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Test ID VWFX von Willebrand Factor Activity, Plasma

Reporting Name

von Willebrand Factor Activity, P

Useful For

Diagnosis of von Willebrand disease (VWD) and differentiation of VWD subtypes or differentiation of VWD from hemophilia A

 

Monitoring therapeutic efficacy of treatment with DDAVP (desmopressin) or VWF concentrates in patients with VWD

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
RIST Ristocetin Cofactor, P No No

Testing Algorithm

If von Willebrand factor activity is <55%, then the von Willebrand factor ristocetin cofactor activity assay will be performed at an additional charge.

 

MCF internal patients: von Willebrand factor activity results <55% will not reflex ristocetin cofactor unless ordered as part of von Willebrand profile. Recommend von Willebrand profile testing if not previously performed.

Specimen Type

Plasma Na Cit


Additional Testing Requirements


Tests for F8A / Coagulation Factor VIII Activity Assay, Plasma and VWAG / von Willebrand Factor Antigen, Plasma are recommended in conjunction with von Willebrand activity.



Specimen Required


See Coagulation Studies in Special Instructions.

 

Specimen Type: Platelet-poor plasma

Collection Container/Tube: Light-blue top (citrate)

Submission Container/Tube: Polypropylene vial

Specimen Volume: 2 mL in 2 vials each containing 1 mL

Collection Instructions:

1. Specimen must be drawn prior to factor replacement therapy.

2. Spin down, remove plasma, and spin plasma again.

3. Freeze specimens immediately at ≤-40 degrees C, if possible.

4. Send specimens in the same shipping container.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Na Cit Frozen 14 days

Special Instructions

Reference Values

55-200% 

Normal, full-term newborn infants may have mildly increased levels which reach adult levels by 90 days postnatal. Healthy, premature infants (30-36 weeks gestation) may have increased levels that reach adult levels by 180 days.

Note: Individuals of blood group "O" may have lower plasma von Willebrand factor (VWF) activity than those of other ABO blood groups, such that apparently normal individuals of blood group "O" may have plasma VWF activity as low as 40% to 50%, whereas the lower limit of the reference range for individuals of other blood groups may be 60% to 70%.

Day(s) and Time(s) Performed

Monday through Saturday

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

85397

LOINC Code Information

Test ID Test Order Name Order LOINC Value
VWFX von Willebrand Factor Activity, P 68324-3

 

Result ID Test Result Name Result LOINC Value
VWFX von Willebrand Factor Activity, P 68324-3

Clinical Information

von Willebrand factor (VWF) is a multimeric adhesive glycoprotein that is important for platelet-platelet and platelet-vessel hemostatic interactions. In addition, plasma VWF serves as a carrier protein for coagulation factor VIII, stabilizing its procoagulant activity. VWF circulates in the blood in 2 distinct compartments, plasma VWF and platelet VWF. Plasma VWF mainly reflects VWF synthesis and release from vascular endothelial cells. Platelet VWF (about 10% of the blood VWF) reflects VWF synthesis by bone marrow megakaryocytes with storage primarily in the alpha granules of circulating platelets. VWF antigen measurement assesses the mass of plasma VWF protein, but does not measure platelet VWF protein. The major function of VWF (mediating platelet-platelet or platelet-vessel interaction) is most commonly assessed by measurement of plasma VWF activity.

 

Patients with congenital severe type 3 von Willebrand disease (VWD) have markedly decreased or immeasurably low VWF antigen in the plasma (and in the platelets), and plasma VWF activity is very low or not detectable. Patients with types 2A and 2B variants of VWD (with abnormal plasma VWF function and multimeric structure) may have normal or decreased plasma VWF antigen, but typically have decreased plasma VWF activity, and decreased higher molecular weight VWF multimers in the plasma. Patients with type 2M or type 2N VWD have normal levels of antigen, but either decreased VWF activity not caused by absence of higher molecular weight VWF multimers (type 2M VWD), or decreased factor VIII coagulant activity (type 2N VWD). Patients with type 1 VWD (with decreased but normally functioning plasma VWF) have concordantly decreased plasma VWF antigen and activity.  Patients with acquired von Willebrand syndrome (AVWS) may have either normal or decreased plasma VWF antigen, and decreased VWF activity.

 

Note: This activity assay is most effective when it is combined with measurement of von Willebrand factor: VWF antigen and factor VIII coagulant activity, preferably as a panel of tests with reflexive testing and interpretive reporting [eg, VWPR / von Willebrand Profile]).

Interpretation

von Willebrand factor (VWF) activity is reduced in parallel with VWF antigen in von Willebrand disease (VWD), except in types 2A, 2B, and 2M, and some cases of acquired von Willebrand syndrome (AVWS) in which the VWF activity is disproportionately decreased relative to the level of VWF antigen.

 

The VWF activity may be decreased in congenital VWD or AVWS that may be associated with are variety of disorders including monoclonal gammopathies, lymphoproliferative disorders, autoimmune disorders, hypothyroidism, severe aortic stenosis, left ventricular assist device, and arteriovenous malformation.

 

The VWF activity may be increased in association with pregnancy or estrogen use (including oral contraceptives), acute ("acute-phase reactant") or chronic inflammation, exercise or stress, liver disease, vasculitis, and thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS). Such increases in VWF activity may obscure the laboratory diagnosis of mild VWD. 

Clinical Reference

1. Montgomery RR: Structure and function of von Willebrand factor. In Hemostasis and Thrombosis: Basic Principles and Clinical Practice. Fourth edition. Edited by Colman RW, Hirsh J, Marder VJ, et al. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, pp 249-274

2. Sadler JE, Blinder M: von Willebrand disease: diagnosis, classification, and treatment. In Hemostasis and Thrombosis: Basic Principles and Clinical Practice. Fourth edition. Edited by Colman RW, Hirsh J, Marder VJ, et al. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, pp 825-837

3. Tefferi A, Nichols WL: Acquired von Willebrand's disease: concise review of occurrence, diagnosis, pathogenesis and treatment. Am J Med 1997;103:536-540

4. Salem RO, Van Cott EM: A new automated screening assay for the diagnosis of von Willebrand Disease. Am J Clin Pathol 2007;127:730-735

Analytic Time

1 day

Method Name

Latex Particle Enhanced Immunoassay

Forms

If not ordering electronically, complete, print, and send a Coagulation Test Request Form (T753) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/coagulation-test-request-form.pdf)