Quantitative analysis of von Willebrand factor and its propeptide in plasma in acquired von Willebrand syndrome.

Measurement of the von Willebrand factor (vWF) propeptide, also known as von Willebrand antigen II, has been suggested to be helpful in the discrimination of congenital von Willebrand disease type I from type 2 and in assessing the extent of activation of the endothelium. We performed a quantitative analysis of mature vWF and its propeptide in plasma in 8 patients with acquired von Willebrand syndrome (AvWS) and in 20 normal individuals. Mature vWF levels were significantly lower in AvWS as compared with normal individuals (13.4+/-3.5 vs 35.6+/-3.3 nM, p <0.001). In contrast, propeptide levels were significantly higher in AvWS (11.4+/-1.1 vs 4.7+/-0.2 nM, p <0.001), probably reflecting a compensatory increase in vWF synthesis or increased perturbation of the endothelium in AvWS. After treatment with DDAVP, propeptide and mature vWF levels rose 5-fold in AvWS, whereas propeptide levels were not altered by the infusion of a vWF concentrate or treatment with high dose intravenous immunoglobulins, indicating that plasma propeptide levels are a reliable reflection of vWF synthesis. Measurement of propeptide levels may provide additional information in AvWS as to whether decreased levels of mature vWF in the circulation are due to a decrease in synthesis or due to an accelerated removal of vWF from the circulation.