Introduction Thrombotic thrombocytopenic purpura (TTP) is a rare life‐threatening thrombotic microangiopathy (TMA) characterized by the severe deficiency of ADAMTS13 activity (<10%). Rapid ADAMTS13 testing is crucial for early diagnosis and optimal management of TTP patients and other TMAs. The objective of this study was to retrospectively evaluate the performance of the recently commercialized HemosIL Acustar® ADAMTS13 activity chemiluminescent immunoassay (Instrumentation Laboratory, Bedford, Massachusetts, United States) in a multicentric study between Spain and Portugal. Methods A comparison method was performed to compare HemosIL Acustar® with an in‐house FRETS‐VWF73 assay and two commercial ELISA assays: the TECHNOZYM® ADAMTS13 Activity (Technoclone GmbH, Vienna, Austria) and the DG‐EIA ADAMTS‐13 Activity (Diagnostic Grifols, SA, Barcelona, Spain). A set of 241 frozen plasma samples with known ADAMST13 levels was used. Agreement between methods was assessed with focus on two cut‐off ADAMTS13 activity values: <10% (the clinical accepted cut‐off value to confirm TTP diagnosis) and <5%. Results HemosIL AcuStar® showed high agreement with the other methods in correctly classify patients with ADAMTS13 values below 10% (Kappa = 0.89) and even below 5% (Kappa = 0.94) with no false negatives and few false positives (5.40%; 95% CI: 2.20 to 8.60%). However, it also tended to underestimate ADAMTS13 levels, especially for the high assay range values (>40%) (absolute mean bias of 8.40% (95% CI: 6.53 to 10.42%)) when compared to other assays. Conclusions HemosIL AcuStar® is highly sensitive to detect ADAMTS13 values below 10% and 5%. A large prospective validation study is needed to corroborate its utility in clinical practice.

Immunosuppressive treatment and bypassing agents are used to treat acquired haemophilia A (AHA). On the other hand, COVID-19 infection induces a hypercoagulable state. Managing bleeding, risk of thrombosis, bypassing agents, active infection and immunosuppressive treatment can be challenging. A 72-year-old man was diagnosed with acquired hemophilia A. He received steroids, rituximab and recombinant activated factor VII (rFVIIa). He developed severe SARS-CoV-2 infection. Due to thrombotic risk, he received low-molecular-weight heparin (LMWH) and developed an iliopsoas hematoma. Because of the risk of thrombosis, treatment with recombinant porcine FVIII (rpFVIII) was requested. Tocilizumab was administered for treatment of SARS-CoV-2 infection and unexpected improvement of FVIII levels was noted. Concluding, rpFVIII treatment was well tolerated and effective, easy to monitor and to administer. Tocilizumab may play a role as immunosuppressive treatment for AHA. The role of LMWH remains to be established in patients with coagulopathies.