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 (nervous system) abnormalities. A similar condition is hemolytic-uremic syndrome.

Blood cells

Alternative Names

Causes, incidence, and risk factors

In some cases, this disease is caused by a deficiency in an enzyme (a type of protein) called the von Willebrand Factor cleaving protease (also called ADAMTS13). Loss of this enzyme results in large complexes of von Willebrand 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 Willebrand 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 Blood is withdrawn from the patient as for a blood donation.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 80-90% of patients now recover completely. However, fatalities still occur. With relapses, the remaining cases become chronic (long-term).

Complications

• Kidney failure
• Hemorrhage
• Stroke

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.

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Review Date:7/29/2005
Reviewed By: William Matsui, M.D., Assistant Professor of Oncology, Division of Hematologic Malignancies, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD. Review provided by VeriMed Healthcare Network.