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Von Willebrand Disease (VWD)
Part 2: NHLBI Diagnosis Guidelines

Laboratory Recommendations

VWD NHLBI Guidelines 2008 Initial Patient Evaluation — Laboratory1

Slide 6

May 2011

These 3 initial tests for VWD (VWF antigen, ristocetin cofactor activity, factor VIII) not only screen for VWD (or help exclude it), but are used to assist in classifying VWD if it is present (eg, differentiating type 1 from types 2 or 3 VWD) – this is a Grade B, level III recommendation. The reference standards for these 3 tests are critical and should be referenced to the World Health Organization (WHO) standard. If referenced to the WHO standard, these 3 test results can or should be reported in IU (international units) – where IU/dL is equivalent to % (the latter [%] is commonly used for reporting coagulation factor levels relative to the mean normal level).

Initial Patient Evaluation — Laboratory1


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