Thyroid dysfunction and VTE

The association between the haemostatic system and thyroid conditions was seen back in 1913 when an episode of cerebral vein thrombosis was reported in a patient with thyrotoxicosis (excessive circulating thyroid hormone). Since then, there has been ongoing research to determine what would be the link between thyroid dysfunction and VTE.

Low levels of thyroid hormone production are called hypothyroidism, which has shown to lead to reduced levels of the coagulation protein, von Willebrand factor (VWF); and this can increase the incidence of acquired von Willebrand syndrome which elevates the risk of bleeding. Hypothyroidism is also associated with cholesterol and the risk of cardiovascular disease.

Hyperthyroidism (also known as thyrotoxicosis) is an increase in circulating thyroid hormones, and with this comes raised levels of fibrinogen, factor VIII and VWF which may lead to symptomatic VTE. This thyroid dysfunction has also been associated with arterial thrombosis and atrial fibrillation.

One study’s suggested mechanism involved with increased risk of VTE among patients with hyperthyroidism is resistance to thyroid hormones due to a defective thyroid receptor. A faulty receptor could be caused by a gene mutation. Another research study hypothesised that elevated levels of thyroid hormone may act directly on endothelial cells leading to a hypercoagulable condition over a long period of time causing VTE.

Hyperthyroidism is shown to cause atrial fibrillation with a prevalence of 16%–60% prevalence. It has also been found that patients with atrial fibrillation and hyperthyroidism have a higher increased risk of thromboembolism.

Some of the common symptoms associated with hyperthyroidism include:

  • Heart palpitations.
  • Feelings of anxiety and nervousness.
  • Inability to handle heat; sweating.
  • Increased appetite.
  • Weight loss.
  • Breathlessness.
  • Eye problems.
  • Difficulty sleeping.
  • Changes to your skin and hair - thinning skin; brittle hair.
  • In some cases, the thyroid gland can become enlarged (goitre); which is a large lump or swelling at the base of the front of the neck.

Hyperthyroidism can be difficult to diagnose due the diverse range of symptoms. However it is recommended to see your GP if some of these symptoms, like weight loss, sweating or rapid heartbeat occur without explanation.

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