Causes
The disease is caused by spontaneous aggregation of platelets and activation of coagulation in the small blood vessels. Recently, the reason for this phenomenon has been identified to be the inhibition of an enzyme by the name of ADAMTS13 by antibodies; it is therefore an autoimmune disease. ADAMTS13 breaks down the so-called von Willebrand factor (vWF), a protein that links platelets, blood clots and the blood vessel wall in the process of blood coagulation. Very large vWF molecules are more prone to lead to coagulation.
A hereditary form of TTP is called the Shulman-Upshaw syndrome. Other rare causes are certain medications
Symptoms and signs
It is very hard to disentangle TTP from Hemolytic Uremic Syndrome (HUS). Both have very similar clinical characteristics, although the renal symptoms tend to be more outspoken in HUS. HUS is often preceded by a case of bloody diarrhea caused by the E. coli O157:H7 bacterium.
Treatment
TTP is generally treated by repeated plasmapheresis, which is the removal of the patient's blood plasma and replacement with donor's plasma.
Prognosis
Prognosis is reasonable: 90% survive an attack of TTP.
