Hypercoagulable States
| Disorder | Mechanism
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| Antiphospholipid syndrome | There are circulating antibodies that bind plasma proteins with an affinity for phospholipid surfaces, and this can cause thrombosis and in women stillbirth. This syndrome is most often acquired in adulthood, either from an underlying disease or as an idiopathic condition. The two subsets of this syndrome, as defined by laboratory testing, are: lupus anticoagulant (which may or may not be seen with SLE), and anti-cardiolipin antibody
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| Factor V Leiden mutation | This is the most common inherited form of hypercoagulability. The mutation, which leads to activated protein C resistance, is present in 5% of Caucasians but is rare in persons of African and Asian ancestry. Heterozygotes have a mild risk for thrombosis, but the rare homozygotes have a marked risk. A point mutation leads to impaired inactivation of factor V by activated protein C. Recurrent venous thrombosis can occur, starting even in young persons, and in women stillbirth.
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| Elevated factor VIII | This condition is as common as factor V Leiden mutation. There may be genetic and environmental factors causing it. Oral contraceptive use increases factor VIII levels. The result is deep venous thrombosis.
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| Malignant neoplasms | Neoplastic cells may elaborate a factor, such as a thromboplastin-like substance, that can increase the risk for thrombosis. This is one form of paraneoplastic syndrome, with the name Trousseau's syndrome. There can be venous (more likely) or arterial thrombosis.
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| Protein C, Protein S, antithrombin III deficiencies | These conditions are autosomal dominant and lead to recurrent venous thrombosis, even starting in young persons. Thrombosis is often spontaneous, without other precipitating events. They can be detected by laboratory testing for the respective coagulation factor
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| Sticky platelet syndrome | This is an autosomal dominant disorder that can lead to both arterial and venous thrombosis. Stillbirth may occur in women. Stress is a precipitating event.
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| Homocystinemia | Persons with elevated plasma homocysteine levels not only have increased problems with atherosclerosis, but also arterial and venous thrombosis. Stillbirth may occur in women.
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| Prothrombin mutation | The prothrombin G20210A mutation increases the level and activity of prothrombin that mildly increases the risk for arterial and venous thrombosis. The mutation occurs more often in persons of southern European ancestry.
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| Plasminogen abnormalities | Plasminogen, which has an anticoagulant effect, can be deficient. The features resemble protein C or S deficiency. Also, tissue plasminogen activator can be deficient. Plasminogen activator inhibitor can be increased.
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| Congenital dysfibrinogenemia | This rare autosomal dominant disorder may cause either thrombosis or hemorrhage.
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