Thrombosis

A blood clot a.k.a. as thrombus is the result of a reactions involving various proteins, their activators, and inhibitors. The process of blood clotting also involves the blood vessel wall and cellular components of blood (particularly platelets). Clotlysis (fibrinolysis) occurs via a complex series of reactions as well as a variety of tissue components. Thrombosis of a vein is a clot made up of red blood cells, white blood cells and platelets. The clot sticks to the lining of the vein and may partially or totally block the blood. Thrombosis is the basis of a number of disorders. Clots can develop anywhere in the the body, and can involve the organs.

If clotting occurs in the surface veins, it is usually not dangerous and often heals on its own. If both the surface and deep veins are involved, it may be dangerous. Heart attacks and strokes are very often due to thrombosis. The morbidity and mortality associated with clot formation is staggering. There are an estimated 5 to 20 million cases of venous thrombosis in the United States each year. Approximately 40% of the patients with deep vein thrombosis suffer pulmonary embolus which is fatal in 30% of cases. Nearly 50% of patients with deep vein thrombosis suffer sequelae lasting many years, requiring millions of dollars to treat.

Age is a risk factor in thrombosis and clotting commonly occurs in older adults. Blood clots in people younger than 40 are generally due to genetic abnormalities. Some of the inherited risk factors are abnormalities of protein C, protein S, antithrombin, and resistance to activated protein C. Clinical situations which may increase the risk of thrombosis are surgery, pregnancy, hormonal therapy, and prolonged bed rest. Each factor probably has a different risk potential for thrombosis. Once a patient reaches a certain threshold, a clot develops. Many factors remain unknown and the interaction between factors has not been clearly defined.