TTP

Alternative names
Thrombotic thrombocytopenic purpura

Definition
TTP is a blood disorder characterized by low platelets, low red blood cell count (caused by premature breakdown of the cells), abnormalities in kidney function, and neurological abnormalities. A similar clinical condition with overlapping features is hemolytic-uremic syndrome.

Causes, incidence, and risk factors

This disease is caused by a deficiency in the von Willebrand Factor cleaving protease, known as ADAMTS13. The loss of this enzyme results in large complexes of von Willbrand factor circulating in the blood, which in turn causes platelet clumping and red blood cell destruction.

Although most cases have no known cause, some cases may be related to a deficiency of ADAMTS13 at birth, cancer, chemotherapy, HIV infection, hormone replacement therapy and estrogens, and a number of medications in common use (including ticlopidine, clopidogrel, and cyclosporine A).

Symptoms

     
  • Fever  
  • Weakness  
  • Easy fatigue  
  • Pallor  
  • Shortness of breath on exertion  
  • Heart rate over 100 per minute  
  • Purpura - purplish discolorations in the skin produced by small bleeding vessels near the surface of the skin  
  • Bleeding into the skin or mucus membranes  
  • headache  
  • Confusion  
  • Speech changes  
  • Alterations in consciousness  
  • Yellowish color to the skin (jaundice)

Signs and tests

     
  • Platelet count is low  
  • CBC shows anemia  
  • Bilirubin is high  
  • Blood smear shows schistocytes and fragmented blood cells  
  • Urinalysis shows protein or microscopic blood particles  
  • Creatinine level is high  
  • Mucus membrane biopsy reveals platelet clots in small blood vessels

Treatment

Plasmapheresis, or plasma exchange, is used to remove unwanted substances from the blood (large von Willebran protein complexes), and to replace the missing protease. Blood is withdrawn from the patient as for a blood donation.

Then the plasma portion of the blood is passed through a cell separator. The remaining portion of the blood is saved, reconstituted with fresh plasma, and returned to the patient as a blood transfusion.

In thrombotic thrombocytopenic purpura, this treatment is repeated daily until blood tests show improvement. People who do not respond to this treatment, or have frequent recurrences, may require the removal of the spleen, corticosteroids, or other immune suppression.

Expectations (prognosis)
Plasmapheresis has improved the outcome of this disease so that 80 to 90% of patients now recover completely. However, fatalities still occur. With relapses, the remaining cases become chronic (long-term).

Complications

Calling your health care provider
Call your health care provider if unusual or unexplained bleeding occurs.

Prevention
Because the specific cause is unknown, specific prevention is also unknown.

Johns Hopkins patient information

Last revised: December 3, 2012
by Levon Ter-Markosyan, D.M.D.

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