A Comparison of Two Commercial ADAMTS13 Activity Assays With a Reference Laboratory Method

Background: ADAMTS13 is the enzyme responsible for cleaving ultra-large von Willebrand factor (vFW) multimers. Commercial kits have been recently developed that use a fluorescence resonance energy transfer (FRET) methodology to measure ADAMTS13 activity. Methods: In this study, we compared the results from 2 recently released commercial kits (GTI and Technoclone) with results obtained from a reference laboratory also using FRET technology to assay samples from patients referred for a possible diagnosis of thrombotic thrombocytopenic purpura (TTP). Results: A total of 29 samples were assayed and compared. Six samples had less than 5% of normal ADAMTS13 activity identified by the reference laboratory. The GTI kit identified only 4 of these 6 samples, while the Technoclone kit identified all 6. Conclusion: The results of this study demonstrate that commercial ADAMTS13 activity assays currently available are clinically useful in diagnosing TTP.