Suspected Thrombotic Microangiopathy (TMA)
MAHA + thrombocytopenia
All Pathways
NephrologyEmergency
TTP/HUS Thrombotic Microangiopathy Management (ISTH 2024)
TTP/HUS Thrombotic Microangiopathy Management (ISTH 2024): Suspected Thrombotic Microangiopathy (TMA) → TMA Recognition → Initial Workup → PLASMIC Score...
Pathway Overview
12 steps
Algorithm Steps
12 total
01Start 02Warning TMA Recognition
Classic pentad (rarely complete)
- CORE FEATURES:
- 1. Microangiopathic hemolytic anemia (MAHA)
- - Schistocytes on smear
- - Elevated LDH
- - Low haptoglobin
- - Indirect hyperbilirubinemia
- - Negative Coombs
- 2. Thrombocytopenia
- CLASSIC PENTAD (TTP):
- - MAHA, Thrombocytopenia
- - Fever, Neurologic changes, Renal dysfunction
03Action Initial Workup
Confirm MAHA and rule out mimics
- STAT LABS:
- - CBC with smear (schistocytes)
- - LDH, haptoglobin, indirect bilirubin
- - Coombs (direct antiglobulin test)
- - BMP, creatinine
- - PT/INR, PTT, fibrinogen, D-dimer
- - Pregnancy test
- SEND:
- - ADAMTS13 activity + inhibitor
- - Complement (C3, C4)
- - Stool culture/shiga toxin (if diarrhea)
04Action PLASMIC Score
Predicts severe ADAMTS13 deficiency
- 1 point each:
- - Platelet count <30,000
- - Hemolysis (retic >2.5%, haptoglobin undetectable, indirect bili >2)
- - No active cancer
- - No transplant history
- - MCV <90 fL
- - INR <1.5
- - Creatinine <2.0
- INTERPRETATION:
- - 0-4: Low probability TTP
- - 5: Intermediate
- - 6-7: HIGH probability TTP
05Decision Likely Etiology?
Based on clinical picture
06Action TTP (Acquired or Congenital)
ADAMTS13 deficiency
- ADAMTS13 <10% confirms TTP
- Don't wait for results if high suspicion
- ACQUIRED TTP:
- - Autoantibody to ADAMTS13
- - More common
- CONGENITAL TTP (Upshaw-Schulman):
- - Inherited ADAMTS13 deficiency
- - Rare
07Warning TTP Treatment
PLASMA EXCHANGE IS LIFESAVING
- PLASMA EXCHANGE (PLEX):
- - Start ASAP (don't wait for ADAMTS13)
- - 1-1.5 plasma volumes daily
- - Continue until platelets >150 x 2 days
- CORTICOSTEROIDS:
- - Methylprednisolone 1g IV x 3 days
- - Then prednisone 1 mg/kg
- CAPLACIZUMAB (anti-vWF):
- - 11 mg IV then 11 mg SC daily
- - Reduces time to remission
- RITUXIMAB:
- - For refractory/relapsing
- - 375 mg/m² weekly x 4
08Action Monitoring
Track response to therapy
- DAILY:
- - Platelet count
- - LDH
- - Hemoglobin
- RESPONSE CRITERIA:
- - Platelets >150,000 x 2 days
- - Normalizing LDH
- - No new symptoms
- REFRACTORY:
- - No improvement after 3-5 PLEX
- - Add rituximab
09Outcome Outcomes
Prognosis
- TTP with PLEX: Survival >90%
- TTP without treatment: 90% mortality
- aHUS with eculizumab: Excellent renal outcomes
- STEC-HUS: Usually self-limited
- Relapse risk: 20-40% for TTP
10Action HUS
Typical (STEC) vs Atypical (aHUS)
- TYPICAL HUS (STEC-HUS):
- - Shiga toxin-producing E. coli
- - Bloody diarrhea prodrome
- - Children > adults
- - Supportive care, usually resolves
- ATYPICAL HUS (aHUS):
- - Complement dysregulation
- - No diarrhea prodrome
- - Renal failure prominent
- - Needs complement inhibitor
11Action aHUS Treatment
Complement inhibition
- ECULIZUMAB:
- - Anti-C5 monoclonal antibody
- - 900 mg IV weekly x 4, then 1200 mg q2 weeks
- - Meningococcal vaccine REQUIRED
- RAVULIZUMAB:
- - Longer-acting C5 inhibitor
- - Less frequent dosing
- SUPPORTIVE:
- - Dialysis if needed
- - BP control
- - Avoid nephrotoxins
- Path rejoins step 08Shared downstream outcome
- Path rejoins step 08Shared downstream outcome
12Action Secondary TMA
Treat underlying cause
- CAUSES:
- - Drug-induced (quinine, gemcitabine, calcineurin inhibitors)
- - Malignant hypertension
- - Transplant-associated
- - Pregnancy (HELLP, preeclampsia)
- - Cancer-associated
- - Infection (HIV, COVID)
- TREATMENT: Address underlying cause
- Path rejoins step 08Shared downstream outcome
Guideline Source
ISTH Guidelines for Thrombotic Microangiopathies
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 take days
- Empiric plasma exchange often needed
- TTP vs HUS vs other TMA can be difficult
- Complement testing complex
Applicable Regions
USEU
Version 1Next review: 2027-01-11
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Frequently Asked Questions
What is the TTP/HUS Thrombotic Microangiopathy Management (ISTH 2024)?
The TTP/HUS Thrombotic Microangiopathy Management (ISTH 2024) is a emergency clinical algorithm for Nephrology. It provides a structured decision tree to guide clinical decision-making, based on ISTH Guidelines for Thrombotic Microangiopathies.
What guideline is the TTP/HUS Thrombotic Microangiopathy Management (ISTH 2024) based on?
This algorithm is based on ISTH Guidelines for Thrombotic Microangiopathies (DOI: 10.1182/bloodadvances.2020001830).
What are the limitations of the TTP/HUS Thrombotic Microangiopathy Management (ISTH 2024)?
Known limitations include: ADAMTS13 results take days; Empiric plasma exchange often needed; TTP vs HUS vs other TMA can be difficult; Complement testing complex. Individual patient factors may require deviation from these recommendations.
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