Evaluation of the von Willebrand factor antigen (vWF-Ag) assay using an immuno-turbidimetric method (STA Liatest (R) vWF) automated on the MDA (R)-180 coagulometer

The standard enzyme-linked immunosorbent assay (ELISA) test for von Willebr and factor antigen (vWF-Ag), though sensitive and specific, does not delive r the flexibility to handle single sample assessments economically or provi de rapid, emergency testing capability. The present study examined the perf ormance characteristics of an immunoturbidimetric assay kit (STA Liatest(R) ) modified for automation on the MDA(R)180 coagulation analyser using a sup plied protocol, One hundred and sixteen patient samples were assessed by bo th the standard and the modified method. The correlation coefficient was 0. 98 across the range of values 1-487 IU/dl, Above 200 IU/dl, where specimen dilution was indicated, there was greater diversity (r = 0.86) between the techniques. Plotting the difference between methods against the mean of bot h showed excellent agreement between methods below 100 IU/dl vWF. The intra -assay and interassay coefficients of variation were less than 3% at both l ow and normal range levels. The MDA(R)180 automated vWF assay merits consid eration as an alternative to ELISA testing that provides random access and result availabilty within 30 min.