There is a big difference between ITP and TTP. Usually with TTP, the red cells are also affected and might be low on a CBC. The symptoms would be more severe than with ITP, such as low platelets, low red cells and the accompanying symptoms of both, neurological symptoms and possibly kidney/renal involvement, fever, seizures, coma, stroke, etc. People who have it usually don't just walk around with it, they are usually admitted to the hospital with severe symptoms. Treatment for TTP is also different than ITP and usually won't respond to ITP treatments. TTP is treated with plasmapheresis (filtering of the blood) and other methods.
"Thrombotic Thrombocytopenic Purpura is a rare autoimmune blood disorder that is considered a true medical emergency. TTP is diagnosed at a rate of 3-4 in 1 million people per year. Potentially fatal complications can result from internal blood clotting with damage to critical organs such as the brain, heart and kidneys.
The cause of TTP continues to evade us. What is known is that blood becomes "sticky" and forms clots in blood vessels throughout the body. These clots are made up of platelets, one of the elements in blood. Vital blood flow to the body's organs is restricted, placing the organs at risk for damage due to a lack of oxygen and nutrients from the blood."
Known Triggers
There is still much to learn about the mechanism that causes TTP. But it has been generally accepted that the following may trigger an episode;
Pregnancy
Cancer
Infections and live vaccines
Underlying autoimmune conditions such as Lupus
Medical procedures, surgery and blood and marrow stem cell transplant and pancreatitis
Medicines such as quinine, chemotherapy, ticlopidine, clopidogrel, cyclosporine A, hormone replacement therapy and estrogens
www.answeringttp.org/ttp-overview