Key Takeaways

Recent onset of thrombocytopenia and hemolytic anemia is consistent with a diagnosis of Evans syndrome, thrombotic microangiopathies (such as thrombotic thrombocytopenic purpura [TTP], hemolytic uremic syndrome [HUS] or disseminated intravascular coagulation [DIC]), infection or primary bone marrow process such as acute leukemia.

TTP is distinguished from other types of thrombotic microangiopathies by virtue of normal (or near normal) renal function and coagulation assays.

The classic clinical pentad of hemolytic anemia, thrombocytopenia, fever, acute kidney injury, and severe neurologic findings occurs in less than 10% of patients (but is still found on board exams!)

Diagnosis of TTP is:

  • Suggested in a patient with isolated microangiopathic hemolytic anemia, thrombocytopenia, and evidence of organ dysfunction, especially brain or heart, and further supported by a high PLASMIC score.
  • Confirmed by low ADAMTS13 activity levels (<10%).

Treatment is typically initiated in patients with high pretest probability of having TTP before ADAMTS13 activity levels are known.

First-line therapy for patients who have a high probability of TTP (based on clinical assessment +/- clinical prediction score) consists of plasma exchange and steroids.

Other therapies may be considered, including rituximab and caplacizumab, but these are added to plasma exchange/steroids, rather than replacing them.

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