A novel assay for evaluating ADAMTS13 activity may be both fast and reliable for the diagnosis of thrombotic thrombocytopenic purpura (TTP), according to the results of a study published in Research and Practice in Thrombosis and Hemostasis.

A thrombotic microangiopathy that can be life-threatening, TTP can be diagnosed only through measurement of ADAMTS13 activity, which is deficient in the TTP setting. Determination of ADAMTS13 activity is, however, both difficult and time-consuming, suggesting a need for novel assays when TTP is suspected.

The HemosIL AcuStar ADAMTS13 activity assay, a novel, automated chemiluminescent technique, has shown promise in previous evaluation for quickly and correctly determining ADAMTS13 levels. For this study, researchers evaluated whether the HemosIL AcuStar ADAMTS13 activity assay is superior to an in-house assay, FRETS-VWF73, which was developed by the same corporation for measuring ADAMTS13 activity in a patient cohort. The study had both a retrospective and prospective evaluation cohort.

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The novel assay was used on 539 citrated plasma samples. Compared with the FRETS-VWF73 assay, the HemosIL AcuStar ADAMTS13 activity assay’s results accounted for more than 80% of the variance in test results (r2 = .83; P <.0001). The novel assay’s specificity was 99.7%, with a positive predictive value of 99.2%.

These test results appeared robust, furthermore, with ADAMTS13 activity in the low (0-25 IU/dL) and undetectable (less than 10 IU/dL) ranges.

“This method could thus replace current techniques as a first-line assay for both TTP initial diagnosis and follow-up, with an obvious benefit for therapy-driven monitoring,” the authors wrote. “However, confrontation with clinical data remains crucial, and if ADAMTS13 activity appears to conflict with clinical presentation, it must be controlled with a reference method in experienced laboratories.”

Disclosures: Some authors have declared affiliations with or received funding from the pharmaceutical industry. Please refer to the original study for a full list of disclosures.


Beranger N, Benghezal S, Joly BS, et al. Diagnosis and follow‐up of thrombotic thrombocytopenic purpura with an automated chemiluminescent ADAMTS13 activity immunoassay. Res Pract Thromb Haemost. Published online December 15, 2020. doi:10.1002/rth2.12461