Episode 018: Heme/Onc Emergencies, Pt. 7: TTP

Emergencies happen in hematology and oncology. This is a fact. But how do we manage these emergencies? Look no further.

In this episode, we talk all about our fourth hematologic emergency:thrombotic thrombocytopenic purpura (TTP)


Thrombotic thrombocytopenic purpura (TTP):

  • Be sure to check out episode 009 on thrombocytopenia for a general approach and differential!

  • New anemia and thrombocytopenia should raise concerns for TTP!

  • Workup:

    • Peripheral smear - concern for schistocytes. Look at this first! Example of these cells from ASH image bank here

    • ADAMTS13 level - always draw ASAP before any intervention

    • Repeat CBC

    • Reticulocyte count - will have elevated retic count

    • Citrated platelet count

    • CMP

    • PT, PTT, INR

    • Fibrinogen

    • Haptoglobin

    • LDH

    • Viral serologies

  • Clinical manifestations:

    • Fever, Anemia, Thrombocytopenia, Renal (AKI), Altered Mental Status

    • If you see this - the patient is in bad shape

  • Mechanism:

    • Tiny blood clots form in the body, causing platelet shearing

    • Loss of ADAMTS13 -

      • This protein normally is responsible for chopping up von Willebrand’s factor (vWF)

      • In the absence of ADAMTS13, vWF multimers are extra long, therefore interacting with platelets/collagen more and causing activation of platelets and clotting system

      • This causes red blood cell shearing due to small vessel microthrombi (brain, kidneys, heart)

      • Cytokine release causes fevers

  • Management:

    • Do not reflexively transfuse platelets; can make situation worse

    • PLASMIC Score: helps to stratify likelihood of TTP; MDCalc link

    • Treatment:

      • Plasma exchange: replacing ADATMS13-deficient plasma with ADAMTS13-rich plasma

        • This is different than plasmapheresis, where we replace plasma with albumin

      • Steroids: 1mg/kg prednisone daily to stop auto-antibody (against ADAMTS13) production

      • Confirm with ADAMTS13 levels; if <10%, this is confirmatory. This is why this is the FIRST step that we just send off as soon as TTP is suspected

      • IF YOU DON’T HAVE ACCESS TO PLASMA EXCHANGE: can administer FFP until you can get them to a center than can do plasma exchange

      • Caplacizumab: reserved for patients with severe neurological dysfunction, stroke, or myocardial infarction. Check out the NEJM paper on this!

Microangioathic hemolytic anemia (MAHA):

  • Umbrella term for red blood cells shearing in the small blood vessels; TTP is one example of a MAHA

    References:

https://ashpublications.org/blood/article/129/21/2836/36273/Thrombotic-thrombocytopenic-purpura - great review article from ASH on TTP

https://www.nejm.org/doi/10.1056/NEJMoa1806311 - NEJM paper on caplacizumab


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Episode 019: Heme/Onc Emergencies, Pt. 8: APL

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Episode 017: Heme/Onc Emergencies, Pt. 6: Heparin-Induced Thrombocytopenia (HIT)