Thrombotic thrombocytopenic purpura (TTP) is characterized by which of the following?

Thrombotic thrombocytopenic purpura (TTP) is a serious blood disorder characterized by the formation of small blood clots (thrombi) throughout the body's small blood vessels. One of the hallmark features of TTP is increased platelet aggregation. This occurs due to the presence of unusually large von Willebrand factor multimers, which promote platelet adhesion and aggregation, leading to excessive clot formation.

In the context of TTP, the excessive activation of platelets leads to the consumption of available platelets, resulting in thrombocytopenia (low platelet count). The increased aggregation is part of the pathophysiological process that causes microangiopathic hemolytic anemia and organ dysfunction associated with this condition.

The other choices do not accurately describe TTP. Prolonged PT (prothrombin time) and prolonged APTT (activated partial thromboplastin time) typically suggest deficiencies in coagulation factors or anticoagulation therapy, which are not characteristic of TTP. Thrombocytosis (increased platelet count) is also not associated with TTP since the disease is defined by a significantly low platelet count due to consumption in the microvasculature.