Factor IX Activity, Clotting

*Take to processing ASAP

352

LAB308
 

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

0.5 mL

Centrifuge light blue-top tube for 15 minutes at approximately 1500 g within 60 minutes 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. Plasma must be free of platelets (<10,000/uL). Freeze immediately and ship on dry ice.

Transport tube

Frozen 

Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 14 days

Hemolysis • Received thawed

Tues, thurs, sat

3-6 days

Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: Decrease; Heparin (UFH or LMWH): no effect to inhibitor pattern; Dabigatran or Argatroban (Thrombin Inhibitors): no effect to inhibitor pattern; Rivaroxaban or Apixaban (Factor Xa Inhibitors): no effect to inhibitor pattern.

This test is useful to evaluate a prolonged aPTT. Deficiency of Factor IX can be seen with congenital deficiency (Hemophilia B, X-linked disorder) which affects approximately 1 in 25,000 males. As a vitamin K-dependent clotting factor, decreased levels are also observed with vitamin K antagonists (eg. warfarin therapy) and vitamin K deficiency. Deficiencies may be seen with liver disease, disseminated intravascular coagulation (DIC) and in other consumptive coagulopathies.

Anticoagulant interference: Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: decrease; Heparin (UFH or LMWH): no effect to inhibitor pattern; Dabigatran or Argatroban (Thrombin Inhibitors): no effect to inhibitor pattern; Rivaroxaban, Apixaban, Edoxaban (Factor Xa Inhibitors): no effect to inhibitor pattern. Other limitations: Lupus anticoagulant may cause falsely low to inhibitor pattern. Factor specific inhibitors (autoantibodies or in response to replacement therapies) may cause falsely low or inhibitor patterns.