Hypoxia has been linked to augmentation of thrombosis.62–64 Hypoxia-inducible factor-1 (HIF-1) is activated under hypoxic conditions resulting in upregulation of plasminogen activator inhibitor-1 (PAI-1) and TF as well as inhibition of protein S.62–64 Hypoxia inducible factor-2 (HIF-2) is also upregulated and stimulates PAI-1 and inhibits TFPI.65,66 Finally, from another angle obesity influences the risk of a hypercoagulable state. This evidence concerns the gene SERPINE1 and obesity due to melanocortin 4 receptor deficiency.