What results differentiate disseminated intravascular coagulation (DIC) from thrombotic thrombocytopenic purpura (TTP)?

The differentiation between disseminated intravascular coagulation (DIC) and thrombotic thrombocytopenic purpura (TTP) is crucial in a clinical setting due to the distinct pathophysiological mechanisms and management approaches of these conditions.

In DIC, there is widespread activation of the coagulation cascade leading to the formation of fibrin clots throughout the microvasculature, which consumes platelets and coagulation factors. This consumption results in prolonged prothrombin time (PT) and activated partial thromboplastin time (aPTT) because the coagulation factors become depleted.

Conversely, in TTP, there is often a normal or mildly prolonged PT and aPTT since the coagulation factors are not consumed in the same manner as in DIC. TTP is characterized primarily by microangiopathic hemolytic anemia and thrombocytopenia without the systemic activation of the coagulation cascade that defines DIC.

Therefore, the presence of prolonged PT and aPTT helps to accurately distinguish DIC from TTP, as this indicates the consumption of clotting factors due to the activation of coagulation seen in DIC but not in TTP. In TTP, the platelet count can be low