High Thyroxine Levels and Risk for Venous Thrombosis

Hyperthyroidism is associated with a hypercoagulable state. Conversely, hypothyroidism is associated with reduced levels of von Willebrand factor and increased risk for bleeding. To investigate the relation between hyperthyroidism and risk for venous thrombosis, researchers in the Netherlands measured thyroid-hormone and thyroid-antibody levels in 190 patients with a first deep venous thrombosis (DVT) and 379 sex-matched controls.

The mean level of free thyroxine was significantly higher among DVT patients than among controls (16.2 pmol/L vs. 15.4 pmol/L; P<0.01), as was the mean T₃ level (1.90 nmol/L vs. 1.79 nmol/L; P<0.01). The higher the thyroxine level, the greater the risk for DVT, such that a level above the reference threshold (>24 p…