Thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura, known as TTP, is a blood disorder in which clots form in small blood vessels throughout the body, lowering platelet counts, breaking down red blood cells and risking dysfunction of the kidneys, heart and brain. Patients typically experience bruising, fever, weakness, breathing difficulty, confusion and headaches; the classic combination of fever, altered mental status, low platelets, kidney impairment and hemolytic anemia occurs in fewer than ten percent of cases. The underlying mechanism is autoantibody mediated inhibition of the enzyme ADAMTS13, which normally breaks down large von Willebrand factor molecules; without enough ADAMTS13 activity these oversized molecules accumulate and trigger excessive platelet clumping in small vessels, damaging tissue. About half of cases have an identifiable trigger, including bacterial infection, certain medications, autoimmune conditions such as lupus, or pregnancy, while the rest are of unknown origin. A rarer inherited form, caused by congenital ADAMTS13 deficiency, is known as Upshaw-Schulman syndrome.