TTP is caused by a deficiency of a normal blood enzyme that is named ADAMTS13 (you don’t need to know why it has this name). To cause TTP, ADAMTS13 must be absent or severely deficient.  We usually describe a severe deficiency as less than 10% of the normal levels.  Levels above 10% seem to be enough. ADAMTS13 acts to prevent platelet clumping in the circulation of small blood vessels.  ADAMTS13 is needed to trim a very long protein of the blood, that is named von Willebrand factor, abbreviated as VWF (it’s named after a person, you don’t need to know that either).  VWF is an extremely long string of a protein, and this is how it catches and clumps platelets. If there is no ADAMTS13 in the blood, these extremely long strings persist and platelet clumping can occur where it shouldn’t occur, in the normal circulation in a normal blood vessel.  If ADAMTS13 is present, it trims these long strings down to their normal size.  Normal size VWF can still effectively clump platelets, but only when there is a cut or trauma or damage to the blood vessel and blood clotting with platelet clumping needs to occur.  The absence of ADAMTS13 doesn’t mean that platelets are going to clump and block blood vessels all the time, every day, causing constant TTP.  The absence of ADAMTS13 only means that a person is vulnerable to the platelet clumping and the disorder we call TTP when some stress occurs.  The stress can be any illness (like influenza), or surgery, or pregnancy.  In most patients we don’t know what the stress or the “trigger event” is.

ADAMTS13 deficiency can be inherited or acquired. 

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What is the treatment for TTP?

What is the frequency of TTP?

What happens following recovery from an episode of TTP?



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