The rapid differential diagnostic value of the von Willebrand factor GPIb activity/antigen ratio for thrombotic thrombocytopenic purpura / 中华检验医学杂志

ABSTRACT

Objective:To evaluate the diagnostic value of the von Willebrand factor (vWF) GPIb activity to antigen ratio for thrombotic thrombocytopenic purpura (TTP) at acute phase.Methods:A cohort of 93 patients with suspected TTP and admited to our hospitalfrom January 2018 to December 2019 were prospectively enrolled, we analyzed the levels of vWF GPIb activity and vWF antigen at acute phase, the diagnosis of acquired TTP was defined as ADAMTS13 activity<10%.The PLASMIC score and final diagnosis of included patients were recorded.Results:Twenty-twopatients were diagnosed as TTP, the median (interquartile range) of ADAMTS13 activity were 1.0% (0-7.4%), other diagnoses included hemolytic uremic syndrome (HUS, n=8), severe infection ( n=21), malignancy( n=3), connective tissue disease( n=8), et al. The vWF GPIb activity, vWF antigen, and ratio of vWF GPIb activity to antigen were all significantly lower in patients with TTP than in those without ( P<0.05). The ratio of vWF GPIb activity to vWF antigen <0.75 could yield a sensitivityof 81.8% and a specificity of 95.2% respectively for TTP. In patients with PLASMIC score≥6, 88.9% patients with the ratio of vWF GPIb activity to vWF antigen <0.75 were confirmed as TTP, and 15.4% patients with the ratio≥0.75 were confirmed as TTP. Conclusions:The ratio of vWF GPIb activity to vWF antigen based on automaticassays might be useful for differential diagnosis and stratification of TTP at acute phase, especially when the ADAMTS13 assay is not available in time.