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

Laboratory Recommendations

VWD NHLBI Guidelines ABO Blood Group and VWF/VWD: Soft Recommendations

Slide 18

May 2011

Although it has been recommended to stratify reference ranges for VWF antigen and VWF ristocetin cofactor activity with respect to blood group O and non-group O, evolving limited information supports the concept that, despite the ABO blood grouping and associated reference ranges, the major determinant of bleeding risk is low VWF.

Therefore, referencing VWF testing results to the population reference range, rather than to ABO-stratified reference ranges, may be more useful clinically. However, it is important to remember that apparently normal persons may have "mildly low" VWF; and that a majority of persons with clinical type 1 VWD have blood group O.

Soft Recommendations


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