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 (https://www.mdcalc.com/plasmic-score-ttp)

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 (below)!

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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