The alteration of coagulation in patients with thyroid dysfunction

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

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

Cerebral Venous Thrombosis during Thyrotoxicosis: Case Report and Literature Update

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

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.

Pathophysiology and management of intracranial arterial stenosis around the circle of Willis associated with hyperthyroidism: case reports and literature review

Cases of moyamoya disease or intracranial arterial stenosis around the circle of Willis (M/IAS) associated with hyperthyroidism have been reported. However, most of these previous reports were of the ischemic form of M/IAS and primary hyperthyroidism. To the best of our knowledge, no studies have documented therapy for M/IAS associated with hyperthyroidism. We discuss four previously unreported cases, including those involving the intracerebral hemorrhage form and thyroid-stimulating hormone (TSH) secretion from a pituitary adenoma (secondary hyperthyroidism). We analyzed data from 52 previously reported cases, including the 4 cases presented here, and discuss M/IAS associated with hyperthyroidism, treatment options, pathophysiology, the ischemic and hemorrhagic forms, secondary hyperthyroidism, and the relevant literature. Hyperthyroidism results in thyrotoxicosis and the stimulation of the superior cervical ganglion by TSH antibodies and f-T3/f-T4. Consequently, hypercoagulability and stenosis of the cerebral artery can occur. There are many reports of ischemic M/IAS associated with hyperthyroidism. A conservative approach to treatment is important in such cases; for example, antithyroid therapy should be the first choice to treat ischemic M/IAS. There have been only a limited number of reports on hemorrhagic M/IAS. We presume that hemorrhagic M/IAS tears the weakened vasculature in a manner similar to that of normal M/IAS (with no complicating hyperthyroidism). The authors also reported M/IAS associated with secondary hyperthyroidism due to pituitary thyroid secreting hormone secreting adenoma.