Thrombotic Thrombocytopenic Purpura (TTP) — Pathway

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

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Full pathway

1. [Decision] PLASMIC / clinical probability
   PLASMIC score / high clinical suspicion of TTP? (Microangiopathic hemolytic anemia (MAHA) + thrombocytopenia with no other cause → suspect TTP (ADAMTS13 <10%). The pentad (+ neuro/renal/fever) is present in only ~10%. Labs: schistocytes, raised LDH, low haptoglobin, raised indirect bilirubin, normal PT/APTT (distinguishes from DIC), negative Coombs. PLASMIC score (platelets <30, hemolysis, no active cancer/transplant, MCV <90, INR <1.5, Cr <2.0) 6–7 = high risk.)
   • High suspicion (PLASMIC 6–7 or clinical) → High suspicion → plasma exchange
   • Low probability → Low probability
2. [End] Low probability
   Complete ADAMTS13, repeat blood film/hemolysis markers; differentiate DIC (prolonged PT/APTT), HUS, HELLP, malignant hypertension and other thrombotic microangiopathies, and treat accordingly.
3. [End] High suspicion → plasma exchange
   High suspicion — start without waiting for the ADAMTS13 result (after sampling): 1) plasma exchange (PEX, first-line, daily until platelets recover). 2) High-dose corticosteroids. 3) Caplacizumab (anti-vWF, for acquired TTP). 4) Rituximab (acquired immune TTP). Do not transfuse platelets (unless life-threatening/intracranial bleeding — can worsen microthrombosis). ADAMTS13 <10% confirms; ≥20% look for another diagnosis. Hematology consult.

Source guidelines & references

• ISTH TTP diagnosis guideline (2020); PLASMIC score

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

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