von Willebrand factor antigen as an acute phase reactant and marker of endothelial cell injury in connective tissue diseases: a comparison with CRP, rheumatoid factor, and erythrocyte sedimentation rate.

Plasma von Willebrand factor antigen concentrations in 125 patients with connective tissues diseases were compared to the levels of the acute phase reactant C-reactive protein, with rheumatoid factor and with erythrocyte sedimentation rate. There was a positive correlation between von Willebrand factor antigen and C-reactive protein, but no correlation with rheumatoid factor or erythrocyte sedimentation rate. There were, however, a significant number of instances of high C-reactive protein with low von Willebrand factor antigen, and also low C-reactive protein with high von Willebrand factor antigen. Although von Willebrand factor antigen may be regarded as an acute phase reactant, high levels in the absence of other indicators of an acute phase response may be suggestive of damage/injury to the endothelium.