Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (409 page)

•   Factor V Leiden mutation (if APCR is abnormal): genetic assay

•   Protein C antigen (if functional test is low)

•   Protein S antigen (total and free) (if functional test is low)

•   AT antigen (if functional test is low), except in DIC, heparin therapy, or liver disease: Immunologic assays are rarely necessary

   
Third-tier tests.

•   Thrombin time and fibrinogen for dysfibrinogenemia

•   Factor VIII coagulant

   Other selected clotting factors (fibrinogen, factors VII, IX, vWF) to assess marked elevations—their usefulness is not well documented. Fibrinogen may also be investigated for dysfibrinogenemia.

•   Homocysteine (may be of value for congenital arterial thrombophilia as well)

B.   Arterial thrombophilia
^§§§

   Lipid profile

   Lipoprotein a

   Homocysteine

II.     
Suspected acquired hypercoagulability

   First-tier tests:

   Lupus anticoagulant

   Anticardiolipin and anti-β2 glycoprotein 1 antibodies (IgG and IgM)

   Antinuclear antibodies (ANA)

   DIC (recommended DIC panel: FDP, Latex
D
-dimer, antithrombin)

   Heparin-induced thrombocytopenia (HIT) must be ruled out

   DVT/PE: an ELISA-sensitive, quantitative assay for
D
-dimers to be used in relation with a probability algorithm