Laboratory identification of von Willebrand disease: technical and scientific perspectives

The correct diagnosis and classification of von Willebrand disease (von Willebrand disorder; vWD) is crucial because the presenting biological activity of von Willebrand factor (vWF) determines both the hemorrhagic risk and subsequent clinical management. Many laboratory assays are employed, given that assay limitations and vWD heterogeneity results in no single test being able detect all forms of vWD. Minimal laboratory identification requires assessments of vWF:antigen, factor (F) VIII:coagulant activity, and functional vWF (using vWF:ristocetin cofactor activity and vWF:collagen-binding activity). Tests to help subclassify vWD include ristocetin-induced platelet aggregation, vWF:multimers, and vWF:FVIII binding assays. New diagnostic developments are now influencing vWD diagnosis, including advancements in methodologies, automation, new platelet function analyzers, genetic mutational analysis, and a better understanding of therapeutic pharmacokinetics. This review focuses on the current recommended laboratory process for investigation of vWD from a practical scientific technical laboratory perspective. Selection of appropriate combination test panels and testing sequence is crucial for the proper diagnosis and classification of congenital vWD.