Case of the Month #19 - TTP

Published 01/02/2022

How do you distinguish between Disseminated Intravascular Coagulation, HUS, and TTP?

  DIC HUS TTP
Blood pressure normal or   Normal
Thrombocytopaenia +++ ++ +++
Coagulation profile PT, aPTT,
FDPs,
fibrinogen		 normal normal
Haemolysis + +++ +++
Blood film schistocytes schistocytes schistocytes
Renal impairment ++ +++ ++
Other organ dysfunction systemic/multi-organ failure renal neurological renal
ADAMTS13 activity >10% >10% <5-10%
STEC stool culture or PCR   + (but can be negative in atypical HUS)  

 

It can be challenging to differentiate DIC, TTP, and HUS due to overlapping signs and symptoms.  An important factor in distinguishing DIC from TTP and HUS is the coagulation profile which is likely to show prolonged PT and aPTT, elevated fibrin degradation products, and low fibrinogen levels in DIC.  Whereas, the coagulation profile is generally normal in HUS and TTP1.

In contrast, patients with HUS are usually hypertensive and are more likely to have significant acute renal dysfunction requiring renal replacement therapy compared to patients with TTP.  STEC is strongly associated with HUS2.

ADAMTS13 activity is significantly reduced in TTP.