Thrombotic thrombocytopenic purpura (TTP) is a rare disorder causing extensive microscopic thromboses to form in small blood vessels throughout the body.Most cases of TTP arise from inhibition of the enzyme ADAMTS13, a metalloprotease responsible for cleaving large multimers of von Willebrand factor (vWF) into smaller units. A rare form of TTP, called Upshaw-Schülman syndrome, is genetically inherited as a dysfunction of ADAMTS13.The incidence of TTP is about 4-6 per million people per year.Due to the high mortality of untreated TTP, a presumptive diagnosis of TTP is made even when only microangiopathic hemolytic anemia and thrombocytopenia is seen, and therapy is started.Since the early 1990s, plasmapheresis has become the treatment of choice for TTP. Most patients with refractory or relapsing TTP receive additional immunosuppressive therapy,The mortality rate is approximately 95% for untreated cases, but the prognosis is reasonably favorable (80-90%) for patients with idiopathic TTP diagnosed and treated early with plasmapheresis.