Tasty Morsels of EM 070 – TTP

12 Jun

Thrombotic Thrombocytopaenic Purpura or TTP, cause who has time for that…

This is something that I’ve heard talks and podcasts on multiple times but it just doesn’t seem to stick. We had a talk at a training day and while at least I spotted it during the case presentation I still was unsure, hence I’m writing it down in the hope I remember it.

This is a rare haematological condition with an almost 100% mortality without treatment but does really quite well of managed appropriately.

For us in ED it’s all about recognising it as a potential differential.

It’s a disease of microthrombi formation (platelets are low from consumption) which causes the end organ damage and haemolysis as the red cells get damaged squeezing past the microthrombi. There’s something called ADAMSTS13 that does something to von willebrand’s factor but honestly i couldn’t follow it and couldn’t see the relevance to what we do…

Presentation

  • often some neuro involvement, agitation, confusion, possibly seizures
  • frequently a rash – some kind of petechia or purpura, nothing especially specific
  • bulb should come when the lab results come back:
    • on the FBC look for anaemia and low platelets (often very low, below 20)
    •  the key is to ask for a blood film. A good lab tech will do this automatically but we need to think of it too and ask them to do it needed. The key finding is schistocytes or in some labs they call them fragmented red cells (much more descriptive but introduces confusion as now I’ve two terms to remember…)
    • this finding on the blood film suggests MAHA (not Baja…) Mircoangiopathic Haemolytic Anaemia
  • once you’ve got this far there’s probably a few further tests to consider
    • remember MAHA means haemolytic so expect a raised bili
    • the other two to consider are LDH (haematology favourite test) which is often very high. Reticulocytes is the other one – these are baby blood cells and a high level suggest the marrow is working over time to replace losses in this case from haemolysis
  • there’s often some aki too as the microthrombi damage the kidneys

There is a “classic” Pentad which means if you depend on it you’ll probably never diagnose it like Becks, no not that Beck, this Beck

For us, more realistically, we should consider this when we have someone a bit sick with some funny blood results

  • anemia
  • low platelets
  • maybe an AKI

The next step is to think blood film and look for schistocytes or fragmented blood cells (the same thing remember) and ring haematology.

Treatment is plasma exchange which is not as yet an ED work place based assessment as far as I’m aware so you’re going to need help

The other important thing is not to give platelets. Basically it’s fuel for the fire of microthrombi formation so unless they’re bleeding out the wazoo then hold off

Further Reading

  • I once heard a Weingart podcast on this but I can’t find it- I just know it was good…
  • There’s a great EMDOCS blog that is a must read

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