George JN. How I treat patients with thrombotic thrombocytopenic purpura: Blood. 2010;116(20):4060–4069.

Data from all 65 patients presenting between November 13, 1995, and December 31, 2009, with ADAMTS13 activity less than 10%, by immunoblotting and/or FRETS assays, are presented. Neurologic abnormalities and renal failure categories have been previously defined.¹⁷ Neurologic abnormalities and laboratory data are from the day of diagnosis, defined as the day of the first plasma exchange treatment. Renal failure categories included data at diagnosis plus or minus 7 days. Laboratory data and the number of plasma exchange treatments are presented as median values and ranges. LDH values are normalized to an upper limit of normal of 200 U/L. The woman with a hematocrit of 43% had not been transfused; she had red cell fragments on her peripheral blood smear, a platelet count of 22 000/μL, LDH of 1613 U/L, and neurologic abnormalities; 2 days later, her hematocrit was 22%. No other untransfused patient had a hematocrit greater than 33% on the day of diagnosis. The woman with a platelet count of 124 000/μL had not received a platelet transfusion; she was comatose, had a hematocrit of 25% with red cell fragments on the peripheral blood smear, LDH of 418 U/L, and acute renal failure. The next highest (untransfused) platelet count on the day of diagnosis was 69 000/μL. Both the woman with the hematocrit of 43% and the woman with a platelet count of 124 000/μL had idiopathic TTP. Deaths occurred within 30 days of the last plasma exchange treatment.

Data are from the day of diagnosis for determining the “classic pentad” of clinical features. For neurologic abnormalities, both major and minor abnormalities were included; serum creatinine greater than 1.5 mg/dL was considered a renal abnormality.

Data are the number of plasma exchange treatments and the range.