Thrombophilia laboratory findings: Difference between revisions
Jump to navigation
Jump to search
mNo edit summary |
|||
| Line 133: | Line 133: | ||
| Factor X disorders | | Factor X disorders | ||
|} | |} | ||
*Protein C deficiency: Diagnostic testing for protein C deficiency is performed using functional assays including clotting assays, enzyme-linked immunosorbent assays (ELISA) and chromogenic tests to determine levels of protein C activity. Mutational analysis of the PROC gene is also available. | |||
==References== | ==References== | ||
Revision as of 08:00, 14 February 2021
|
Thrombophilia Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Thrombophilia laboratory findings On the Web |
|
American Roentgen Ray Society Images of Thrombophilia laboratory findings |
|
Risk calculators and risk factors for Thrombophilia laboratory findings |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Asiri Ediriwickrema, M.D., M.H.S. [2]
Overview
Laboratory findings consistent with the diagnosis of inherited thrombophilias vary based on the etiology of the thrombus.[1]
Laboratory Findings
Variability in thrombophilia testing
- Warfarin decreases protein C and protein S levels.
- Heparin decreases antithrombin activity and lead to false positive results for lupus anticoagulant.
- Direct acting oral anticoagulants can interfere with evaluation for lupus anticoagulant, antithrombin activity, protein C, and S levels.
- Acute thrombosis decreases antithrombin, protein C, and protein S levels.
- Pregnancy, cirrhosis, nephrotic syndrome, chemotherapies (l-asparaginase), anticoagulants, disseminated intravascular coagulation, and systemic illness can alter coagulation factor levels.
Timing
- Given the variability discussed above, timing is important to accurately evaluate for certain thrombophilic states.[2][3]
- Acute thrombosis can affect levels of coagulation factors, therefore, testing should be delayed for approximately six months.
- Anticoagulation can affect certain tests, and should be completed approximately four weeks following completion of anticoagulation.
- Avoid testing during 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 genetic tests.
Type of tests
Tests for thrombophilia are categorized according to their priority, as summarized below.
- High priority testing should be conducted if thrombophilia screening conditions are met.
- Intermediate and low priority testing should be completed in the appropriate clinical context.
| Priority | Timing | Test | Associated Diagnosis |
|---|---|---|---|
| High | Complete blood count | General | |
| Coagulation studies: INR, prothrombin time, partial thromboplastin time | General | ||
| Factor V Leiden mutation studies | Factor V Leiden | ||
| Prothrombin 20210 gene mutation | Prothrombin G20210A | ||
| Lupus anticoagulant | Antiphospholipid syndrome | ||
| Anticardiolipin antibodies | Antiphospholipid syndrome | ||
| Delay 6 months | Functional assay for antithrombin (antithrombin-heparin co-factor assay) | Antithrombin deficiency | |
| Delay 6 months | Protein C functional assay (preferred over plasma protein levels) | Protein C deficiency | |
| Delay 6 months | Free protein S immunoassay | Protein S deficiency | |
| Intermediate | Factor VIII level (use c-reactive protein as control) | Factor VIII disorders | |
| Flow cytometry | Paroxysmal nocturnal hemoglobinuria | ||
| Peripheral blood smear, JAK2 mutation studies | Myeloproliferative disorders | ||
| Homocysteine level | Hyperhomocysteinemia | ||
| Vitamin B12 level | Hyperhomocysteinemia | ||
| Low | Thrombin time | General/Fibrinogen disorders | |
| Fibrinogen level | Fibrinogen disorders | ||
| Reptilase time | General/Fibrinogen disorders | ||
| Plasminogen level | Plasminogen disorders | ||
| Factor IX activity | Factor IX disorders | ||
| Factor X activity | Factor X disorders |
- Protein C deficiency: Diagnostic testing for protein C deficiency is performed using functional assays including clotting assays, enzyme-linked immunosorbent assays (ELISA) and chromogenic tests to determine levels of protein C activity. Mutational analysis of the PROC gene is also available.
References
- ↑ Seligsohn U, Lubetsky A (2001). "Genetic susceptibility to venous thrombosis". N Engl J Med. 344 (16): 1222–31. doi:10.1056/NEJM200104193441607. PMID 11309638.
- ↑ Cohoon KP, Heit JA (2014). "Inherited and secondary thrombophilia". Circulation. 129 (2): 254–7. doi:10.1161/CIRCULATIONAHA.113.001943. PMC 3979345. PMID 24421360.
- ↑ Stevens SM, Woller SC, Bauer KA, Kasthuri R, Cushman M, Streiff M; et al. (2016). "Guidance for the evaluation and treatment of hereditary and acquired thrombophilia". J Thromb Thrombolysis. 41 (1): 154–64. doi:10.1007/s11239-015-1316-1. PMC 4715840. PMID 26780744.