How is complete treatment response determined for thrombotic thrombocytopenic purpura (TTP)?

Updated: Feb 18, 2019
  • Author: Theodore Wun, MD, FACP; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Complete response criteria differ depending on the investigator, but they generally include the following:

  • Resolution of neurologic symptoms

  • Normalization of hemoglobin, platelet count, LDH, and bilirubin levels

  • Normalization of creatinine concentration

Adequate initial response is fulfilled if neurologic signs and symptoms disappear, the platelet count climbs to greater than 50,000/μL, and the LDH level declines. In patients who respond to plasma exchange, the mean time to resolution of neurologic changes is approximately 3 days, to a normal LDH is 5 days, to a normal platelet count is 10 days, and to normal renal function is 15 days.

The total number of exchanges necessary for sustained response is not established. Anecdotally, the rate of relapse is increased if plasma exchange is stopped abruptly, although no prospective, or even retrospective, study has shown this to be true. Regardless, many apheresis services taper the exchanges from three per week to one per week before stopping therapy. In the author's experience, a direct correlation existed between the number of exchanges required to reach a platelet count of 150,000/μL and the risk of relapse.

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