CONCLUSIONS

In patients with PCOS, concomitant hypothyroidism significantly increases the risk for preeclampsia. Unexpectedly, other pregnancy complications commonly increased by hypothyroidism were not increased in women with PCOS, likely due to the inherent elevated baseline pregnancy risks of PCOS.

Fluctuations in Thyroid Hormone Levels During Initial Treatment for Differentiated Thyroid Carcinoma are Associated with Changes in Hemostasis: A Prospective Cohort Study

Background: During treatment for differentiated thyroid carcinoma (DTC), patients go from euthyroidism to severe hypothyroidism to subclinical hyperthyroidism induced by thyroid hormone suppression therapy (THST). Severe hypothyroidism may induce a tendency toward bleeding, whereas hyperthyroidism is thrombogenic. Therefore, treatment for DTC may increase the risk of bleeding during thyroid hormone withdrawal, and thrombosis during THST. This study aims to provide prospective analysis of changes in the hemostatic system from euthyroidism to hypothyroidism, and during THST, in patients treated for DTC. Methods: This is a secondary study in a larger Dutch prospective cohort. Consecutive samples were obtained from 20 patients (18 female [90%]; median age 48 [interquartile range 35.8-56.5] years) throughout their treatment for DTC during euthyroidism (n = 5), severe hypothyroidism (n = 20), and THST (n = 20). We measured selected hemostatic proteins and C-reactive protein (CRP), performed functional tests of hemostasis (a thrombin generation test and a plasma-based clot lysis test), and assessed markers of in vivo activation of hemostasis (thrombin-antithrombin complexes, plasmin-antiplasmin [PAP] complexes, and D-dimer levels). Results: During hypothyroidism, the majority of measured parameters did not change. During THST, plasma levels of nearly all measured hemostatic proteins were higher than during hypothyroidism. Additionally, CRP significantly increased from 1.3 (0.5-3.3) to 3.2 (1.3-5.1) mg/L during THST (p < 0.01). Ex vivo thrombin generation increased from 626.0 (477.0-836.3) to 876.0 (699.0-1052.0) nM × min (p = 0.02), and ex vivo clot lysis time increased from 60.6 (55.6-67.4) to 76.0 (69.7-95.0) minutes during THST (p < 0.01). PAP levels reduced from 266.5 (211.8-312.0) to 192.0 (161.0-230.0) μg/L during THST (p < 0.01); other markers of in vivo activation of coagulation remained unaffected. Conclusions: During THST-induced hyperthyroidism, a shift toward a more hypercoagulable and hypofibrinolytic state occurred. However, in vivo activation of hemostasis did not increase. The rise in CRP levels suggests the presence of a low-grade inflammation in patients during THST. Both a hypercoagulable and hypofibrinolytic state and a low-grade inflammation are associated with an increased risk of cardiovascular diseases (CVD). Therefore, the subtle changes found during THST could potentially play a role in the pathogenesis of CVD as observed in DTC patients. Clinical Trial Registration: This study is part of a larger clinical trial registered at the Netherlands Trial Register (NTR ID 7228).

Genome-wide association study of hyperthyroidism based on electronic medical record from Taiwan

Excess thyroid hormones have complex metabolic effects, particularly hyperthyroidism, and are associated with various cardiovascular risk factors. Previous candidate gene studies have indicated that genetic variants may contribute to this variable response. Electronic medical record (EMR) biobanks containing clinical and genomic data on large numbers of individuals have great potential to inform the disease comorbidity development. In this study, we combined electronic medical record (EMR) -derived phenotypes and genotype information to conduct a genome-wide analysis of hyperthyroidism in a 35,009-patient cohort in Taiwan. Diagnostic codes were used to identify 2,767 patients with hyperthyroidism. Our genome-wide association study (GWAS) identified 44 novel genomic risk markers in 10 loci on chromosomes 2, 6, and 14 (P < 5 × 10–14), including CTLA4, HCP5, HLA-B, POU5F1, CCHCR1, HLA-DRA, HLA-DRB9, TSHR, RPL17P3, and CEP128. We further conducted a comorbidity analysis of our results, and the data revealed a strong correlation between hyperthyroidism patients with thyroid storm and stroke. In this study, we demonstrated application of the PheWAS using large EMR biobanks to inform the comorbidity development in hyperthyroidism patients. Our data suggest significant common genetic risk factors in patients with hyperthyroidism. Additionally, our results show that sex, body mass index (BMI), and thyroid storm are associated with an increased risk of stroke in subjects with hyperthyroidism.

Impact of radioiodine treatment on acute phase proteins in hyperthyroid cats

OBJECTIVES

The aim of this study was to investigate the impact of radioiodine treatment (RIT) on the acute phase proteins (APPs) serum amyloid A (SAA), alpha-1-acid glycoprotein (AGP) and haptoglobin (Hp) in hyperthyroid cats.

METHODS

Between June 2013 and November 2014, 33 hyperthyroid cats without clinical or laboratory signs of inflammatory or neoplastic disease and a body weight >2.5 kg were enrolled. Immediately before, and 12, 36, 72 h and 6 days after RIT, serum samples were obtained for determination of APP concentrations.

RESULTS

Both SAA and AGP concentrations changed significantly after RIT. The concentration of AGP increased gradually after treatment with a maximum concentration at the end of the study period (median baseline 398 μg/ml; median 6 days post-RIT 562 μg/ml [P = 0.001]). A relevant >two-fold increase in AGP was seen in 8/33 (24%) cats. SAA concentration increased significantly within 12 h (baseline 9.2 μg/ml; 12 h post-RIT 22.5 μg/ml [P = 0.012]). In 7/33 (21%) cats, a clinically relevant >10-fold increase in SAA was observed. Hp concentration showed no significant change (P = 0.12).

CONCLUSIONS AND RELEVANCE

RIT induced a mild, mainly not clinically relevant acute phase reaction (APR). AGP and SAA were useful APPs to determine RIT-induced APR.

Association between maternal thyroid function and risk of gestational hypertension and pre-eclampsia: a systematic review and individual-participant data meta-analysis

BACKGROUND

Adequate maternal thyroid function is important for an uncomplicated pregnancy. Although multiple observational studies have evaluated the association between thyroid dysfunction and hypertensive disorders of pregnancy, the methods and definitions of abnormalities in thyroid function tests were heterogeneous, and the results were conflicting. We aimed to examine the association between abnormalities in thyroid function tests and risk of gestational hypertension and pre-eclampsia.

