Common Conditions That Increase Your Risk


Cancerous cells may produce clotting substances such as tissue factor-containing microparticles that lead to an increased risk of blood clots. Cancer may also lead to blockages in veins and an increase in inflammatory chemicals, which also increase the potential for clots.


Immobilization due to prolonged travel (more than eight hours) or surgical or medical conditions can lead to pooling of blood in the veins of the legs. This, in turn, can cause clot formation.


Surgical interventions and sometimes the conditions that make surgery necessary may lead to an increase in chemicals involved in swelling, blood pooling in the veins, and prevention of clot breakdown, all of which promote clot formation.


Inflammatory disorders such as Crohn’s disease, ulcerative colitis, and infections increase inflammatory mediators, monocyte procoagulants, and C4-binding protein, thereby decreasing free protein S. These conditions may increase the likelihood of developing a blood clot. Large blood clots, or clots in unusual sites, have been reported in inflammatory bowel disease, including clots of the inferior vena cava, carotid, and mesenteric and portal veins.


Myeloproliferative disorders are blood diseases in which patients experience constant increases in some or all of the blood cells, such as platelets, red blood cells, and white blood cells. Increases in red blood cells and platelets prevent the blood from flowing smoothly and increase the risk of clot formation. A leading cause of death in people with myeloproliferative disorders is blood clots. In fact, clotting episodes may occur before the diagnosis of myeloproliferative disorders.


Nephrotic syndrome is a kidney disorder that causes the body to release too much protein in the urine. Nephrotic syndrome usually is caused by damage to the small blood vessels in the kidneys that filter waste and excess water from the blood. When these blood vessels are damaged, protein can leak out of the blood and lead to swelling all over the body. The kidney damage can lead to a decrease of free protein S and an increase in platelet clumping. All of these associated changes may contribute to the formation of blood clots.