Quantification and Facilitated Comparison of von Willebrand Factor Multimer Patterns by Densitometry

The analysis of von Willebrand factor (vWF) multimers is an important laboratory tool for distinguishing among the numerous subtypes of von Willebrand disease (vWD). Comparability and reproducibility of this method are insufficient; standardization and external references are pending. Interlaboratory comparison of results therefore may be difficult. We applied densitometry to obtain a reproducible quantification of vWF multimer patterns in healthy donors, patients with vWD variants, and factor VIII/vWF concentrates to improve the reproducibility and comparability of vWF multimer analysis. Multimers were separated and visualized luminographically on x-ray films. Films were scanned and evaluated by densitometry. The variation inherent in vWF multimer analysis and the range of the normal could be quantified. In vWD variants and factor VIII/vWF concentrates, densitometry could quantify and visualize alterations of vWF multimer patterns and facilitate their comparison. Densitometry permits a precise quantitative comparison of sample patterns to a reference plasma. It could be a valuable tool offering reproducible quantification and additional visualization of normal and pathologic vWF multimer patterns, facilitating their comparison and contributing to a standardization of vWF multimer analysis.