METHODS

In this systematic review and meta-analysis of individual-participant data, we searched MEDLINE (Ovid), Embase, Scopus, and the Cochrane Database of Systematic Reviews from date of inception to Dec 27, 2019, for prospective cohort studies with data on maternal concentrations of thyroid-stimulating hormone (TSH), free thyroxine (FT₄), thyroid peroxidase (TPO) antibodies, individually or in combination, as well as on gestational hypertension, pre-eclampsia, or both. We issued open invitations to study authors to participate in the Consortium on Thyroid and Pregnancy and to share the individual-participant data. We excluded participants who had pre-existing thyroid disease or multifetal pregnancy, or were taking medications that affect thyroid function. The primary outcomes were documented gestational hypertension and pre-eclampsia. Individual-participant data were analysed using logistic mixed-effects regression models adjusting for maternal age, BMI, smoking, parity, ethnicity, and gestational age at blood sampling. The study protocol was registered with PROSPERO, CRD42019128585.

FINDINGS

We identified 1539 published studies, of which 33 cohorts met the inclusion criteria and 19 cohorts were included after the authors agreed to participate. Our study population comprised 46 528 pregnant women, of whom 39 826 (85·6%) women had sufficient data (TSH and FT₄ concentrations and TPO antibody status) to be classified according to their thyroid function status. Of these women, 1275 (3·2%) had subclinical hypothyroidism, 933 (2·3%) had isolated hypothyroxinaemia, 619 (1·6%) had subclinical hyperthyroidism, and 337 (0·8%) had overt hyperthyroidism. Compared with euthyroidism, subclinical hypothyroidism was associated with a higher risk of pre-eclampsia (2·1% vs 3·6%; OR 1·53 [95% CI 1·09-2·15]). Subclinical hyperthyroidism, isolated hypothyroxinaemia, or TPO antibody positivity were not associated with gestational hypertension or pre-eclampsia. In continuous analyses, both a higher and a lower TSH concentration were associated with a higher risk of pre-eclampsia (p=0·0001). FT₄ concentrations were not associated with the outcomes measured.

INTERPRETATION

Compared with euthyroidism, subclinical hypothyroidism during pregnancy was associated with a higher risk of pre-eclampsia. There was a U-shaped association of TSH with pre-eclampsia. These results quantify the risks of gestational hypertension or pre-eclampsia in women with thyroid function test abnormalities, adding to the total body of evidence on the risk of adverse maternal and fetal outcomes of thyroid dysfunction during pregnancy. These findings have potential implications for defining the optimal treatment target in women treated with levothyroxine during pregnancy, which needs to be assessed in future interventional studies.

FUNDING

Arkansas Biosciences Institute and Netherlands Organization for Scientific Research.

The application of new concepts of the assessment of the thyroid state to pregnant women

Recently proposed concepts regarding the nature and assessment of the thyroid state have provided a model more consistent with empiric evidence. It now appears likely that there are no such entities as thyroid set points and individual euthyroidism. Rather than there being discrete thyroid states, peripheral organ parameters are associated with thyroid function in a continuous manner. Thyroid hormone levels and, in particular, levels of free thyroxine now appear to be superior to thyrotropin levels as indicators of the thyroid state. Complicating the assessment of the correlations of the thyroid state with pregnancy outcomes are the contribution of the placenta to maternal thyroid function, fetal thyroid development, the multiple potential pathways to any particular outcome, the likely presence of small critical periods of time, the differing genetics of fetal and maternal tissues, and the unreliability of thyroid hormone assays. Nevertheless, there is no apparent reason for there to be a change in pregnancy to the basic principles of thyroid hormone action. The relationships between mild abnormalities of the thyroid state and pregnancy outcomes and the value of treating such mild abnormalities remain uncertain and controversial. The evidence suggests that further investigation of these clinical questions might better be based on thyroid hormone, particularly free thyroxine, levels. In the investigation of borderline low thyroid states, the categories of subclinical hypothyroidism and isolated hypothyroxinemia might both be abandoned with attention being directed to low free thyroxine levels regardless of the thyroid-stimulating hormone (TSH) levels. For these changes to occur, there would ideally be improvements in the assays for free thyroxine in pregnancy. The evidence suggests that, just as in the non-pregnant situation, pregnancy guidelines based on thyrotropin levels may need revision.

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.

Risk of Thromboembolism in Non-Valvular Atrial Fibrillation With or Without Clinical Hyperthyroidism

Background:

Patients with hyperthyroidism have higher risk of atrial fibrillation (AF). However, the risk of thromboembolic event in patients with hyperthyroidism-related AF is controversial.

Objectives:

The aim of the study was to examine the risk of thromboembolic events in AF patients with/without hyperthyroidism.

Methods:

The national retrospective cohort study enrolled AF population was derived from the Taiwan National Health Insurance Research Database. The comparison between the AF patients with clinical hyperthyroidism (HT-AF group) and AF patients without hyperthyroidism (non-thyroid AF group) was made in a propensity score matched cohort and in a real-world setting, of which, the CHA₂DS₂-VASc level was treated as a stratum variable. The outcomes were ischemic stroke and systemic thromboembolism.

Results:

There were 3,880 patients in HT AF group and 178,711 in non-thyroid AF group. After propensity score analysis, the incidence of thromboembolism event and ischemic stroke were lower in HT AF patients than non-thyroid AF patients (1.6 versus 2.2 events per 100 person-years; HR, 0.73; 95% CI, 0.64–0.82 and 1.4 versus 1.8 events per 100 person-years; HR, 0.74; 95% CI, 0.64–0.84, respectively) in the 4.3 ± 3.2 year follow up period. The differences persistently existed in those receiving anticoagulants or not. In AF patients without anticoagulants, the incidence densities of ischemic stroke/systemic thromboembolism were significantly lower in HT AF group than those in non-thyroid AF group at CHA₂DS₂-VASc scores ≤ 4 (HR, 0.41; 95% CI, 0.35–0.48, p < 0.001), while the differences disappeared in case of score ≥ 5 (HR, 0.80; 95% CI, 0.63–1.02, p = 0.071).

Conclusion:

Patients with HT AF had lower incidence of thromboembolic events as compared to non-thyroid AF patients. The threshold of CHA₂DS₂-VASc score for anticoagulation in AF patients with clinical hyperthyroidism should be further evaluated.

