Hyperthyroidism is associated with procoagulant changes
in the haemostatic system. At present, it is uncertain
whether this leads to an increased risk of venous and/
or arterial thrombosis. Only a few small studies have
investigated this association but due to methodological
limitations it is not possible to draw any definitive
conclusions at this stage. Here we report two patients with severe venous thromboembolism (VTE) and concomitant hyperthyroidism without any risk factors for VTE. Hereby, we emphasise a possible association as supported by a number of previous studies. In a planned prospective multicentre cohort study we will examine the association between hyperthyroidism and VTE and determine its clinical relevance.