Thrombophilia laboratory findings: Difference between revisions
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==Overview== | ==Overview== | ||
==Laboratory testing== | |||
===Indications for screening=== | |||
Routine screening is not indicated in those individuals with an obvious acquired cause. For example, if the thrombosis is due to immobilisation after recent [[orthopedic surgery]], it is unlikely that an underlying cause is found. Comprehensive testing in any patient should include complete assessment of risk factors and its effect on long-term therapy. Some of the indications of further testing may include<ref name="pmid19289024">{{cite journal |author=Foy P, Moll S |title=Thrombophilia: 2009 update |journal=Curr Treat Options Cardiovasc Med |volume=11 |issue=2 |pages=114–28 |year=2009 |month=April |pmid=19289024 |doi= |url=}}</ref><ref name="pmid11309638">{{cite journal |author=Seligsohn U, Lubetsky A |title=Genetic susceptibility to venous thrombosis |journal=N. Engl. J. Med. |volume=344 |issue=16 |pages=1222–31 |year=2001 |month=April |pmid=11309638 |doi=10.1056/NEJM200104193441607 |url=}}</ref>: | |||
* Unexplained venous thromboembolism at an age of less than 50 years | |||
* Recurrent spontaneous thrombosis | |||
* Unusual sites like portal, splenic, mesenteric, hepatic or renal veins | |||
* Family history in first-degree relatives | |||
* Recurrent pregnancy losses<ref>Dawood, F., Farquharson, R., Quenby, S.''Recurrent miscarriage.'' Current Obstetrics & Gynaecology, 2004; 14:247-253.</ref> | |||
* Recurrence of venous thromboembolism while adequately anticoagulated | |||
* Warfarin-induced skin necrosis | |||
* Unexplained arterial thromboembolism in a younger patient without significant arteriosclerosis risk factors and no cardioembolic source | |||
===Timing=== | |||
The timing of tests is very important as it influences the levels of various thrombogenic factors in the body. | |||
* Testing at the time of acute venous thrombosis is not indicated or during ongoing anti-coagulation. | |||
* Best time to test is 4 weeks after completion of anticoagulation. | |||
* Avoid intercurrent severe illness | |||
* Pregnancy, oral contraceptives, hormone replacement therapy and cancer chemotherapy may also affect some tests. | |||
* Factor V Leiden and Prothrombin mutation can be done in patients on anticoagulants and even in acute phase, as these are PCR tests. However, other tests can be done only at a later stage to rule out two disorders. | |||
===Type of tests=== | |||
Tests for thrombophilia are categorized according to their priority, as discussed below: | |||
'''1. General tests:''' These include [[prothrombin time]], INR, and [[partial thromboplastin time]]. | |||
'''2. High priority tests:''' | |||
* Activated protein C resistance | |||
* Factor V Leiden (Homozygosity or heterozygosity) | |||
* Prothrombin gene mutation (G20210A) | |||
* Homocysteine levels | |||
* Factor VIII | |||
* Lupus anticoagulant | |||
'''3. Intermediate priority''' | |||
* Protein C activity | |||
* Protein S activity | |||
* Antithrombin activity | |||
* Anticardiolipin antibodies | |||
'''4. Low priority''' | |||
* Thrombin time | |||
* Fibrinogen levels | |||
* Factor IX activity | |||
* Factor X activity | |||
* [[MTHR]] gene | |||
* '''High priority and intermediate priority tests''' should be performed in those with an unprovoked thrombotic event and have a recurrent event, cerebral-or visceral thrombosis, stillbirth, three or more unexplained spontaneous abortions, family history of venous thrombosis, or are younger than 45 years. | |||
* '''High priority tests''' only should be conducted in those who have a first unprovoked event, age > 45 years, event provoked by pregnancy/puerperium/use of oral contraceptives or hormone-replacement therapy, proximal-vein thrombosis, pulmonary embolism, or both provoked by surgery, trauma, or immobilization. | |||
* It is recommended that all these patients be treated with anticoagulation for at least 6 months, unless contraindicated. | |||
==References== | ==References== | ||
{{reflist|2}} | {{reflist|2}} | ||
Revision as of 13:24, 21 September 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Laboratory testing
Indications for screening
Routine screening is not indicated in those individuals with an obvious acquired cause. For example, if the thrombosis is due to immobilisation after recent orthopedic surgery, it is unlikely that an underlying cause is found. Comprehensive testing in any patient should include complete assessment of risk factors and its effect on long-term therapy. Some of the indications of further testing may include[1][2]:
- Unexplained venous thromboembolism at an age of less than 50 years
- Recurrent spontaneous thrombosis
- Unusual sites like portal, splenic, mesenteric, hepatic or renal veins
- Family history in first-degree relatives
- Recurrent pregnancy losses[3]
- Recurrence of venous thromboembolism while adequately anticoagulated
- Warfarin-induced skin necrosis
- Unexplained arterial thromboembolism in a younger patient without significant arteriosclerosis risk factors and no cardioembolic source
Timing
The timing of tests is very important as it influences the levels of various thrombogenic factors in the body.
- Testing at the time of acute venous thrombosis is not indicated or during ongoing anti-coagulation.
- Best time to test is 4 weeks after completion of anticoagulation.
- Avoid intercurrent severe illness
- Pregnancy, oral contraceptives, hormone replacement therapy and cancer chemotherapy may also affect some tests.
- Factor V Leiden and Prothrombin mutation can be done in patients on anticoagulants and even in acute phase, as these are PCR tests. However, other tests can be done only at a later stage to rule out two disorders.
Type of tests
Tests for thrombophilia are categorized according to their priority, as discussed below:
1. General tests: These include prothrombin time, INR, and partial thromboplastin time.
2. High priority tests:
- Activated protein C resistance
- Factor V Leiden (Homozygosity or heterozygosity)
- Prothrombin gene mutation (G20210A)
- Homocysteine levels
- Factor VIII
- Lupus anticoagulant
3. Intermediate priority
- Protein C activity
- Protein S activity
- Antithrombin activity
- Anticardiolipin antibodies
4. Low priority
- Thrombin time
- Fibrinogen levels
- Factor IX activity
- Factor X activity
- MTHR gene
- High priority and intermediate priority tests should be performed in those with an unprovoked thrombotic event and have a recurrent event, cerebral-or visceral thrombosis, stillbirth, three or more unexplained spontaneous abortions, family history of venous thrombosis, or are younger than 45 years.
- High priority tests only should be conducted in those who have a first unprovoked event, age > 45 years, event provoked by pregnancy/puerperium/use of oral contraceptives or hormone-replacement therapy, proximal-vein thrombosis, pulmonary embolism, or both provoked by surgery, trauma, or immobilization.
- It is recommended that all these patients be treated with anticoagulation for at least 6 months, unless contraindicated.
References
- ↑ Foy P, Moll S (2009). "Thrombophilia: 2009 update". Curr Treat Options Cardiovasc Med. 11 (2): 114–28. PMID 19289024. Unknown parameter
|month=ignored (help) - ↑ Seligsohn U, Lubetsky A (2001). "Genetic susceptibility to venous thrombosis". N. Engl. J. Med. 344 (16): 1222–31. doi:10.1056/NEJM200104193441607. PMID 11309638. Unknown parameter
|month=ignored (help) - ↑ Dawood, F., Farquharson, R., Quenby, S.Recurrent miscarriage. Current Obstetrics & Gynaecology, 2004; 14:247-253.