USMLE Prep - Medical Reference Library

Immune TTP — ADAMTS13, Plasma Exchange, Steroids, and Caplacizumab

System: Hematology Oncology • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Suspect iTTP with MAHA and thrombocytopenia; send ADAMTS13 urgently and begin plasma exchange plus high-dose steroids immediately; add caplacizumab when iTTP is likely to reduce time to platelet recovery and relapses.

Key Points

  • Stabilize ABCs; treat life‑threatening derangements immediately.
  • Confirm diagnosis early with highest‑yield imaging/labs.
  • Initiate guideline‑based therapy and escalate by response.
  • Plan disposition and follow‑up explicitly.

Clinical Synopsis & Reasoning

Immune TTP is a microangiopathy from severe ADAMTS13 deficiency. Treat presumptively when suspected: daily plasma exchange plus high‑dose corticosteroids. Add caplacizumab early to shorten time to platelet recovery and reduce exacerbations; introduce rituximab to target the autoantibody. Monitor for relapse and complications.

Treatment Strategy & Disposition

Immune TTP is a microangiopathy from severe ADAMTS13 deficiency. Treat presumptively when suspected: daily plasma exchange plus high‑dose corticosteroids. Add caplacizumab early to shorten time to platelet recovery and reduce exacerbations; introduce rituximab to target the autoantibody. Monitor for relapse and complications.

Epidemiology / Risk Factors

  • Risk varies by comorbidity and precipitating factors

Initial Targets

ParameterTarget/Action
HemodynamicsMaintain perfusion; avoid hypotension
MonitoringSerial exam, labs, and imaging
TherapyStart early, reassess, de‑escalate when appropriate

Investigations

TestRole / RationaleTypical FindingsNotes
CBCScreen leukocytosis/anemiaContext‑specificTrend response
BMPElectrolytes/renal functionDerangements commonReplace K+/Mg2+
Key imagingCondition‑specific (CTA/MRI/Endoscopy)See textDo not delay when red flags

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Therapeutic plasma exchangeImmunotherapyImmediateFirst‑line with steroidsAccess/bleeding risks
Caplacizumabanti‑vWF nanobodyHoursAdd when iTTP likelyBleeding risk; with PEX/steroids
MethylprednisoloneGlucocorticoidHoursImmunosuppressionHyperglycemia, infection

Prognosis / Complications

  • Outcome depends on timeliness of diagnosis and definitive therapy

Patient Education / Counseling

  • Explain red flags, adherence, and follow‑up plan

References

  1. ASH Review: Management of iTTP — Link
  2. ISTH TTP Guidelines Update (2025) — Link