ADAMTS13 and thrombotic thrombocytopenic purpura: However, the patient had a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs, member 13 (ADAMTS13) levels of 41.7% (normal range 70–120%) and tested negative for ADAMTS13 inhibitors and thrombotic thrombocytopenic purpura.