Background:
Ever since medical professionals have recognized the important role of ADAMTS-13 in the pathogenesis of TTP, several methods to diagnosis the activity of ADAMTS-13 in the plasma of TTP patients haves been developed. However these assays have not been widely used in practice because they are cumbersome and they require several days to complete. In this study we examine the new, rapid ADAMTS-13 activity assay that uses fluorescence resonance energy transfer and we compared it with the conventional assay to determine its diagnostic advantage.
Methods:Seven TTP patients were compared with 60 healthy controls. The plasma ADAMTS-13 activity was measured using the fluorescence-quenching substrate assay method. The results were compared with the results of performing multimer analysis of SDS-agarose gel electrophoresis.
Results:
It took only 2 hour to complete the fluorescence-quenching substrate assay. The median ADAMTS-13 activity using the fluorescence-quenching substrate was 5.9% (range: 0∼29.9%) for the patient group and 99.1% (range: 74.4∼143.3%) for the healthy group, respectively. The median ADAMTS-13 activity using multimer analysis of SDS-agarose gel electrophoresis was 5.6% (range: 1.6∼28.8%) for the patients group and 87.7% (range: 44.1∼120.9%) for the healthy group, respectively. The ADAMTS-13 activities of the two assays were well correlated (correlation coefficient: 0.69).
Conclusion: The quantification of ADAMTS-13 activity with using the fluorescence-quenching substrate is rapid and highly specific for the diagnosis of TTP and it is expected to be used widely in the diagnosis of TTP.

Keywords: TTP, ADAMTS-13, Assay