Laura Lum, Seattle Children’s Hospital, asks, What is the ristocetin cofactor assay for, how is it performed, and can it be done on an STA Compact?
Hi, Laura, the ristocetin cofactor assay is a test for von Willebrand factor (VWF) activity. Low VWF is the cause of von Willebrand disease (VWD). The assay began as platelet aggregometry in which patient platelet-poor plasma is mixed with preserved reagent platelets such as are provided in Chrono-Log Corp Ristocetin Cofactor Assay Kit. Then ristocetin reagent is added and aggregation is recorded. The degree of tracing deflection estimates the concentration of VWF.
Siemens Healthcare Diagnostics, Inc offers an automated form of the assay, their BC von Willebrand reagent, designed to work on Siemens’ instruments. Several US lab operators have successfully adapted Siemens reagent to Stago equipment, and you can obtain assistance from you account manager or the technical support folks at Stago if you would like to adapt the assay to your instrument. Geo.