Test Directory

The chromogenic factor X activity test can be useful in monitoring patients on vitamin K antagonist therapy where baseline PT is prolonged.

Specimen Type: Citrated Platelet-Poor Plasma

Collection Container: Light Blue Top (Sodium Citrate)

Desired Specimen Volume: 1 mL

1. Collect a sodium citrate tube via venipuncture.
2. Any tube containing an alternative anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes. 

Platelet-Poor Plasma Processing Instructions

1. Perform platelet-poor plasma processing procedure.
2. Transfer 1 mL of platelet-poor plasma to a LabCorp pp transpak frozen purple tube. Freeze immediately.
3. To avoid delays in turnaround time when submitting multiple frozen specimens, please submit separate frozen specimens for each test requested.

Transport to the laboratory frozen. 

• Gross hemolysis
• Clotted specimen

See patient report.

This assay should not be used for monitoring heparin or oral direct factor Xa inhibitors such as rivaroxaban (Xarelto), apixaban (Eliquis) or edoxaban (Savaysa).

• Stuart Factor
• Stuart Prower Factor