How is thrombotic thrombocytopenic purpura (TTP)-hemolytic uremic syndrome (HUS) differentiated from disseminated intravascular coagulation (DIC)?

Updated: Dec 06, 2020
  • Author: Marcel M Levi, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Answer

Thrombotic thrombocytopenic purpura (TTP) – hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy superficially like DIC, but distinctly different; in contrast to DIC, the mechanism of thrombosis is not via the tissue factor (TF)/factor VIIa pathway. Results of blood coagulation assays in TTP-HUS are normal. Rather, in TTP-HUS, thrombosis arises from direct platelet activation, usually as a result of widespread endothelial damage or an inherited or acquired impairment of ADAMTS13, a protease that normally cleaves von Willebrand factor (vWF), which results in an ultralarge vWF (ULVWF) that agglutinates/activates platelets, leading to thrombosis and shearing of red blood cells on the ULVWF. [48]

TTP-HUS and DIC can usually be distinguished on the basis of their occurrence in different clinical settings (ie, trauma or sepsis for DIC and fever associated with thrombocytopenia and a microangiopathic hemolytic anemia for TTP-HUS). Patients with TTP-HUS do not demonstrate the laboratory abnormalities frequently encountered in DIC (see Workup). [49]

Other thrombotic microangiopathies include chemotherapy-induced or stem cell transplant–associated microangiopathy and HIV-induced TTP. [50]


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