The underlying mechanism typically involves autoantibody-mediated inhibition of the enzyme ADAMTS13, a metalloprotease responsible for cleaving large multimers of von Willebrand factor (vWF) into smaller units. The increase in circulating multimers of vWF increases platelet adhesion to areas of endothelial injury, particularly where arterioles and capillaries meet, which in turn results in the formation of small platelet clots called thrombi. As platelets are used up in the formation of thrombi, this then leads to a decrease in the number of overall circulating platelets, which may then cause life-threatening bleeds. Red blood cells passing the microscopic clots are subjected to shear stress, which damages their membranes, leading to rupture of red blood cells within blood vessels, which in turn leads to microangiopathic hemolytic anemia and schistocyte formation. The presence of these blood clots in the small blood vessels reduces blood flow to organs resulting in cellular injury and end organ damage.
Thrombotic thrombocytopenic purpura
Atypical hemolytic uremic syndrome
Drug-induced thrombocytopenic purpura
Hemolytic–uremic syndrome
Immune thrombocytopenic purpura
Disseminated intravascular coagulation
Heparin-induced thrombocytopenia
Gray platelet syndrome