Thrombophilia is a cluster of congenital and acquired diseases characterized by an increased tendency to form clots inside the blood vessels (thrombosis). Congenital conditions are inborn and acquired diseases which occur in later in life. Usually thrombophilia results in venous thrombosis, and it can result in thromboembolism. However, there is no specific therapy for thrombophilia. It is managed by treating the underlying disease or with medications that cause thinning of blood.
Mechanism of blood clot formation
Formation of blood clots is necessary to prevent uncontrolled bleeding, especially following trauma. Therefore, blood clotting is controlled by two forces. One force is promoting the clotting of blood and another force is working against it. There is a fine balance between these two forces and blood clotting diseases occur when the balance is shifted to either direction.
Blood clot formation is dependent on three factors. They are factors in the inner blood vessel wall, disturbances of blood flow and alteration in blood composition. Most of the inherited diseases are caused by increased or decreased levels of various proteins in the blood. Acquired diseases are caused by problems in all three aspects of the clotting mechanism. Most of the proteins responsible for blood clot formation are given roman numeral names (e.g. Factor I, Factor II, Factor V).
What are the common causes for thrombophilia?
Congenital or inherited diseases
Mutations can cause problems with Factor V (Factor V Leiden) and Prothrombin. These disorders are relatively common among the general population. they can result in a three to eight-fold increase in risk. However, homozygotes can have a fifty-fold increase in risk.
Increased von Willebrand factor levels can cause a mild form of thrombophilia. It results in a two-fold increase in risk.
Protein S, Protein C and Antithrombin are natural anticoagulants. Deficiency of these proteins causes a severe type of thrombophilia. Usually there is around a ten-fold increase in risk, even in the heterozygote individuals.
Surgery and trauma
Surgery and trauma can cause changes in the composition of the blood and it can damage the inner walls of the blood vessels. The highest risk is seen in orthopedic surgery and in neurosurgery. Incidence of thrombophilia is also high in head trauma, spinal trauma, multiple trauma and fractures of large bones.
Immobilization following surgery and trauma results in an increased risk of blood clotting. In addition, people who travel long distances by air can get venous thrombosis due to prolonged immobilization. The risk is multiplied when the individual has other risk factors of venous thrombosis such as inherited blood clotting diseases, obesity and the use of oral contraceptives.
Patients with certain types of cancer can get thrombophilia. In addition, oral contraceptives can cause thrombophilia when associated with other risk factors. There is a two to three-fold rise in absolute risk for venous thrombosis in women who take oral contraceptives (Br Med J. 2000;321:1190–1195 ). Other common risk factors are hormone replacement therapy, Nephrotic syndrome, pregnancy and anti-phospholipid syndrome.
How is thrombophilia treated?
There is no specific therapy available for thrombophilia. Usually the underlying cause is treated. However, complications of thrombophilia are prevented by drugs that inhibit blood clot formation. They are heparin and warfarin. Heparin is given when there is sudden thrombotic event. Warfarin (Coumadin®) is given to inhibit excess blood clot formation for longer duration.
Since there is a fine balance between blood clot formation and excessive bleeding, these drugs are given by experienced doctors. In addition, the patients need to undertake frequent long term blood tests to determine the blood clotting tendency. The dose of these medications should be adjusted according to the blood tests' results.
Thrombophilia is an increased tendency to form blood clots in the body. It is caused by many congenital and acquired diseases. There is no specific treatment available for thrombophilia and it is managed by long term medications.