Highlights

Antithyroid Drug Treatment in Graves' Disease

Graves' disease is associated with thyrotropin (TSH) receptor stimulating antibody, for which there is no therapeutic agent. This disease is currently treated through inhibition of thyroid hormone synthesis or destruction of the thyroid gland. Recurrence after antithyroid drug (ATD) treatment is common. Recent studies have shown that the longer is the duration of use of ATD, the higher is the remission rate. Considering the relationship between clinical outcomes and iodine intake, recurrence of Graves' disease is more common in iodine-deficient areas than in iodine-sufficient areas. Iodine restriction in an iodine-excessive area does not improve the effectiveness of ATD or increase remission rates. Recently, Danish and Korean nationwide studies noted significantly higher prevalence of birth defects in newborns exposed to ATD during the first trimester compared to that of those who did not have such exposure. The prevalence of birth defects was lowest when propylthiouracil (PTU) was used and decreased by only 0.15% when methimazole was changed to PTU in the first trimester. Therefore, it is best not to use ATD in the first trimester or to change to PTU before pregnancy.

The possible role of the seaweed Ulva fasciata on ameliorating hyperthyroidism-associated heart inflammations in a rat model

Cardiovascular diseases are key complications primarily associated with hyperthyroidism disorders. The present study sought to ameliorate hyperthyroidism-mediated cardiovascular inflammations and related oxidative stress paradigms in experimental rats using the broadly distributed green seaweed Ulva fasciata. Forty-eight adult male albino rats were recruited and randomly classified into six groups. Hyperthyroidism was stimulated using L-thyroxine sodium at a dose of 100 μg/kg i.p. for 3 weeks daily. Further, 200 mg/kg b.wt. concentration of the U. fasciata methanolic (U. fasciata-MeOH) extract was the recommended dose and administrated orally to the hyperthyroid rats. The standard commercial drug "propranolol hydrochloride" was also tested at a dose of 10 mg/kg i.p. to compare the findings obtained from the seaweed extract. A combined treatment with the U. fasciata-MeOH extract and propranolol hydrochloride was also assessed. Our results implied that the treatment of hyperthyroid rats with the U. fasciata-MeOH extract significantly reduced serum levels of the thyroid hormones T3 and T4, proinflammatory cytokines (TNF-α, MPO, and CRP), triglycerides and total cholesterol, as well as the cardiac biomarkers CK-MB, LDH, and troponin to thresholds close to those of the standard drug. In addition, levels of high-density lipoprotein cholesterol (HDL-C) and interleukin 10 (IL-10) were significantly upregulated. Hyperthyroid rats only treated with propranolol hydrochloride, or with a combination of the drug and the seaweed extract, conferred the same observations. Histopathological architecture boosted our interesting findings where the myocardium tissues in hyperthyroid rats, administrated the U. fasciata-MeOH extract or/and propranolol hydrochloride, exhibited more or less a normal structure as the control, reflecting the potential cardiovascular recovery exerted by this seaweed extract. In vitro DPPH, ABTS, and FRAP antioxidant assays of the U. fasciata-MeOH extract showed an outstanding ROS-scavenging potential. HPLC analysis of the U. fasciata-MeOH extract unraveled an inestimable valuable array of phenolics (mainly p-coumaric, gallic, ferulic, chlorogenic, and syringic acids) and flavonoids (hesperidin, kaempferol, catechin, quercetin, and rutin). Conclusively, the seaweed U. fasciata is a profitable source of antioxidant polyphenolics characterized by having a pharmaceutical potential against hyperthyroidism-linked cardiovascular inflammations and oxidative stress patterns due to their substantial free radical quenching properties, and also via regulating the signalling pathways of the proinflammatory, lipid profile, and cardiac biomarkers.

Comparison of 24-Hour Electrocardiogram Parameters in Patients with Graves' Disease Before and After Anti-Thyroid Therapy

BACKGROUND

We aimed prospectively to investigate the laboratory and electrocardiographic parameters (heart rate, QRS, QT, QTc, Tpe, Tpe/QTc, and arrhythmia prevalence) in patients with Graves' disease before and after antithyroid therapy.

METHODS

Seventy-one patients (48 female, and 23 male), of age between 18-50 years (mean±SD: 36.48±12.20) with GD were included in the study. Patients were treated with antithyroid therapy (thioamides and/or surgical therapy) to maintain euthyroid status. Patients were examined in terms of electrocardiographic parameters before and after the treatment.

RESULTS

Mean TSH, free thyroxin (fT4), and tri-iodothyrionine (fT3) levels of all patients were 0.005±0.21, 3.27± 1.81, 11.42±7.44, respectively. While 9 patients (group 2) underwent surgical therapy, had suspicious malignant nodule or large goiter, and unresponsiveness to medical treatment; the other patients (n=62, group 1) were treated with medical therapy. Patients with surgical therapy had more increased serum fT4 (p=0.045), anti-thyroglobulin value (p=0.018) and more severe graves orbitopathy (n=0.051) before treatment when compared to a medical therapy group. Baseline Tpe duration and baseline Tpe/QTc ratio and frequency of supraventricular ectopic beats were found to be significantly higher in group 2 when compared to group 1 (p=0.00, p=0.005). Otherwise, the baseline mean heart rate, QRS duration, QTc values of both groups were similar. Although the patients came at their euthyroid status, group 2 patients still suffered from more sustained supraventricular ectopics beats than group 1.

CONCLUSION

Distinct from the medical treatment group, surgical treatment group with euthyroidism for at least 3 months still suffered from an arrhythmia (Tpe, Tpe/QTc, supraventricular and ventricular ectopic beats).

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.

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.

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

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

Study on the relationship between hyperthyroidism and vascular endothelial cell damage

The aim of the research is to explore the relationship between hyperthyroidism, iodine, antithyroid drugs (propylthiouracil) and vascular endothelial injury. In total, 136 SD rats were randomly allocated into the control group, the hyperthyroidism group, the hyperthyroidism propylthiouracil group, the hyperthyroidism low iodine group, the high iodine group, and the endothelial injury group. Rats were raised for 60 days. Afterward, indicators concerning endothelial damage were determined, including the von Willebrand Factor (vWF), thrombomodulin (TM), nitric oxide (NO), endothelin 1 (ET-1), and P-selectin, as well as the plant hemagglutinin sample type oxidized low-density lipoprotein receptor 1 (LOX-1) from the aorta and the number of endothelial progenitor cells (EPCs) in whole blood. The hyperthyroidism group had significantly higher values for vWF, TM, NO, ET-1, and P-selectin in serum and a higher number of EPCs in whole blood compared with the control group, similar to the LOX-1 expression in abdominal aorta. The hyperthyroidism low iodine group had significantly higher values for vWF, ET-1, and P-selectin in serum and a higher number of EPCs in whole blood compared with those of the control group, as was the case for LOX-1 expression in the abdominal aorta. The hyperthyroidism propylthiouracil group had significantly higher values for FT₄ in the serum compared with those in the control group. The electron microscope showed that hyperthyroidism caused a certain degree of endothelial injury to the abdominal aorta in rats. Hyperthyroidism can damage the vascular endothelium and is a high-risk factor for cardio-cerebrovascular disease. Propylthiouracil could be used in the treatment of hyperthyroidism, thus protecting endothelial cells from damage.

