Thrombotic thrombocytopenic purpura

(Redirected from TTP)


  • Untreated mortality is >90%
  • Similar clinical symptoms but different pathophysiology than HUS
    • HUS more common in pediatrics
  • Microangiopathic Hemolytic Anemia (MAHA) + low Platelets is TTP until proven otherwise
    • MAHA is non-immune hemolysis (Coomb's-negative hemolysis) causing RBC fragmentation producing schistocytes
  • Can occur as a result of Plavix (clopidogrel) use, especially within the first 2 weeks


  • Insufficient ADAMTS-13 activity allows vWF multimers to accumulate in microcirculation which leads to platelet aggregation/thrombocytopenia and hemolysis of RBCs. Platelet clots are transient, but the symptoms especially neuro, can be in flux.

Risk Factors

Clinical Features

Spontaneous bruising in a woman with critically low platelets.

Pentad (rarely all present)[1]

  1. Microangiopathic Hemolytic Anemia (MAHA)
  2. Thrombocytopenia
  3. Fever
  4. Renal pathology
  5. CNS abnormalities (headache, seizure, altered mental status, CVA, coma)
    • Neuro symptoms are often transient, may not be present in ED
TTP pentad mnemonic = FAT RN
  • Fever, Anemia, Thrombocytopenia, Renal, Neuro Symptoms
  • All features DO NOT need to be present at the same time
  • Consider diagnosis without the full pentad

Differential Diagnosis

Microangiopathic Hemolytic Anemia (MAHA)


Decreased production

Increased platelet destruction or use

Drug Induced

Comparison by Etiology

↓ PLT Yes Yes Yes Yes Yes
↑PT/INR No No No +/- Yes
MAHA No Yes Yes No Yes
↓ Fibrinogen No No No No Yes
Ok to give PLT Yes No No No Yes



  • CBC with peripheral smear (anemia, microspherocytes, thrombocytopenia are suggestive findings)
    • Microangiopathic hemolytic anemia produces schistocytes
  • LDH (elevated)
  • Haptoglobin (decreased)
  • Reticulocyte count (appropriate)
  • Urinalysis (hemoglobinuria)
  • Creatinine (possibly elevated)
  • LFTs (increased bilirubin)
  • PT/PTT/INR (normal; differentiates from DIC)
  • Urine pregnancy (significant association between pregnancy and TTP)


  • Plasma ADAMTS-13 Level:
    • Ideally drawn prior to initiation of treatment, but results rarely available in the ER.
    • Level Interpretation
      • <10 IU/dL Confirms the diagnosis
      • 10-20 IU/dL Equivocal result
      • >20 IU/dL within normal, consider other diagnoses
  • PLASMIC Score: <5 features effectively rules out TTP (99% NPV)[2]
    • Platelets <30 x 109/L
    • Hemolysis with reticulocye count >2.5%, indirect bilirubin >2mg/dL, or low haptoglobin
    • MCV <90fL
    • INR <1.5
    • Creatinine <2mg/dL
    • No Current Cancer


Management ideally done in consultation with heme/onc[3]

  • Plasma exchange (plasmapheresis)
    • Replaces defective or insufficient ADAMTS-13 and clears vWF multimers
  • FFP Transfusion
    • Contains ADAMTS-13
    • Should only be initiated if delay in plasmapheresis
  • Glucocorticoids
  • Biologic Therapies: ISTH guidelines now recommend adding both empiric rituximab and caplacizumab for patients with high pretest probability while awaiting ADAMTS-13 levels.[6]
    • Rituximab is a monoclonal antibody against CD20 and is used in many autoimmune disorders
    • Caplacizumab is a monoclonal antibody blocking platelet-vWF interactions and thus formation of microvascular thrombosis.
      • Caplacizumab may be withheld in patients with whom no ADAMTS-13 can be obtained as there are concerns for increased bleeding risk with this therapy
    • In patients with low pretest probability, consider empiric plasma exchange and steroids and withhold these biologics pending ADAMTS-13 results.
  • Transfusion of pRBCs (only severe bleeding)
    • Generally only indicated if plasma exchange cannot be performed immediately
  • Splenectomy - 2nd line therapy after stabilization
    • Inhibitor antibody is made in the spleen
  • Platelet transfusion is AVOIDED
    • Only used for life-threatening bleeding or intracranial hemorrhage under guidance from hematologist
    • Platelet infusion may lead to acutely worsened thrombosis, renal failure, and death


  • Admit for plasma exchange

See Also


  1. George J: Clinical practice. Thrombotic thrombocytopenic purpura. N Engl J Med 2006; 354:1927
  2. Paydary K, Banwell E, Tong J, Chen Y, Cuker A. Diagnostic accuracy of the PLASMIC score in patients with suspected thrombotic thrombocytopenic purpura: A systematic review and meta-analysis. Transfusion. 2020 Sep;60(9):2047-2057. doi: 10.1111/trf.15954. Epub 2020 Aug 5. PMID: 32757237.
  3. George J. How I treat patients with thrombotic thrombocytopenic purpura: 2010. Blood 2010; 116:4060
  4. Bell WR, Braine HG, Ness PM, Kickler TS. Improved survival in thrombotic thrombocytopenic purpura-hemolytic uremic syndrome. Clinical experience in 108 patients. N Engl J Med 1991; 325:398.
  5. Balduini CL, Gugliotta L, Luppi M, et al. High versus standard dose methylprednisolone in the acute phase of idiopathic thrombotic thrombocytopenic purpura: a randomized study. Ann Hematol 2010; 89:591.
  6. Zheng XL, Vesely SK, Cataland SR, Coppo P, Geldziler B, Iorio A, Matsumoto M, Mustafa RA, Pai M, Rock G, Russell L, Tarawneh R, Valdes J, Peyvandi F. ISTH guidelines for treatment of thrombotic thrombocytopenic purpura. J Thromb Haemost. 2020 Oct;18(10):2496-2502. doi: 10.1111/jth.15010. Epub 2020 Sep 11. PMID: 32914526; PMCID: PMC8091490.