Factor X Activity, Clotting

*Take to processing ASAP

359

LAB758

1 mL frozen platelet-poor plasma collected in 3.2% sodium citrate (light blue-top) tube

0.5 mL

Please submit a separate, frozen vial for each special coagulation assay ordered. Draw blood in a light blue-top tube containing 3.2% sodium citrate, mix gently by inverting 3-4 times. Centrifuge 15 minutes at 1500 g within one hour of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial(s). Freeze immediately and transport on dry ice. 

Transport tube

Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 28 days

Hemolysis • Received thawed

Sun, tues, thurs, fri

2-6 days

Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: decreased, Heparin (UFH or LMWH): no effect (reagent contains heparin neutralizer); Dabigatran or Argatroban (Thrombin Inhibitors): no effect to inhibitor pattern or falsely low; Rivaroxaban or Apixaban (Factor Xa Inhibitors): no effect to inhibitor pattern.

70-150 % normal

The Factor X Activity clotting assay provides a quantitative level of Factor X activity. Factor X is essential for normal hemostasis and deficiencies are associated with increased bleeding risk. As a vitamin K- dependent clotting factor, decreased levels are observed with vitamin K antagonists (eg. warfarin therapy) and vitamin K deficiency. Deficiencies may also occur with hepatic dysfunction, disseminated intravascular coagulopathy (DIC), as a result of inhibitor development, amyloidosis, and with certain malignancies. Congenital Factor X deficiency is extremely rare. Anticoagulant interference: If not clinically contraindicated, avoid warfarin therapy for approximately 2 weeks before testing. Because of the possibility of falsely low levels with direct thrombin inhibitors (eg. Argatroban and Dabigatran) and Factor Xa inhibitors (Rivaroxaban, Apixaban, Edoxaban), these drugs should be avoided, if not clinically contraindicated, for approximately 2-3 days before testing.