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Thrombotic Thrombocytopenic Purpura Management (ISTH 2025)

Thrombotic Thrombocytopenic Purpura Management (ISTH 2025): Suspected TTP → Initial Evaluation → Calculate PLASMIC Score → PLASMIC Score Result → Score ...

Pathway Overview

13 steps

Algorithm Steps

13 total

  1. 01Start

    Suspected TTP

    MAHA + thrombocytopenia without alternative explanation

  2. 02Action

    Initial Evaluation

    Confirm microangiopathic hemolytic anemia

    • CBC with smear (schistocytes)
    • Reticulocyte count (elevated)
    • LDH (markedly elevated)
    • Haptoglobin (low/absent)
    • Indirect bilirubin (elevated)
    • Direct Coombs (negative)
    • Creatinine, troponin
  3. 03Action

    Calculate PLASMIC Score

    Predict likelihood of ADAMTS13 <10%

    • Platelet count <30 (+1)
    • Hemolysis (retic>2.5%, haptoglobin absent, indirect bili>2) (+1)
    • No active cancer (+1)
    • No stem cell/organ transplant (+1)
    • MCV <90 (+1)
    • INR <1.5 (+1)
    • Creatinine <2.0 (+1)
  4. 04Decision

    PLASMIC Score Result

    Risk stratify for TTP

  5. 05Action

    Score 0-4: Low Risk

    Consider alternative diagnoses

    • HUS (especially if diarrhea, Shiga toxin)
    • Drug-induced TMA
    • DIC
    • Severe preeclampsia/HELLP
    • Still send ADAMTS13
  6. 06Action

    Score 5: Intermediate

    Clinical judgment required

    • Send ADAMTS13 urgently
    • Consider empiric TPE if high suspicion
    • Close monitoring
  7. 07Action

    Initiate TTP Treatment

    Start immediately for high-risk patients

    • Plasma exchange (TPE) - 1-1.5 plasma volumes daily
    • Corticosteroids (methylpred 1g IV x3 days or pred 1mg/kg)
    • Caplacizumab 11mg IV then 11mg SQ daily
    • Send ADAMTS13 activity and inhibitor BEFORE TPE
    • Avoid platelet transfusion unless life-threatening bleeding
  8. 08Decision

    ADAMTS13 Result

    Confirms or excludes TTP

  9. 09Action

    ADAMTS13 <10%: Confirmed iTTP

    Continue full TTP therapy

    • Continue daily TPE until plt >150 x2 days
    • Continue caplacizumab 30 days post-TPE
    • Rituximab 375mg/m² weekly x4 if inhibitor present
    • Taper steroids over weeks
    • Monitor for relapse (ADAMTS13 q1-3 months)
  10. 10Outcome

    TTP Remission

    Platelets normalized, ADAMTS13 recovering

  11. 11Outcome

    Refractory TTP

    Consider twice-daily TPE, splenectomy, or N-acetylcysteine

  12. 12Action

    ADAMTS13 >20%: Not TTP

    Pursue alternative diagnosis

    • Stop TPE if started empirically
    • Consider: aHUS, drug-TMA, malignancy-associated
    • For aHUS: complement testing, eculizumab
    • Hematology consultation
  13. 13Warning

    Score 6-7: High Risk

    Treat as TTP - do not wait for ADAMTS13

  14. Path rejoins step 07Shared downstream outcome

Guideline Source

2025 focused update of the 2020 ISTH guidelines for management of thrombotic thrombocytopenic purpura

DOI: 10.1016/j.jtha.2025.06.002View Guideline

Clinical Safety Information

Clinical Decision Support — Not a Substitute for Clinical Judgment

Individual patient factors may require deviation from these recommendations.

Known Limitations

  • ADAMTS13 results may not be immediately available
  • PLASMIC score is not diagnostic - clinical judgment required
  • Does not cover congenital TTP in detail
  • Plasma exchange availability varies by institution

Applicable Regions

USEUGlobal

EU: Caplacizumab EMA-approved for iTTP

US: Caplacizumab FDA-approved for iTTP

Version 1Next review: 2028-01-01

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Frequently Asked Questions

What is the Thrombotic Thrombocytopenic Purpura Management (ISTH 2025)?

The Thrombotic Thrombocytopenic Purpura Management (ISTH 2025) is a emergency clinical algorithm for Hematology & Oncology. It provides a structured decision tree to guide clinical decision-making, based on 2025 focused update of the 2020 ISTH guidelines for management of thrombotic thrombocytopenic purpura.

What guideline is the Thrombotic Thrombocytopenic Purpura Management (ISTH 2025) based on?

This algorithm is based on 2025 focused update of the 2020 ISTH guidelines for management of thrombotic thrombocytopenic purpura (DOI: 10.1016/j.jtha.2025.06.002).

What are the limitations of the Thrombotic Thrombocytopenic Purpura Management (ISTH 2025)?

Known limitations include: ADAMTS13 results may not be immediately available; PLASMIC score is not diagnostic - clinical judgment required; Does not cover congenital TTP in detail; Plasma exchange availability varies by institution. Individual patient factors may require deviation from these recommendations.

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