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.

Risk of Adverse Obstetric Outcomes and the Abnormal Growth of Offspring in Women with a History of Thyroid Cancer

Background: It is unclear whether a history of thyroid cancer is associated with an increased risk of adverse pregnancy outcomes in subsequent pregnancies. This study aimed to evaluate the risk of adverse obstetric outcomes and the abnormal growth of offspring in women with a history of thyroid cancer. Methods: This retrospective observational study used nationwide data from between 2006 and 2014 to compare pregnancy outcomes of women with a history of thyroid cancer and those with no such history. Cases of thyroid cancer were identified using ICD-10 codes. Results: During the study period, 7232 women with a history of thyroid cancer and 2,269,051 women without a history of thyroid cancer gave birth. The risks of cesarean section, preterm birth, low birth weight, large for gestational age, preeclampsia, placental abruption, placenta previa, and stillbirth were not different between the groups. Women with a history of thyroid cancer had a statistically higher risk of postpartum hemorrhage (odds ratio [OR] = 1.23 [confidence interval (CI) 1.15-1.32], p < 0.05, corrected with the false discovery rate). Additionally, generalized estimating equations analysis showed that there was no difference in the risk of underweight (OR = 1.05 [CI 0.93-1.19]) and obese (OR = 0.94 [CI 0.84-1.05]) offspring assessed over a period of 80 months after adjusting for confounding factors. Conclusions: Women with a history of thyroid cancer have similar pregnancy outcomes and offspring growth to those with no such history.

TSH suppression aggravates arterial inflammation - an 18F-FDG PET study in thyroid carcinoma patients

Purpose

We aimed to investigate the influence of both hypothyroidism and thyroid-stimulating hormone (TSH) suppression on vascular inflammation, as assessed with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT).

Methods

Ten thyroid carcinoma patients underwent an ¹⁸F-FDG PET/CT during post-thyroidectomy hypothyroidism and during thyrotropin (TSH) suppression after ¹³¹I (radioiodine) ablation therapy. We analysed the ¹⁸F-FDG uptake in the carotids, aortic arch, ascending, descending, and abdominal aorta to investigate the effects of thyroid hormone status on arterial inflammation. Target-to-background ratios (TBRs) corrected for blood pool activity were established for all arterial territories. Results were further compared to euthyroid historic control subjects.

Results

In general, there was a trend towards higher vascular TBRs during TSH suppression than during hypothyroidism (TBR_max all vessels = 1.6 and 1.8, respectively, p = 0.058), suggesting a higher degree of arterial inflammation. In concurrence with this, we found increased C-reactive protein (CRP) levels after levothyroxine treatment (CRP = 2.9 mg/l and 4.8 mg/l, p = 0.005). An exploratory comparison with euthyroid controls showed significant higher TBRs during TSH suppression for the carotids, aortic arch, thoracic descending aorta, and when all vascular territories were combined (TBR_maxp = 0.013, p = 0.016, p = 0.030 and p = 0.018 respectively).

Conclusions

Arterial inflammation is increased during TSH suppression. This finding sheds new light on the underlying mechanism of the suspected increased risk of cardiovascular disease in patients with TSH suppression.

Electronic supplementary material

The online version of this article (10.1007/s00259-019-04292-w) contains supplementary material, which is available to authorized users.

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.

Gene expression differences between thyroid carcinoma, thyroid adenoma and normal thyroid tissue

To identify differences in gene expression profiles of infected cells between thyroid carcinoma (C), thyroid adenoma (A) and normal thyroid (N) epithelial cells, differentially expressed genes were identified using three pairwise comparisons with the GEO2R online tool. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were used to classify them at the functional level. The most significant cluster in the N vs. A pairwise comparison had four hub genes: Insulin-like growth factor 2, Von Willebrand factor (VWF), multimerin 1 (MMRN1) and complement factor D (CFD). In N vs. C, the most significant cluster had 19 genes: IGF2, early growth response 2, transcription factor 3, KIT proto‑oncogene receptor tyrosine kinase, SMAD family member 9, MLLT3 super elongation complex subunit, runt related transcription factor 1, CFD, actinin α 1, SWI/SNF related matrix associated actin dependent regulator of chromatin subfamily a member 4, JunD proto‑oncogene AP‑1 transcription factor subunit, serum response factor (SRF), FosB proto‑oncogene, AP‑1 transcription factor subunit, connective tissue growth factor (CTGF), SRC proto‑oncogene, non‑receptor tyrosine kinase, MMRN1, SRY‑box 9, early growth response 3 and ETS variant 4. In A vs. C, the most significant cluster had 14 genes: BCL2-like 1, galectin 3, MCL1 BCL2 family apoptosis regulator, DNA damage inducible transcript 3, BCL2 apoptosis regulator, CTGF, matrix metallopeptidase 7, early growth response 1, kinase insert domain receptor, TIMP metallopeptidase inhibitor 1, apolipoprotein E, VWF, cyclin D1 and placental growth factor. Histological evidence was presented to confirm the makeup of the hubs prior to logistic regression analysis to differentiate benign and malignant neoplasms. The results of the present study may aid in the search for novel potential biomarkers for the differential diagnosis, prognosis and development of drug targets of thyroid neoplasm.

Cerebral venous sinus thrombosis precipitated by Graves' disease

Cerebral venous sinus thrombosis usually occurs in patients with a precipitating condition such as thrombophilic disorders, pregnancy or due to medications, such as oestrogens. Some case reports have reported the co-occurrence of cerebral venous sinus thrombosis in patients with hyperthyroidism. However, the association of cerebral venous sinus thrombosis with hyperthyroidism remains contentious. We present the case of a patient who presented with a clinical picture of cerebral venous sinus thrombosis with no obvious precipitating factor. Further investigations revealed the presence of hyperthyroidism due to Graves' disease, which was thought to be the provocative disorder for cerebral venous sinus thrombosis. We would like to draw the attention of clinicians to a possible causative association between cerebral venous sinus thrombosis and hyperthyroidism.

