Thrombophilia
From Wikipedia, the free encyclopedia
| Thrombophilia Classification and external resources |
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| ICD-9 | 286.9 |
|---|---|
| OMIM | 188050 |
| DiseasesDB | 29080 |
| MeSH | D019851 |
Thrombophilia is the propensity to develop thrombosis (blood clots) due to an abnormality in the system of coagulation.[1] Hereditary defects in one or more of the clotting factors can cause the formation of potentially dangerous blood clots (thrombosis). Approximately 5-8% of the U.S. population has one of these clotting disorders collectively called thrombophilia, a propensity for blood clotting in which a genetic defect can be identified that often results in thrombosis.
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[edit] Associated conditions
More than 60,000 Americans die each year from venous thromboembolism; in addition, nearly half of patients with deep vein clots experience long-term health consequences that adversely affect their quality of life.
Thrombophilia is highly predictive of vein thrombosis.[2]
[edit] Indications
Searching for a coagulation abnormality is not normally undertaken in patients in whom thrombosis has an obvious other cause. For example, if the thrombosis is due to immobilisation after recent orthopedic surgery, it is unlikely that an underlying cause is found. However, as knowledge about this condition grows, well-informed hematologists are testing more broadly.
Conversely, although thrombosis itself may occur in any person, repeated (two or more) unprovoked episodes of thrombosis and unusual sites and types of thrombosis (e.g. Budd-Chiari syndrome) may point towards a coagulation disorder.
Increasingly, recurrent miscarriage is seen as an indication for thrombophilia screening. [3]
[edit] Classification
Thrombophilia can be classified in various forms.
- The most common classification is by the nature of the thrombosis: arterial, venous or combined.
- Crowther & Kelton (2003) propose to classify the abnormality by the molecular deficiency, type I being the (severe) deficiencies of inhibitors, and type II being the less severe elevation of coagulation factors.[4]
- Acquired vs. congenital
[edit] Types
Common types:
- Factor V, Leiden type (5% of the population are heterozygous for FVL).
- Prothrombin mutation (G20210A, 5'UTR).
- High homocysteine levels due to MTHFR mutation or vitamin deficiency (vitamins B6, B12 and folic acid).
- Antiphospholipid antibodies
- Renal disease (renal loss of antithrombin)
- Paraneoplastic hypercoagulability, usually secondary to large adenocarcinomas of the digestive tract or the lung. When clots appear in superficial veins, it is called Trousseau's sign.
Rare forms:
- Plasminogen and fibrinolysis disorders.
- Paroxysmal nocturnal hemoglobinuria
- Protein C deficiency.
- Protein S deficiency.
- Antithrombin III deficiency.
[edit] Testing
Tests for thrombophilia include prothrombin time and INR, partial thromboplastin time, thrombin time, fibrinogen levels, antiphospholipid antibody levels (IgG- and IgM-anticardiolipin, dilute Russell viper venom time and lupus anticoagulant), protein C, protein S and antithrombin (both levels and activity), activated protein C resistance (APC resistance), factor V Leiden and prothrombin mutation. There is substantial variation in the tests ordered,[5] and many laboratories add on various other tests, depending on local policy and guidelines.
[edit] References
- ^ Heit JA (2007). "Thrombophilia: common questions on laboratory assessment and management". Hematology Am Soc Hematol Educ Program 2007: 127–35. doi:. PMID 18024620.
- ^ Spiezia L, Tormene D, Pesavento R, Salmaso L, Simioni P, Prandoni P (March 2008). "Thrombophilia as a predictor of persistent residual vein thrombosis". Haematologica 93 (3): 479–80. doi:. PMID 18310547.
- ^ Dawood, F., Farquharson, R., Quenby, S. Recurrent miscarriage. Current Obstetrics & Gynaecology, 2004; 14:247-253.
- ^ Crowther MA, Kelton JG (2003). "Congenital thrombophilic states associated with venous thrombosis: a qualitative overview and proposed classification system". Ann. Intern. Med. 138 (2): 128-34. PMID 12529095.
- ^ Jackson BR, Holmes K, Phansalkar A, Rodgers GM (2008). "Testing for hereditary thrombophilia: a retrospective analysis of testing referred to a national laboratory". BMC Clin Pathol 8: 3. doi:. PMID 18384680. PMC:2324095.
