[A micromethod of determining the Willebrand factor in blood].

The suggested method for Willebrand's factor detection differs from the known methods by a 2-3 times higher sensitivity and takes 10 times less blood. The technique is based on estimation of washed formalin-treated donor platelet ristomycin aggregation index by scintillating these cells in Laborskel automated scintillator in supernatants of 2 samples with 0.1% ristomycin solution after the tested platelet-free plasma is added to one of these samples. Willebrand's factor level is found on the calibration curve of standard dilutions of a mixture of platelet-free donor plasma. The method is sufficiently simple, operative, and sensitive; it permits the diagnosis of not only Willebrand's disease, but of the hyperaggregation syndromes associated with vascular endothelium involvement that occur in various conditions, as well; it helps monitoring the efficacy of substitute and antiaggregation therapy.