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.

The effect of hyperthyroidism on procoagulant, anticoagulant and fibrinolytic factors

Several coagulation and fibrinolytic parameters appear to be affected by thyroid hormone excess;however, the net effect on the haemostatic system remains unclear. We aimed to update our previous review and systematically summarise and meta-analyse the data by assessing the effects of thyrotoxicosis on the coagulation and fibrinolytic system in vivo. Data sources included MEDLINE (2006–2012), EMBASE (2006–2012), and reference lists. The sources were combined with our previous search containing studies from 1980–2006. Eligible studies were all observational or experimental studies. Two investigators independently extracted data and rated study quality. Weighted mean proportion and 95% confidence intervals were calculated and pooled using a fixed and a random-effects model. A total of 29 articles consisting of 51 studies were included, as in several articles more than one study was described. We included four intervention (before and after treatment in hyperthyroid patients), five cross-sectional (hyperthyroid subjects and euthyroid controls), and four experimental (before and after use of thyroid hormone in euthyroid subjects) medium/high quality studies for meta-analysis. We found that thyrotoxicosis shifts the haemostatic balance towards a hypercoagulable and hypofibrinolytic state with a rise in factors VIII and IX, fibrinogen, von Willebrand factor, and plasminogen activator inhibitor-1. This was observed in endogenous and exogenous thyrotoxicosis, and in subclinical as well as overt hyperthyroidism. We conclude that both subclinical and overt hyperthyroidism induce a prothrombotic state, which is therefore likely to be a risk factor for venous thrombosis.

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 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.

Changes in Choroidal Perfusion after Orbital Decompression Surgery for Graves' Ophthalmopathy

Purpose:

To assess choroidal perfusion before and after orbital decompression surgery in patients with Graves' ophthalmopathy.

Methods:

In this interventional case series, surgical decompression for optic nerve compromise was performed on four eyes of three patients with Graves' disease. Complete ophthalmic examination including visual acuity, color vision, and intraocular pressure assessment were done pre- and postoperatively. High-speed indocyanine green angiography was performed prior to surgery and was repeated one year after surgery.

Results:

In all three patients, choroidal perfusion defects were noted pre-operatively in the eyes with the compressive optic neuropathy. At 1 year after orbital decompression surgery, the defects improved or completely resolved. Improved visual acuity and color perception, as well as decreased intraocular pressure, were also noted postoperatively.

Conclusion:

Patients with Graves' orbitopathy may have abnormal choroidal perfusion even in the absence of optic neuropathy. Orbital decompression may improve choroidal circulation in these patients.

Evaluation of endothelial function in exogenous subclinical hyperthyroidism and the effect of treatment

BACKGROUND

Subclinical hyperthyroidism (SHy) is a widespread condition in which cardiovascular manifestations are frequently occur, but there is still a debate about the vascular responsiveness in it. Measuring flow-mediated dilation (FMD) and intimae-media thickness (IMT) are used to evaluate endothelial function in these patients.

MATERIALS AND METHODS

Twenty-five patients with a diagnosis of exogenous SHy and 25 full matched healthy subjects were enrolled. At first FMD of brachial artery and IMT of common carotid artery were obtained from all the participants. In the second phase, in the second phase of study, the dosage of levothyroxine was reduced at least 25% of prior dosage, and this was continued until thyroid stimulating hormone became normal range. Measuring FMD and IMT was repeated after this intervention in the case group.

RESULTS

The mean age of case and control groups were 38.48 ± 12.05 and 36.72 ± 11.15 years, respectively. The mean of FMD in healthy people was dramatically higher than the subclinical hyperthyroid patients (P < 0.001) but no statistically significant difference was found for IMT (P = 0.459). After intervention in the case group, FMD was meaningfully increased (P < 0.001) but IMT of common carotid artery was not considerably changed (P = 0.491).

CONCLUSIONS

This study demonstrated that FMD decreased in exogenous subclinical hyperthyroid patients which could be partially restored by treatment. These findings suggest that treatment of subclinical hyperthyroid state could improve endothelial dysfunction and at the end decreased the cardiovascular complications.

Von Willebrand factor and coagulation factor VIII in Moyamoya disease associated with Graves' disease: A case report

The present study reported the case of a Chinese boy who was diagnosed with Moyamoya disease (MMD) associated with Graves' disease (GD). An overactivation of von Willebrand factor (vWF) and coagulation factor VIII (FVIII) was identified in the plasma of the patient. Thiamazole and metoprolol treatment was thus administrated. After 2 months of treatment, the patient's thyroid function returned to normal and the neurological symptoms improved gradually. At the same time, the activities of vWF and FVIII were depressed. During the 20-month follow-up, information regarding the neurological symptoms, cerebrovascular imaging, thyroid function, thyroid autoantibodies and coagulation parameters was collected. High levels of thyroid autoantibodies persisted throughout the follow-up period, while other coagulation parameters remained in the normal range. In conclusion, considering the vital role of vWF and FVIII in vascular diseases, it is hypothesized that these two factors may serve an important role in the occurrence of GD associated with MMD.

Signal peptide-CUB-EGF domain-containing protein 1 (SCUBE1) levels in patients with overt and subclinical hyperthyroidism: effects of treatment

BACKGROUND AND OBJECTIVES

Signal peptide-CUB-EGF domain-containing protein 1 (SCUBE1) has been shown to increase in parallel with platelet activation in acute ischaemic and thrombotic diseases. There has been no study evaluating SCUBE1 levels in patients with overt hyperthyroidism (OHyper) and subclinical hyperthyroidism (SHyper), conditions which are known to show impairment of both endothelial and platelet function. This study sought to evaluate SCUBE1 concentrations in patients with SHyper and OHyper, and assessed the effects of antithyroid drug (ATD) therapy on circulating SCUBE1 levels.

DESIGN AND METHODS

Forty-five untreated patients with OHyper, 20 untreated patients with SHyper and 30 age- and sex-matched healthy controls were prospectively included in the study. Biochemical and hormonal parameters were evaluated in all patients before and after treatment.

RESULTS

Compared with the control subjects, SCUBE1 levels were significantly increased in patients with SHyper and OHyper (P < 0·0001 and P = 0·002, respectively). SCUBE1 levels were not significantly different in patients with OHyper compared with patients with SHyper. There was no significant correlation between serum thyroid hormones and SCUBE1 levels. Plasma SCUBE1 levels decreased significantly in both OHyper and SHyper after ATD treatment (P < 0·05).

