Guideline Video

Guideline Resources

  • Title: Diagnosis & Treatment of Thrombotic Thrombocytopenic Purpura
  • Society: International Society on Thrombosis and Haemostasis (ISTH)
  • Publish Date: June 17, 2025
  • Guideline Summary
  • Full-text

Video Transcription

Today we’ll be going over The International Society on Thrombosis and Haemostasis’s newest guideline on Diagnosis & Treatment of Thrombotic Thrombocytopenic Purpura (TTP).

The objective of this guideline is intended to support patients, clinicians, and other health care professionals in their decisions about the initial diagnosis and management of acute TTP.

There are 3 recommendations, so let’s get started

  • In settings with a timely access to plasma ADAMTS13 activity testing and for patients with a high clinical suspicion of immune-mediated Thrombotic Thrombocytopenic Purpura (iTTP), the guideline suggests the following diagnostic strategy.
    • Step 1: Acquire a plasma sample for ADAMTS13 testing before an initiation of TPE or use of any blood product.
    • Step 2: Start TPE and corticosteroids without waiting for the results of ADAMTS13 testing.
    • Step 3: Consider early administration of caplacizumab before receiving plasma ADAMTS13 activity results.
    • Step 4: When the result of plasma ADAMTS13 activity is available, continue caplacizumab if ADAMTS13 activity is less than 10 IU/dL or stop caplacizumab and consider other diagnoses if ADAMTS13 activity is >20 IU/dL.
    • Step 5: For patients with plasma ADAMTS13 activity less than 10 IU/dL, also consider adding rituximab as early as possible, as a majority of these adult patients have autoantibodies against ADAMTS13.
  • In settings with a timely access to plasma ADAMTS13 testing and for patients with intermediate or low clinical suspicion of iTTP, the panel suggests the following diagnostic strategy.
    • Step 1: Acquire a plasma sample for ADAMTS13 testing before an initiation of TPE or use of any blood product.
    • Step 2: Consider starting TPE and corticosteroids, depending on the clinician's judgment and assessment of the individual patient.
    • Step 3: Do not start caplacizumab until the result of plasma ADAMTS13 activity becomes available.
    • Step 4: When the result of plasma ADAMTS13 activity testing is available, consider adding caplacizumab and rituximab if ADAMTS13 activity is less than 10 IU/dL with inhibitors or an elevated level of anti-ADAMTS13 IgG, but do not start caplacizumab and consider other diagnoses if ADAMTS13 activity is greater than 20 IU/dL.
  • In settings of no reasonable access to plasma ADAMTS13 activity testing, the panel suggests that caplacizumab not be used, regardless of the pretest probability of TTP.

And there you have it. Make sure to check out the full guideline from The International Society on Thrombosis and Haemostasis and other related clinical decision support tools at guidelinecentral.com.

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