Diagnosis of TTP Complete blood count (CBC) with platelets, peripheral blood smear, reticulocyte count, direct antiglobulin (Coombs) test, lactate dehydrogenase (LDH), prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen, haptoglobin, and serum bilirubin (direct and indirect) Urinalysis and renal function tests ADAMTS 13 activity and autoantibody levels Exclusion of other thrombocytopenic disorders Thrombotic thrombocytopenic purpura is suspected in patients with suggestive symptoms, thrombocytopenia, and anemia.