Surgeon General's Workshop on Deep Vein Thrombosis
Laboratory Testing and the Thrombophilia Workup
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SLIDE 1: Laboratory Testing and the Thrombophilia
Workup
Thomas L. Ortel, M.D., Ph.D.
Duke University Medical Center
8
May 2006
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SLIDE 2: Roles of the Clinical Laboratory
- Useful ancillary data for initial diagnosis (d-dimer).
- Monitoring antithrombotic therapy.
- Evaluation for underlying hypercoagulable state(s).
- Identifies individuals 'at risk' for thrombosis.
- Identifies individuals with an initial thrombosis who are at
higher risk for recurrence.
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SLIDE 3: What laboratory tests are useful in the
acute setting?
- D-dimer (right arrow) supportive data to help rule out venous
thromboembolism.
- Troponins/BNP (right arrow) stratify severity of PE.
- PT, aPTT (right arrow) essential baseline information prior to
starting therapy.
- Hypercoagulable workup generally not useful in the acute
setting.
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SLIDE 4: Who should be considered for thrombophilia
testing?
- Patients with unexplained, or 'idiopathic' thromboembolism.
- Patients with thromboembolism that is unusually extensive, or in an
unusual location (e.g., portal vein thrombosis).
- Patients with a striking family history for venous
thromboembolism.
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SLIDE 5: What tests should be done?
- Activated protein C resistance, with analysis for factor V
Leiden if positive.
- Prothrombin G20210A genotype analysis.
- Antithrombin functional assay.
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- Protein C functional assay.
- Protein S functional assay, with antigenic assays if
indicated.
- Antiphospholipid antibody testing.
- Homocysteine level.
- Factor VIII assay.
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SLIDE 6: Thrombophilic states and race
2 pie charts, 1 for Caucasian and 1 for African-American.
Caucasian
| FVL |
14.5 |
| PT G20210A |
8.2 |
| AT deficiency |
1.9 |
| PC deficiency |
3.7 |
| PS deficiency |
2.3 |
| Elevated FVIII |
25 |
| APLA |
10 |
| |
34.4 |
African-American
| FVL |
14.5 |
| PT G20210A |
8.2 |
| AT deficiency |
1.9 |
| PC deficiency |
3.7 |
| PS deficiency |
2.3 |
| Elevated FVIII |
25 |
| APLA |
10 |
| |
34.4 |
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SLIDE 7: Thrombophilia in the pediatric patient
- Many studies include children with central venous lines and other
acquired disorders.
- Elevated factor VIII and D-dimer is also associated with recurrent
thrombosis
Pie chart.
Age: neonate to 18 yrs
Combined defects
| FVL |
29.2 |
| PT G20210A |
3.7 |
| AT deficiency |
1.7 |
| PC deficiency |
6.6 |
| PS deficiency |
1.3 |
| Elevated Lp(a) |
14.9 |
| Combined defects |
20.9 |
| |
21.7 |
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SLIDE 8: Impact of thrombophilic disorders on
recurrent thromboembolism
Line chart showing Impact of thrombophilic disorders on recurrent
thromboembolism
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SLIDE 9: ACCP Guidelines
2.1.4. For patients with first episode DVT and:
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- Antiphospholipid antibodies;
- 2 or more thrombophilic conditions;
- (right arrow) therapy for 12 months (1C+) or indefinite
(2C).
2.1.5. For patients with first episode DVT and:
-
- Antithrombin, protein C or protein S deficiency;
- Factor V Leiden or prothrombin G20210A;
- Elevated homocysteine or factor VIII levels
- (right arrow) therapy for 6-12 months (1A) or indefinite
(2C).
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SLIDE 10: Cost of thrombophilia testing
| Test |
Approximate Cost* |
| Natural anticoagulants (antithrombin, protein C,
protein S): |
$450-750 |
| Genetic tests (factor V Leiden, prothrombin
G20210A): |
$600 |
| Antiphospholipid antibodies: |
$1000-1500 |
| Other (factor VIII, homocysteine): |
$200 |
| TOTAL: |
$2250-3050 |
* Duke Coagulation Laboratory
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SLIDE 11: What should healthcare providers do with
this information?
- Individuals who test positive for a thrombophilic risk factor require
counseling as to:
- risks of thrombosis to themselves and their family members.
- importance of early recognition of signs and symptoms of venous
thromboembolism.
- risks and benefits of thromboprophylaxis in high-risk
situations.
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SLIDE 12: Should asymptomatic individuals be
screened for thrombophilia?
- Screening of asymptomatic individuals, whether family members of a
patient with thrombosis, or in a situation that places them at increased risk
for thrombosis, is generally not recommended.
- However, in selected situations, knowledge of a specific
thrombophilic state might guide therapeutic decision-making (e.g., decision
concerning HRT usage).
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SLIDE 13: On the other hand, one doesn't even need
the doctor to order the test...
Photo of www.dnadirect.com
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SLIDE 14: Future directions for thrombophilia
testing
- Prospective clinical studies to define:
- Role, if any, of screening asymptomatic family members or
individuals in high-risk situations.
- Impact on optimal therapy for patients with venous thrombosis and
thrombophilia.
- Better education for providers as well as consumers concerning risk
factors, prevention strategies, need for genetic counseling, etc.
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