CONCLUSIONS

Increased SCUBE1 levels in both SHyper and OHyper patients may reflect increased platelet activation and possible endothelial dysfunction, which might augment the risk for atherosclerotic and atherothrombotic complications. SCUBE1 may be used as a reliable marker of endothelial damage in hyperthyroidism, especially in the subclinical period.

The Hypercoagulable state in Hyperthyroidism is mediated via the Thyroid Hormone β Receptor pathway

OBJECTIVE

Hyperthyroidism is associated with a hypercoagulable state, but the underlying mechanism is unknown. Patients with resistance to thyroid hormone (RTH) due to defective thyroid hormone receptor β (TRβ) exhibit elevated circulating thyroid hormones (TH) with refractoriness to TH action in TRβ-expressing tissues. We tested the hypothesis that the hypercoagulable state in hyperthyroidism is mediated via the TRβ.

DESIGN

We conducted a cross-sectional study from November 2013 to January 2015 in 3 hospitals in the Netherlands and the United Kingdom.

METHODS

Patients with RTH due to defective TRβ (n=18), patients with hyperthyroidism (n=16) and euthyroid subjects (n=18) were included. TH concentrations and markers of coagulation and fibrinolysis were measured. Data are expressed as median [interquartile range].

RESULTS

Free thyroxine (FT4) levels were slightly higher in hyperthyroid patients than in RTH patients (53.9 [30.5-70.0] and 34.9 [28.4-42.2]pmol/l, respectively, P=0.042). Both groups had raised FT4 levels compared to euthyroid subjects (14.0 [13.0-15.8] pmol/l, P≤0.001). Levels of von Willebrand factor (VWF), factor (F) VIII, fibrinogen, and D-dimer were significantly higher in hyperthyroid patients than in RTH patients (VWF 231 [195-296] vs. 111 [82-140]%, FVIII 215 [192-228] vs. 145 [97-158]%, fibrinogen 3.6 [3.0-4.4] vs. 2.8 [2.5-3.2]g/L, D-dimer 0.41 [0.31-0.88] vs. 0.20 [0.17-0.26]mg/L, respectively, P≤0.001), while there were no differences between RTH patients and euthyroid controls.

CONCLUSIONS

Parameters of coagulation and fibrinolysis were elevated in hyperthyroid patients compared to patients with RTH due to defective TRβ, whereas these parameters were not different between euthyroid controls and RTH patients, despite elevated FT4 concentrations in RTH patients. This indicates that the procoagulant effects observed in hyperthyroidism are mediated via the TRβ.

The immediate and late effects of thyroid hormone (triiodothyronine) on murine coagulation gene transcription

Thyroid dysfunction is associated with changes in coagulation. The aim of our study was to gain more insight into the role of thyroid hormone in coagulation control. C57Black/6J mice received a low-iodine diet and drinking water supplemented with perchlorate to suppress endogenous triiodothyronine (T₃) and thyroxine (T₄) production. Under these conditions, the impact of exogenous T₃ on plasma coagulation, and hepatic and vessel-wall-associated coagulation gene transcription was studied in a short- (4 hours) and long-term (14 days) setting. Comparing euthyroid conditions (normal mice), with hypothyroidism (conditions of a shortage of thyroid hormone) and those with replacement by incremental doses of T₃, dosages of 0 and 0.5 μg T₃/mouse/day were selected to study the impact of T₃ on coagulation gene transcription. Under these conditions, a single injection of T₃ injection increased strongly hepatic transcript levels of the well-characterized T₃-responsive genes deiodinase type 1 (Dio1) and Spot14 within 4 hours. This coincided with significantly reduced mRNA levels of Fgg, Serpinc1, Proc, Proz, and Serpin10, and the reduction of the latter three persisted upon daily treatment with T₃ for 14 days. Prolonged T₃ treatment induced a significant down-regulation in factor (F) 2, F9 and F10 transcript levels, while F11 and F12 levels increased. Activity levels in plasma largely paralleled these mRNA changes. Thbd transcript levels in the lung (vessel-wall-associated coagulation) were significantly up-regulated after a single T₃ injection, and persisted upon prolonged T₃ exposure. Two-week T₃ administration also resulted in increased Vwf and Tfpi mRNA levels, whereas Tf levels decreased. These data showed that T₃ has specific effects on coagulation, with Fgg, Serpinc1, Proc, Proz, Serpin10 and Thbd responding rapidly, making these likely direct thyroid hormone receptor targets. F2, F9, F10, F11, F12, Vwf, Tf and Tfpi are late responding genes and probably indirectly modulated by T₃.

Prothrombotic changes due to an increase in thyroid hormone levels

OBJECTIVE

With increasing free thyroxine levels, a gradually rising risk of venous thromboembolism has been described in case-control studies. However, reports on the influence of thyroid hormones on haemostasis, while suggesting a hypercoagulable state in thyrotoxicosis, have often been inconclusive. This study evaluates multiple markers of haemostasis and fibrinolysis in a paired design, making it more sensitive to changes in thyroid hormone levels.

DESIGN

We analysed multiple variables in patients who shifted from severe hypothyroidism to mild hyperthyroidism during thyroid cancer treatment. Those with possible residual disease were excluded.

METHODS

Ninety patients following total thyroidectomy were tested on two occasions: i) before radioiodine remnant ablation and ii) 6 weeks later, on levothyroxine (lT4) suppression treatment, and the results were compared using the Wilcoxon's test for paired data.

RESULTS

During lT4 treatment, significant increases (all P<0.001) in fibrinogen (from median 3.4 to 3.8 g/l), von Willebrand factor (from 85 to 127%), factor VIII (from 111 to 148%) and plasminogen activator inhibitor 1 (from 6.5 to 13.9 μg/l) were observed. In addition, the activation times of platelet adhesion and aggregation stimulated with collagen and epinephrine (EPI)/ADP, i.e. closure times in platelet function analyser (PFA-100), were significantly shortened (P<0.001): for EPI from median 148 to 117 s and for ADP from 95 to 80 s. Changes in other tests were less prominent or insignificant.

CONCLUSIONS

An increase in thyroid hormone levels shifts the haemostatic balance towards a hypercoagulable, hypofibrinolytic state. This may contribute to the increased cardiovascular morbidity and mortality observed even in mild thyrotoxicosis.

Thyroid Function in Pregnancy: What Is Normal?

