Factor XII Activity, Clotting

Test Code

362

CPT Codes
85280

Preferred Specimen

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

Minimum Volume

0.5 mL

Instructions

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 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 ship on dry ice.

Transport Temperature

Frozen

Specimen Stability

Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 28 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Hemolysis

Methodology
Photometric Clot Detection

Setup Schedule

Monday-Friday Morning Report available: Next Day

Limitations

Expected impact by therapeutic levels (potential interference depends upon drug concentration): Warfarin: no effect; 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.

Reference Range

50-150 % normal

Clinical Significance

The Factor XII Activity clotting assay provides a quantitative level of Factor XII activity. Deficiency of Factor XII is not associated with a bleeding or thrombotic risk. In the absence of a lupus anticoagulant, Factor XII deficiency should be suspected when an isolated prolonged aPTT occurs in a non-bleeding patient. Direct thrombin or factor Xa inhibitors may yield falsely low results and/or inhibitor pattern with testing. If not clinically contraindicated, avoid for approximately 2-3 days before testing. Vitamin K antagonists (eg. warfarin therapy) have no effect on levels.

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.