Thrombotic Thrombocytopenic Purpura

Key points

• Pathogenesis of thrombotic thrombocytopenic purpura (TTP)
• abnormally large and sticky multimers of von Willebrand's factor cause platelets to clump within vessels
• in TTP there is a deficiency of ADAMTS13 (a metalloprotease enzyme) which breakdowns large multimers of von Willebrand's factor
• overlaps with haemolytic uraemic syndrome (HUS) Features
• rare, typically adult females