Possibility of potential VWD misdiagnosis or misclassification using LIA technology and due to presence of rheumatoid factor.

von Willebrand's disease (VWD) is now recognised to be the most common inherited bleeding disorder and is due to defects and/or deficiencies in von Willebrand factor (VWF). The latex immuno-assay (LIA) procedure has become a popular VWF:Ag detection methodology because of the ability to automate testing. In this report, we present findings which urge caution when normal LIA results are obtained co-incident to striking clinical findings strongly suggestive of VWD, or previous laboratory findings consistent with VWD. As illustrated by a relevant case study, normal LIA results may lead to an "incorrect diagnosis" of "not VWD" or to a potential subtype misdiagnosis, should they be accepted without cross-confirmation using alternative VWF methodologies.