2 learning resources available for this topic
Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) represents a spectrum of thrombotic microangiopathies characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ dysfunction. These conditions involve widespread formation of platelet-rich microthrombi in small vessels, leading to mechanical destruction of red blood cells and consumption of platelets.
TTP is primarily caused by severe deficiency of ADAMTS13, a metalloprotease that cleaves von Willebrand factor multimers, leading to accumulation of ultra-large vWF multimers and excessive platelet aggregation. HUS typically results from Shiga toxin-producing bacteria (especially E. coli O157:H7) that damage glomerular endothelium, or from complement dysregulation in atypical HUS, causing localized thrombotic microangiopathy primarily affecting the kidneys.
The classic pentad of TTP includes thrombocytopenia, microangiopathic hemolytic anemia, neurological symptoms, fever, and renal dysfunction, though all five features are present in less than 40% of cases. HUS predominantly presents with the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, with neurological involvement being less common. Prompt recognition and differentiation between TTP and HUS is crucial as treatment approaches differ significantly, with TTP requiring urgent plasma exchange therapy.