Context.—: Immune thrombotic thrombocytopenic purpura (iTTP) is a rare but potentially fatal blood disorder resulting from acquired deficiency of plasma ADAMTS13, a metalloprotease that cleaves endothelium-derived ultralarge von Willebrand factor. Standard of care for iTTP including therapeutic plasma exchange, caplacizumab, and immunosuppressives, known as triple therapy, has led to a significant reduction in the disease-related mortality rate. The first International Society of Thrombosis and Haemostasis TTP guideline stresses the importance of having plasma ADAMTS13 activity testing in the algorithm for diagnosis and management of iTTP. However, the predictive role of assessing plasma ADAMTS13 activity and inhibitors or other ADAMTS13-related parameters in patients with acute iTTP and during remission has not been systematically evaluated.
Objective.—: To review and assess the predictive values of testing plasma ADAMTS13 activity, antigen, and inhibitors or anti-ADAMTS13 immunoglobulin G at various stages of disease in outcomes of iTTP.
Data sources.—: Peer-reviewed publications and personal experience.
Conclusions.—: We conclude that assessing ADAMTS13 biomarkers is not only essential for establishing the initial diagnosis, but also crucial for risk stratification and the early detection of disease recurrence. This may guide therapeutic interventions during acute episodes and for long-term follow-up of iTTP patients.
© 2023 College of American Pathologists.