What are the limitations of lab studies used to rule out an underlying thrombophilia in hereditary and acquired hypercoagulability?

Updated: Jan 05, 2018
  • Author: Paul Schick, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Answer

Tests for hypercoagulability are affected by a number of conditions. Therefore, precautions are important when ordering laboratory studies to rule out an underlying thrombophilia. Limitations on studies that can be performed while patients are undergoing anticoagulation therapy include the following:

  • Testing for antithrombin functional activity should not be done while the patient is on unfractionated heparin or low molecular weight heparin (LMWH)
  • Testing for protein C or S functional activity should not be done while patients are on warfarin, since protein C and protein S are vitamin K–dependent proteins
  • Testing for APC resistance should be deferred when patients are on anticoagulant therapy, since this test is a coagulation assay; however, genetic tests of factor V Leiden can be ordered
  • DRRVT and phospholipid dependence for confirming lupus anticoagulants should not be done while the patient is being anticoagulated, since they are coagulation-based tests, but testing for anticardiolipid antibodies or anti-β(2)glycoprotein 1 antibodies can be performed during anticoagulation
  • Antithrombin, protein S, and protein C levels may be decreased during acute thromboembolism; therefore, both protein assays and functional assays of these proteins could be inaccurate during the acute phase of thromboembolic disease

The tests should be performed in laboratories that specialize in testing for thrombophilia. In addition, the results can be difficult to interpret, so interpretation is best done by a physician with considerable experience with thrombophilias.


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