BACKGROUND

Gestational thyroid dysfunction is common and associated with maternal and child morbidity and mortality. During pregnancy, profound changes in thyroid physiology occur, resulting in different thyroid-stimulating hormone (TSH) and free thyroxine (FT4) reference intervals compared to the nonpregnant state. Therefore, international guidelines recommend calculating trimester- and assay-specific reference intervals per center. If these reference intervals are unavailable, TSH reference intervals of 0.1–2.5 mU/L for the first trimester and 0.2–3.0 mU/L for the second trimester are recommended. In daily practice, most institutions do not calculate institution-specific reference intervals but rely on these fixed reference intervals for the diagnosis and treatment of thyroid disorders during pregnancy. However, the calculated reference intervals for several additional pregnancy cohorts have been published in the last few years and show substantial variation.

CONTENT

We provide a detailed overview of the available studies on thyroid function reference intervals during pregnancy, different factors that contribute to these reference intervals, and the maternal and child complications associated with only minor variations in thyroid function.

SUMMARY

There are large differences in thyroid function reference intervals between different populations of pregnant women. These differences can be explained by variations in assays as well as population-specific factors, such as ethnicity and body mass index. The importance of using correct reference intervals is underlined by the fact that even small subclinical variations in thyroid function have been associated with detrimental pregnancy outcomes, including low birth weight and pregnancy loss. It is therefore crucial that institutions do not rely on fixed universal cutoff concentrations, but calculate their own pregnancy-specific reference intervals.

Maternal early-pregnancy thyroid function is associated with subsequent hypertensive disorders of pregnancy: the generation R study

CONTEXT

Hypertensive disorders during pregnancy are associated with a wide range of maternal and fetal complications, and only a few risk factors are known for the development of these disorders during pregnancy. Conflicting and limited data are available on the relationship between thyroid (dys)function and the risk of hypertensive disorders of pregnancy.

OBJECTIVE

The objective of the investigation was to study the associations between early-pregnancy thyroid dysfunction, thyroid function within the normal range, and the risk of hypertensive disorders.

DESIGN, SETTING, AND PARTICIPANTS

In early pregnancy, serum TSH, free T4 (FT4), and thyroperoxidase antibody (TPOAb) levels were determined in 5153 pregnant women. No interventions were done. The associations of thyroid function with the risk of hypertensive disorders were studied.

MAIN OUTCOME MEASURES

Mean blood pressures and hypertensive disorders, including pregnancy-induced hypertension (n = 209) and preeclampsia (n = 136), were measured.

RESULTS

Hyperthyroid mothers had a higher risk of hypertensive disorders [odds ratio (OR) 3.40 [95% confidence interval (CI) 1.46-7.91], P = .005], which was mainly due to an increased risk of pregnancy-induced hypertension [OR 4.18 (95% CI 1.57-11.1), P = .004]. Hypothyroidism and hypothyroxinemia were not associated with hypertensive disorders. Within the normal range, the high-normal FT4 levels were associated with an increased risk of hypertensive disorders [OR 1.62 (95% CI 1.06-2.47), P = .03], which was mainly due to an increased risk of preeclampsia [OR 2.06 (95% CI 1.04-4.08), P = .04]. The TPOAb status was not associated with hypertensive disorders.

CONCLUSIONS

We show that biochemical hyperthyroidism and also high-normal FT4 levels during early pregnancy are associated with an increased risk of hypertensive disorders. These data demonstrate that these associations are even seen for a mild variation in thyroid function within the normal range.

Unexpected causes of pulmonary hypertension in a previously healthy Thai rural man with right-sided heart failure

Male, 52

Final Diagnosis: Pulmonary hypertension

Symptoms: Diarrhea • dyspnea • jaundice

Medication: —

Clinical Procedure: —

Specialty: Endocrinology and Metabolic

The impact of thyroid autoimmunity on arterial stiffness in postmenopausal patients with fibromyalgia

OBJECTIVE

The exact mechanism of arterial stiffness in fibromyalgia (FM) remains unclear. The present study aimed to evaluate the association between thyroid function and markers of arterial function in postmenopausal FM patients.

METHODS

This study included 163 postmenopausal FM patients without any known cardiovascular diseases and within a normal reference range of thyroid-stimulating hormone (TSH) level. Clinical parameters including the Fibromyalgia Impact Questionnaire (FIQ), the pain visual analogical scale (VAS) and tender point counts were measured. Vascular function was assessed by brachial-ankle pulse wave velocity (baPWV) and flow-mediated dilation (FMD). We evaluated the associations between arterial markers and serum TSH, free thyroxin, as well as serum thyroidperoxidase autoantibody (TPO Ab).

RESULTS

Patients with a high baPWV (≥ 1490 cm/s) showed more positive TPO Ab (65% vs. 10%, P = 0.006) than those with a normal baPWV. Additionally, the baPWV values of patients with positive TPO Ab were significantly different from those with negative TPO Ab. Age, FIQ and TPO Ab were significantly correlated with baPWV and FMD (all P < 0.05). Multiple linear regression analysis revealed that the only significant predictors of baPWV were age, FIQ and the presence of TPO Ab after adjustment for traditional risk factors. A significant association was also found between FMD and positive TPO Ab.

CONCLUSION

Age, functional status and presence of TPO Ab were significantly associated with increased arterial stiffness in postmenopausal FM patients. Given the combined thyroid autoimmunity in FM patients, a re-evaluation of the effects on the vasculature may be necessary.

Thyroid disease and the nervous system

Thyroid disorders are common in the general population and in hospitalized patients. Thyroid disease may present first with neurological complications or else may occur concurrently in patients suffering other neurological disorders, particularly those with an autoimmune etiology. For this reason neurologists will commonly encounter patients with thyroid disease. This chapter provides an overview of the neurological complications and associations of disorders of the thyroid gland. Particular emphasis is placed on conditions such as thyrotoxic periodic paralysis and myxedema coma in which the underlying thyroid disorder may be occult leading to a first, often emergency, presentation to a neurologist. Information about clinical features, diagnosis, pathogenesis, therapy, and prognosis is provided. Emphasis is placed on those aspects most likely to be relevant to the practicing neurologist and the interested reader is directed to references to good, recent review articles for further information.

Hemostatic changes in thyroid diseases

Several studies have reported hemostatic abnormalities, both in terms of bleeding or thrombosis, in patients with various thyroid dysfunctions. The aim of this review is to briefly discuss the relationship between thyroid disorders and hemostasis (i.e. primary hemostasis, coagulation factors and fibrinolytic system). From the analysis of the more recent literature data, it appears evident that most of the coagulation abnormalities associated with thyroid disorders are a consequence of a direct action of thyroid hormones on the synthesis of various hemostatic factors or a derangement of immune function. On the whole, these data suggest that a hypercoagulable state is present in hyperthyroid patients, while patients suffering from moderate hypothyroidism are at increased risk of thrombosis contrasting with the bleeding tendency of those presenting severe hypothyroidism.

