von Willebrand Screen (VONWBS)

Test Code

LAB1112

Quest Code

90271

CPT Codes
85240, 85245, 85246, 85730

Includes

Partial Thromboplastin Time, Activated
Factor VIII Activity, Clotting
von Willebrand Factor Antigen
Ristocetin Cofactor

Preferred Specimen

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

Instructions

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.

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

Transport Container

Transport tube

Transport Temperature

Frozen
It is highly recommended to quick-freeze the sample to keep coagulation factors intact by one of the following methods:
1. freeze with liquid nitrogen
2. freeze in mixture of dry ice and methanol
3. freeze in -70 degree C freezer

Specimen Stability

Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 14 days

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

Hemolyzed specimen; received thawed

Methodology
See individual tests

Reference Range

See individual tests

Clinical Significance

This test may be used for initial evaluation of individuals with clinical suspicion of von Willebrand disease (VWD).

von Willebrand factor (VWF) is a blood coagulation protein that has 2 functions: (1) mediating platelet adhesion to the injured endothelium and (2) acting as a protective carrier protein for coagulation factor VIII. Deficiency of VWF causes VWD, the most common inherited bleeding disorder that affects approximately 1 in 1,000 individuals at the primary care level [1]. VWD is classified into type 1 (quantitative deficiency of VWF), type 2 (qualitative deficiency of VWF), and type 3 (total absence of VWF). Different types of VWD are further categorized into subtypes, identification of which is important to inform prognosis and treatment decisions.

Three tests are recommended for initial diagnosis of VWD [2]: VWF antigen, platelet-dependent VWF activity (eg, ristocetin cofactor), and factor VIII activity. Additional tests may be needed to further identify the subtype of VWD.

Test results of acquired von Willebrand syndrome (AVWS) may be similar to those of congenital VWD [1, 2]. However, patients with AVWS do not have a family history of bleeding or a personal life-long history of bleeding. Conditions associated with AVWS include lymphoproliferative disorders, monoclonal gammopathy of undetermined significance, Wilms tumor expressing GPIb, myeloproliferative disorders, aortic stenosis, ventricular assist devices, and hypothyroidism.

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

References
1. James PD, et al. Blood Adv. 2021;5(1):280-300.
2. Higgins RA, et al. Platelets and van Willebrand factor. In: Rifai R, et al, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier Inc; 2022.

Performing Laboratory

Quest Diagnostics Nichols Institute-Chantilly VA

14225 Newbrook Drive

Chantilly, VA 20151-2228

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.