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

Laboratory Recommendations

VWD NHLBI Guidelines (2008) Summary of Laboratory Recommendations

Slide 24

May 2011

Referencing VWF testing results to the population reference range, rather than to ABO-stratified reference ranges, may be clinically useful. <30 IU/dL VWF is recommended as the “cut-off” for definite VWD diagnosis (especially type 1 VWD). This recommendation does not preclude VWD diagnosis at VWF levels of 30 to 50 IU/dL, if supporting clinical history present, nor does the recommendation preclude treatment to elevate VWF if there is clinical bleeding risk. The high CV of VWD assays (VWF ristocetin cofactor, VWF antigen, factor VIII, and others), coupled with variability of VWF and factor VIII levels contributed by conditions of the patient and the plasma sample, contribute substantially to difficulties in diagnosing VWD or classifying the subtype (eg, types 1 vs. 2A, 2B, or 2M using the VWF ristocetin cofactor to antigen ratio).

Summary of Laboratory Recommendations


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