What causes thrombotic thrombocytopenic purpura (TTP)?

Updated: Nov 30, 2019
  • Author: Perumal Thiagarajan, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Evidence indicates that TTP results from the abnormal presence of unusually large multimers of von Willebrand protein. [11] These ultralarge precursors, normally synthesized in the endothelial cells, are hyperactive towards platelets. These large multimers are processed by a plasma enzyme to normal-sized multimers. This enzyme is identified as ADAMTS13, a metalloproteinase synthesized in the liver. [11]

The sporadic forms of TTP are caused by an antibody or toxin inhibiting the activity of ADAMTS13. The chronic, recurrent form of TTP may result from a congenital deficiency of the enzyme.

The ultralarge multimers are thought to induce the aggregation of platelets, causing platelet consumption. Occlusion of microvasculature by the platelets in the brain, kidney, and other organs leads to myriad symptoms. A TTP-like syndrome has been associated with lupus, pregnancy, HIV infection, and certain drugs (eg, quinine, ticlopidine, clopidogrel, cyclosporine, chemotherapeutic agents).

Patients with TTP often report an episode of flulike illness 2-3 weeks before presentation. Most patients with TTP do not have the classic pentad. The most common presentation is petechiae and neurologic symptoms. The neurologic symptoms can range from headache and confusion to seizures and coma. Fever is present in slightly more than 50% of the patients.

For more information, see the Thrombotic Thrombocytopenic Purpura.

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