Endothelial dysfunction in Graves' disease

PURPOSE

Graves' disease (GD) is an organ-specific autoimmune thyroid disease, characterized by hyperthyroidism due to excessive production of thyroid hormone induced by thyrotropin receptor-specific stimulatory autoantibodies. In this study, we determined serum levels of the soluble forms of ICAM-1, VCAM-1, vWF, IL-6, IL-12, IL-18, fibrinogen and CRP in patients with subclinical (SH) and overt hyperthyroidism (OH) caused by GD to elucidate a possible role of those parameters as markers of endothelium dysfunction (ED).

MATERIAL/METHODS

The study included 96 patients: 52 with GD and 44 euthyroid controls, divided into 3 groups according to their thyroid function tests: SH, OH and controls (CG).

RESULTS

The values of IL-6, IL-12 and IL-18 were significantly higher in GD than in CG patients (p < 0.0001, p < 0.0001; p < 0.00001, respectively). Significant difference of sVCAM-1 values were found in the patients with GD compared to CG (p < 0.0001). Patients with GD had significantly higher levels of PAI-1 (p < 0.00001), vWF (p < 0.0001), fibrinogen (p < 0.0001) in comparison to CG. In patients with OH, we observed statistically higher values of fibrinogen compared to SH group (p < 0.05). There were no significant differences in serum concentration of other study parameters in patients with SH compared to the OH.

CONCLUSIONS

ED occurs during subclinical and overt hyperthyroidism causing decreased fibrinolytic activity, hypercoagulability and increased levels of IL-6, Il-12 and IL-18. These results support the notion that serum cytokines could be used as a marker of GD activity. Results of this study support the opinion that GD might require treatment as early as in the phase of SH.

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

Introduction. The aim of the present study was to compare the levels of circulating markers of endothelial function and low-grade inflammation in patients with subclinical and overt hyperthyroidism (OH) due to Graves disease (GD) and toxic nodular goiter (TNG). Material and Methods. The group studied consisted of 42 patients with GD, 75 patients with TNG, and 39 healthy controls. Results. Circulating markers of endothelial dysfunction were elevated in the patients with both SH and OH, but the concentrations of interleukin-12 (IL-12) (P < 0.05), IL-18 (P < 0.05), fibrinogen (P < 0.01), and von Willebrand factor (vWF) (P < 0.05) were significantly higher in the OH than in the SH group. The highest levels of IL-6, IL-12, IL-18, vWF, sVCAM-1, and fibrinogen were found in the patients with GD, but the differences between the GD, and TNG groups were not significant. In the subjects with OH serum IL-6 was positively associated with FT3 (R = 0.276, P < 0.05), FT4 (R = 0.273, P < 0.05), and thyroid peroxidase antibodies (R = 0.346, P < 0.01) levels. Conclusion. Our results may suggest that both SH and OH may be associated with endothelial dysfunction, which is reflected by decreased fibrinolytic activity, hypercoagulability, and increased levels of IL-6, IL-12, and IL-18 and depends not only on the cause but also on the degree of hyperthyroidism.

Role of surrogate markers of atherosclerosis in clinical and subclinical thyroidism

Background. Data on the relationship between homocysteine, plasminogen activator inhibitor 1, hs-CRP, fibrinogen, and carotid intima media thickness (CA-IMT) is plenty but contradicting and the majority of the studies investigated this issue in only specific thyroidism groups. The aim of this paper was to investigate these relations in patients with subclinical and clinical hypo- and hyperthyroidism. Methods. In this cross-sectional study, 16 patients from each thyroidism group and 20 healthy cases were enrolled. Fibrinogen levels and plasminogen activator inhibitor 1 (PAI-1) activity were assessed. CA-IMT was determined by gray-scale high-resolution color Doppler ultrasound. Results. Serum homocysteine levels were higher in hypothyroidic patients compared to the control (P = 0.003). Fibrinogen levels were higher in patients with subclinical hypothyroidism compared to other groups (P < 0.05). There was no difference between groups regarding PAI-1. Whereas total cholesterol, homocysteine, and LDL were correlated with CAIMT, hs-CRP, PAI-1, and fibrinogen were not. In the clinical hypothyroidism group, the correlation of homocysteine with CA-IMT was derived from the correlation between CA-IMT and homocysteine. Conclusions. Homocysteine and fibrinogen levels are higher in patients with clinical and subclinical hypothyroidism, respectively. Homocysteine level is associated with CA-IMTonly in patients with clinical hypothyroidism.

Alterations in coagulation and fibrinolysis after levothyroxine exposure in healthy volunteers: a controlled randomized crossover study

BACKGROUND

Several hemostatic abnormalities have been reported in hyperthyroidism, but the overall effect of thyroid hormone excess on coagulation and fibrinolysis is unclear.

OBJECTIVE

Our aim was to assess whether the use of supraphysiological doses of levothyroxine leads to coagulation activation and inhibition of fibrinolysis.

PATIENTS AND METHODS

Healthy volunteers were randomized to receive levothyroxine or no medication for 14 days with a washout period of at least 28 days in a crossover design. To study the effects of different degrees of thyroid hormone excess, 16 participants received levothyroxine in a dose of 0.3 mg per day, and 12 received levothyroxine 0.45 or 0.6 mg per day depending on body weight. Several variables of coagulation and fibrinolysis were measured.

RESULTS

Levels of von Willebrand factor activity (VWF:RiCo) and antigen (VWF:Ag), factor (F) VIII, plasminogen activator inhibitor-1 (PAI-1) and clot-lysis time were slightly higher after levothyroxine 0.3 mg per day than after the control situation, but only levels of VWF showed a significant increase from baseline. After levothyroxine 0.45 or 0.6 mg per day, levels of fibrinogen increased by 17%, VWF activity by 24%, VWF antigen by 26%, FVIII by 19%, FIX by 14%, FX by 7%, PAI-1 by 116% and clot-lysis time by 14%, and activated partial thromboplastin time decreased by 3%; all were significant changes compared with the control situation. We did not observe clear evidence of coagulation activation.

CONCLUSIONS

Our data suggest that thyroid hormone excess increases coagulation factor levels and inhibits fibrinolysis in a dose-dependent fashion. This implies an increased risk of venous thrombosis during hyperthyroidism.