Use

ADAMTS‑13 is a zinc metalloprotease responsible for cleaving ultra‑large von Willebrand factor multimers. Reduced ADAMTS‑13 activity is associated with thrombotic thrombocytopenic purpura (TTP), a life‑threatening hematologic condition marked by thrombocytopenia, microvascular thrombi, hemolytic anemia, and potential renal impairment. Congenital TTP arises from mutations in the ADAMTS‑13 gene producing nonfunctional enzyme, while the acquired form stems from autoantibodies that inhibit ADAMTS‑13 activity. Reflex testing for ADAMTS‑13 inhibitor is triggered when activity is ≤0.30 IU/mL. Results are reported in IU/mL (activity) and Bethesda equivalent units for inhibitor. This test aids in differentiating congenital vs acquired TTP and informing therapeutic decisions.