Which factors affect the accuracy of a von Willebrand factor antigen (vWF:Ag) assay?

Updated: Nov 05, 2019
  • Author: Vadim Kostousov, MD; Chief Editor: Eric B Staros, MD  more...
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Answer

Repeated vWF:Ag and vWF:Rco activity testing is sometimes needed to identify low levels of vWF compatible with vWD. A retrospective study showed that about 30% of pediatric patients required a second vWD test before the diagnosis was established. [5] Other tests (vWF collagen-binding assay, vWF multimer analysis, genetic analysis) may also be useful in confirming the diagnosis. [4, 6, 7]  African Americans have vWF:Ag levels that are approximately 20% higher than those in the white population, although their vWF:RCo levels do not differ. [8]  In addition, vWF:Ag increases with age, both in healthy individuals and in those with vWD. [9, 10]


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