Factor VIII Activity, Clotting, Reflex to Chromogenic

Test Code
70050

CPT Codes
85240

Includes
If Factor VIII Activity, Clotting is ≤20, then Factor VIII Activity, Chromogenic will be performed at an additional charge (CPT code(s): 85240).

Preferred Specimen
2 mL frozen plasma (x2) collected in a 3.2% sodium citrate (light blue-top) tubes

Minimum Volume
1 mL (x2)

Instructions
Platelet-poor plasma: Centrifuge light blue-top tube 15 minutes at approx. 1500 x 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/mcL).
Freeze immediately and ship on dry ice. Do not thaw.

Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII.

Transport Temperature
Frozen

Specimen Stability
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen -20 °C: 14 days
Frozen -70 °C: 1 year

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Received room temperature • Received refrigerated • Received thawed • Hemolysis

Methodology
Photometric Clot Detection

Reflex: Chromogenic Assay

Setup Schedule
Set up: Wed, Sat; Report available: 2-6 days

Reference Range
Factor VIII Activity, Clotting 50-180 % normal
  Factor VIII Activity, Chromogenic 50-160 % normal


Clinical Significance
In the presence of a suspected lupus anticoagulant, the one-stage appt based assay may yield false low FVIII values consistent with "haemophilia" whereas the chromogenic assay avoids lupus anticoagulant interference and yields accurate FVIII results.

Performing Laboratory
Quest Diagnostics Nichols Inst San Juan Capistrano
33608 Ortega Highway
San Juan Capistrano, CA 92690-6130



The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.