ADAMTS13 and thrombotic thrombocytopenic purpura: In TTP, replacement fluid with plasma provides a source of functional A Disintegrin and Metalloprotease with ThromboSpondin type 1 motif, member 13 (ADAMTS13) that is lacking in these patients, and following TPE treatment with plasma, clinical outcome measures that are disease specific for TTP are already used to monitor the effect of TPE (eg, mortality, measurement of ADAMTS13 levels, platelet count, and lactate dehydrogenase level).9