Sorted By Test Name - Mayo Medical Laboratories

VWPR
83099
Inherited vWD has been classified into 3 types: -Type 1, typically an autosomal dominant disease, is the
most common, accounting for approximately 70% of vWD patients. It represents a quantitative deficiency
of VWF of variable severity. -Type 2, which is usually an autosomal dominant disease, is characterized by
several qualitative abnormalities of vFW. Four subtypes have been identified: 2A, 2B, 2M, and 2N. -Type
3, an autosomal recessive disorder, leads to severe disease with extremely reduced or undetectable levels
of VWF, as well as very low factor VIII. Acquired von Willebrand syndrome (AVWS) is associated with
a number of different disease states and is caused by several different pathophysiological mechanisms,
including antibody formation, proteolysis, binding to tumor cells with increased clearance, and decreased
synthesis. AVWS is most frequently described in patients with dysproteinemias (including monoclonal
gammopathy of undetermined significance [MGUS], multiple myeloma, and macroglobulinemia),
lymphoproliferative disorders, myeloproliferative disorders (eg, essential thrombocythemia), autoimmune
diseases (eg, systemic lupus erythematosus), severe aortic stenosis, gastrointestinal angiodysplasia, and
hypothyroidism.
Useful For: Subtyping of von Willebrand factor: -When results of complementary laboratory tests (eg,
F8A/9070 Coagulation Factor VIII Activity Assay, Plasma; VWFX/89792 von Willebrand Activity,
Plasma; and VWAG/9051 von Willebrand Factor Antigen, Plasma) are abnormally low or discordant.
-This test is primarily used to identify variants of type 2 von Willebrand factor. -As an aid determining
appropriate treatment
Interpretation: The plasma von Willebrand factor (VWF) multimer analysis is a qualitative visual
assessment of the size spectrum and the banding pattern of VWF multimers. This test is used to identify
variants of type 2 von Willebrand disease that have fewer of the largest multimers, have unusually large
multimers, or have qualitatively abnormal "bands" that indicate an abnormal VWF structure.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Budde U, Schneppenheim R: von Willebrand Factor and von Willebrand
Disease. Rev Clin Exp Hematol 2001;5.4:335-368 2. Ruggeri ZM: Structure and function of von
Willebrand factor: Relationship to von Willebrandâ€s disease. Mayo Clinic Proc 1991;66:847-861 3.
Sadler JE: A revised classification of von Willebrand disease. Thromb Haemost 1994;71:520-525 4.
Laffan M, Brown SA, Collins PW, et al: The diagnosis of von Willebrand disease: a guideline from the
UK Haemophilia Centre Doctors Organization. Haemophilia 2004;10:199-217 5. Mannucci PM:
Treatment of von Willebrandâ€s disease. N Engl J Med 2004;351:683-694 6. Pruthi RKl: Plasma von
Willebrand factor multimer quantitative analysis by in-gel immunostaining and infrared fluorescent
imaging. Thromb Res 2010;126:543-549
von Willebrand Profile
Clinical Information: von Willebrand factor (VWF) is synthesized by the endothelial cell and
megakaryocyte and is present in these cells, as well as in platelets, subendothelial tissue, and plasma.
VWF serves as an adhesive protein important in adhering platelets to subendothelial tissue at the site of
vascular injury and for adhering platelets to each other (aggregation). Platelet adhesion and aggregation
are essential to form a mechanical hemostatic "plug" and as the focus for interaction of clotting factors
and phospholipid required for the formation of the fibrin platelet clot. VWF also stabilizes plasma factor
VIII by binding it and protecting it from proteolysis and serves as a carrier protein for that clotting factor.
VWF circulates in the blood in 2 distinct compartments. 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. Plasma VWF circulates normally in multimeric forms with molecular weights ranging from
500,000 to as much as 20,000,000. The high- molecular-weight (HMW) forms of VWF are the most
effective components for interaction with platelets. This primary activity of plasma VWF is measured in
the laboratory with the VWF activity assay, whereas VWF antigen testing measures the amount of VWF
protein, and factor VIII coagulant activity indirectly reflects VWF interaction with factor VIII. VWF
multimer analysis visualizes the distribution of VWF multimers and is useful as a reflexive test for
subtyping von Willebrand disease (VWD). Levels of factor VIII, VWF antigen, and VWF activity may
vary greatly within each individual over time and also with blood type (normal type "O" individuals may
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