Hypercoag Disorders

What is it?
Activation problems
Regulation problems
Breakdown problems
Other factors
Laboratory tests
Treatments
Sources

Laboratory Tests

Although it may be fairly simple to identify that a patient has a clot, identification of the cause may take more time and effort. This is because several of the diagnostic tests that need to be done are affected by an existing or recent blood clot and by any anticoagulant therapy that is given. Often the doctor may have to order a few tests and treat the person’s existing blood clots first. Several weeks or months later, when he is able to take the person off of anticoagulant therapy, the doctor can order other tests to finish his evaluation of the cause of the clotting. Follow-up testing is important in helping to determine a patient’s risk of developing recurrent blood clots.

Initial testing may include: a PT, PTT, CBC, Activated Protein C Resistance (APCR), Factor V Leiden mutation assay (when APCR is abnormal), homocysteine, anticardiolipin antibodies, and a prothrombin 20210 mutation test. If the PTT testing is prolonged, lupus anticoagulant testing may be done later, along with Protein C, Protein S, and Antithrombin (III).

In general, testing may include:

Treatments

Test	Measures	Ordered When/To	Abnormal Results May Indicate
Anticardiolipin antibodies	Presence of antibody	Evaluate recurrent blood clots and/or miscarriages	Antiphospholipid Syndrome
Antithrombin (III) Activity	Activity of Antithrombin	Evaluate recurrent blood clots	Low activity may increase thrombotic risk
Antithrombin (III) 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 Leiden mutation
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 thromboembolism or DIC (disseminated intravascular coagulation)
Dilute Russell Viper Venom Test (dRVVT)	Time to clot test, Evaluates the common pathway of coagulation. Dilute refers to lipid concentration.	Evaluate recurrent blood clots, when PTT is prolonged, looking for a lupus anticoagulant.	When prolonged, suggests lupus anticoagulant may be present, increased risk of thrombosis.
Factor V Leiden mutation	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 or increased use, may be elevated with inflammation, it is an acute phase reactant
Homocysteine	Level in blood	Recurrent blood clots	If elevated, increased cardiac risk and risk of thrombosis
Lupus Anticoagulant (LA)	Panel of tests are used to check for Lupus antibody	Recurrent blood clots and/or miscarriages, prolonged PTT	When PTT or LA sensitive PTT and dRVVT are prolonged it suggests LA, usually confirmed with additional testing; if present, increased risk of thrombosis
LA-sensitive PTT (PTT-LA)	Time to clot test	When Lupus anticoagulant (LA) suspected	If prolonged and ‘corrects’ to normal when phospholipids added, may be due to LA
Methylenetetrahydrofolate Reductase (MTHFR)	Genetic mutation	Homocysteine level is elevated with no clear acquired etiology.	Increased risk for developing elevated homocysteine levels.
Platelet Neutralization Procedure (PNP)	Timed test using either the PTT or the dRVVT, using platelets as a source of phospholipids	Evaluate prolonged PTT 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 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
PT	Time to clot	As part of an initial workup for bleeding or clotting, monitor anticoagulant therapy	Prolonged PT suggests need for additional tests
PTT (Partial Thromboplastin Time)	Time to clot test, Evaluates the intrinsic and common pathways of coagulation cascade	Screens for lupus anticoagulant, monitor anticoagulant therapy	Prolonged PTT suggests need for further tests. May indicate nonspecific inhibitor (such as lupus anticoagulant)