Answer
• Damage to endothelial cells by the TOXIN is the primary event in the pathogenesis of hemolytic-uremic syndrome → narrowed lumen, thrombus, expanded subendothelial zone (TMA capillary)
• Pathology: the cardinal lesion is composed of arteriolar and capillary microthrombi (thrombotic microangiopathy [TMA]) and red blood cell (RBC) fragmentation
• Kidney: affects glomerular capillaries and small arterioles
• Can occur in other organ capillaries