Cardiolipin antibodies |
Presence of antibody |
Evaluate recurrent blood clots and/or miscarriages |
Antiphospholipid syndrome |
Antithrombin activity |
Activity of antithrombin |
Evaluate recurrent blood clots |
Low activity may increase thrombotic risk |
Antithrombin antigen |
Quantity of antithrombin |
Activity is consistently low |
Decreased production or increased use of factor, may increase thrombotic risk |
APCR (activated protein C resistance) |
Resistance to degradation of activated factor V by APC |
Evaluate recurrent blood clots |
Need to confirm by checking for Factor V mutation (Leiden) |
D-dimer |
Level of a specific type of crosslinked fibrin degradation product |
Evaluate blood clot formation during bleeding and clotting episodes |
If elevated, indicates recent clotting activity. May be due to acute or chronic condition, such as a or (disseminated intravascular coagulation) |
Dilute Russell Viper venom test (dRVVT) |
Time to clot formation test, evaluates the common pathway of coagulation. Dilute refers to lipid concentration. |
Evaluate recurrent blood clots, when APTT is prolonged, looking for a lupus anticoagulant. |
When prolonged, suggests lupus anticoagulant may be present, increased risk of thrombosis. |
Factor V mutation (Leiden) |
Genetic mutation that results in formation of an activated Factor V that resists degradation by APC |
Recurrent blood clots |
Increased risk of thrombosis |
FDP (fibrin degradation products) |
Reflection of clotting and fibrinolytic (clot breakdown) activity |
Evaluate bleeding and clotting |
If increased, indicates recent blood clot formation and breakdown |
Fibrinogen |
Amount of fibrinogen in the circulation. |
Evaluate bleeding and clotting |
If low, may indicate decreased production, increased use, or a functional defect. May be elevated with inflammation as, it is an |
Homocysteine |
Level in blood |
Recurrent blood clots |
If elevated, increased cardiac risk and risk of arterial thrombosis. Also elevated with vitamin B12 or folate deficiency |
Lupus anticoagulant (LA) |
Panel of tests are used to check for lupus antibody |
Recurrent blood clots and/or miscarriages, prolonged APTT |
When APTT or LA sensitive APTT and dRVVT are prolonged it suggests LA, usually confirmed with additional testing; if present, increased risk of arterial and venous thrombosis |
LA-sensitive APTT
(PTT-LA) |
Time to clot formation test |
When lupus anticoagulant (LA) suspected |
If prolonged and ‘corrects’ to normal when phospholipids added, may be due to LA |
Methylene-
tetrahydrofolate reductase (MTHFR) |
Genetic mutation |
Homocysteine level is elevated with no clear acquired aetiology. |
Increased risk for developing elevated homocysteine levels. |
Platelet neutralisation procedure (PNP) |
Timed test using either the APTT or the dRVVT, using platelets as a source of phospholipids |
Evaluate prolonged APTT and recurrent blood clots |
If test corrects to normal with the addition of platelets, may indicate presence of a lupus anticoagulant |
Protein C activity |
Function of Protein C |
Recurrent blood clots |
Protein C helps slow down the coagulation cascade by degrading activated Factors V and VIII. If activity is low, there is an increased risk of thrombosis |
Protein C antigen |
Quantity of protein C |
When protein C activity is low |
If decreased, may be due to an inherited or acquired condition. Increased risk of thrombosis |
Protein S activity |
Function of protein S |
Recurrent blood clots |
Protein S is a cofactor, helps protein C |
Protein S antigen (free and total) |
Quantity of total and free protein S |
When protein S activity low |
Only free protein S is available to assist protein C; total protein S includes free protein S and protein S bound to C4b-binding protein. |
Prothrombin 20210 mutation |
Genetic mutation |
Recurrent blood clots |
Increased risk of thrombosis |
Prothrombin Time (PT) |
Time to clot formation |
As part of an initial workup for bleeding or clotting, monitor anticoagulant therapy |
Prolonged PT is suspicious for a coagulation factor deficiency and suggests the need for additional tests.
Warfarin therapy is monitored with the International Normalised Ratio (INR) which is a test based on the PT. The INR assists medical staff to determine how effective the warfarin is at preventing unwanted clotting. |
APTT (actvated partial thromboplastin time) |
Time to clot formation test, Evaluates the intrinsic and common pathways of coagulation cascade |
Screens for lupus anticoagulant, monitor anticoagulant therapy |
Prolonged APTT suggests need for further tests. May indicate nonspecific inhibitor (such as lupus anticoagulant) |