Von Willebrand-Related Test Abnormalities
Low value for von Willebrand factor (vWF) and/or ristocetin cofactor (RCoF) or values in the low end of these normal ranges with a history of mild bleeding affecting males and females in the family suggest von Willebrand disease (vWD).
vWD could be type 1, 2A, 2B, 2M, 2N, or 3.
A person with blood type O who does not have vWD, since persons with blood type O have a mean vWF of only about 75% of normal.
Suggested Additional Lab Testing
RCoF, vWF, and factor VIII level (factor VIII level often decreases along with the other 2).
In type 1 vWD, RCoF and vWF are suppressed approximately equally and mildly abnormal.
In type 2, vWF is typically greater than or equal to 15% greater than RCoF, and the values for both are in the 20% range or lower.
In type 3, both of these values approximate 0.
Fibrinogen is an important measurement, because it is an acute phase reactant.
Fibrinogen elevation suggests that RCoF and vWF levels do not represent the patient's true baseline values and that a repeat test at a later time is necessary.
Obtain blood type: mean value for vWF varies with blood type.
VWF multimer analysis by agarose gel electrophoresis and Western blotting is useful when there is a high likelihood of non-type 1 vWD.
Desmopressin (DDAVP) stimulation test (except if the patient has type 2B or platelet type vWD) may be useful to determine if DDAVP can be used clinically to treat vWD.
In the test, samples for RCoF and vWF are taken before DDAVP administration and then again 60 minutes after completion of a 30-minute infusion of DDAVP.
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