Abstract
Background Acquired von Willebrand syndrome (AVWS) is frequent in patients with myeloproliferative
neoplasms (MPNs). For von Willebrand factor (VWF) functional evaluation, ristocetin
cofactor activity by aggregometry (VWF:RCo) is considered the gold standard but has
limitations, and automated activity measurement has been developed such as the HemosIL
VWF:RCo Werfen with particle agglutination (VWF:GPIbR).
Objectives To evaluate the performance of VWF:GPIbR with HemosIL VWF:RCo Werfen (VWF:GPIbR)
versus VWF:RCo in patients with thrombocytosis in the context of MPNs (T-MPNs) and
in patients with secondary thrombocytosis (ST).
Methods MPN patients with thrombocytosis >450 G/L (T-MPNs) were compared with patients with
ST due to inflammation or iron deficiency. VWF activity (VWF:Act) was analyzed using
VWF:RCo or VWF:GPIbR. VWF analysis was completed by analysis of VWF multimers and
VWF collagen binding (CB) assay (VWF:CB).
Results A total of 33 T-MPNs and 18 ST patients were included. Compared with aggregometry,
evaluation of VWF:Act by VWF:GPIbR led to lower values in T-MPN patients, but also
in ST patients. Interestingly, although the VWF:RCo/VWF:Ag ratio did not reveal differences
between T-MPNs and ST patients, the VWF:GPIbR/VWF:Ag ratio analysis allowed us to
suspect AVWS only in T-MPN patients. Using the distribution of VWF multimer analysis
and VWF:CB, we here demonstrated that VWF:GPIbR allows AVWS diagnosis in nine T-MPNs
as opposed to aggregometry.
Conclusion Evaluation of VWF:Act using VWF:GPIbR has a greater sensitivity compared with aggregometry
to detect AVWS in T-MPN patients.
Keywords
acquired von Willebrand syndrome - myeloproliferative neoplasms - thrombocytosis
