Factor V, Functional

Test Code

Quest Code

CPT Codes

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

Minimum Volume
0.5 mL

Platelet-poor plasma: 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/mcL). Freeze immediately and ship on dry ice.

Transport Container
Transport tube

Transport Temperature


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

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

Photometric Clot Detection

Setup Schedule
Set up: Mon-Fri; Report available: 1-3 days

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

Reference Range
65-150 % normal

Clinical Significance

This test measures coagulation factor V activity and may be used to help determine the cause of a prolonged prothrombin time (PT) or activated partial thromboplastin time (aPTT).

Coagulation factor V plays an essential role in hemostasis by promoting thrombin generation at the activated platelet surface. Deficiency of factor V leads to a rare bleeding disorder and can be congenital or acquired. Congenital factor V deficiency, also known as parahemophilia or Owren's disease, has an incidence of 1 per one million [1] and is caused by pathogenic variants of the F5 gene, which encodes factor V. Acquired factor V deficiency can be caused by liver disease, consumptive coagulopathies, disseminated intravascular coagulation, or inhibitors (autoantibodies or alloantibodies) that interfere with factor V activity. Inhibitors to factor V may be induced by chemical agents, drugs, or surgical procedures using bovine thrombin [1].

Factor activity assays, including factor V activity assay, are usually indicated in patients with bleeding symptoms and prolonged PT and aPTT [1].

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

1. Tabibian S, et al. Semin Thromb Hemost. 2019;45(5):523-543.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

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.