ADAMTS13 and thrombotic thrombocytopenic purpura: However, in most previous studies, ADAMTS13 levels and ADAMTS13 inhibitor were not assessed, and the diagnosis of TTP was based on clinical “pentads” of fever, thrombocytopenia, MAHA, and neurological and/or renal impairment, which may be misleading since considerable overlap exists between TTP and SLE regarding presenting features, and causes of thrombotic microangiopathy (TMA) may vary among lupus patients [11].