About blood disorders Information on blood disorders TTP (Thrombotic Thrombocytopenic Purpura) TTP is a rare blood disorder where small blood clots (microthrombi) develop in blood vessels anywhere in the body – this is the ‘thrombotic’ part of the condition. ’Thrombocytopenic’ relates to an increased need for platelets (blood cell fragments needed for blood clotting) causing a deficiency which then leads to bleeding problems which is ‘purpura’, the purplish bruising which occurs just under the skin. The underlying cause is unknown, however TTP appears to be due to damage to the inner lining of blood vessels and the high circulation of von Willebrand factor (vWF). vWF are proteins which are involved in blood clotting and platelet function. High levels of vWF accumulate when there is an absence of the enzyme ADAMTS13, which is responsible for the cleaving or degradation of vWF. To date, ADAMTS13 is the only specific biological marker able to predict TTP relapses during the follow-up in clinical remission. There are ADAMTS13 tests available, however the testing protocols currently being implemented internationally vary. Perth Blood Institute and our team at Murdoch University are involved in a study to develop a universal testing standard to diagnose TTP quickly, as early detection and accurate classification of people with TTP is crucial. Time is everything in regard to the formation of microthrombi, which can lead to organ damage and death. To read about what it's like living with TTP, visit Sam's story. For additional information about TTP please read our information leaflet.