Thrombotic thrombocytopenic purpura (TTP) is a blood disorder that causes blood clots to form in small blood vessels around the body, and leads to a low platelet count (thrombocytopenia).A.D.A.M.

Causes, incidence, and risk factors

This disease may be caused by a lack of, or problems with, a certain enzyme (a type of protein) that is involved in blood clotting. These changes cause clotting to occur in an abnormal way.

• As the platelets clump together in these clots, fewer platelets are available in the blood in other parts of the body to help with clotting.
• This can lead to bleeding under the skin and purple-colored spots called purpura.

In some cases, the disorder is passed down through families (inherited) and patients are born with naturally low levels of this enzyme. This condition also may be related to:

• Bone marrow transplantation
• Cancer
• Chemotherapy
• Hematopoietic stem cell transplantation
• HIV infection
• Hormone replacement therapy and estrogens
• Medications (including ticlopidine, clopidogrel, guinine, and cyclosporine A)

Symptoms

• Bleeding into the skin or mucus membranes
• Changes in consciousness
• Confusion
• Easy fatigue
• Fever
• Headache
• Heart rate over 100 beats per minute
• Pallor
• Purplish spots in the skin produced by small bleeding vessels near the surface of the skin (purpura)
• Shortness of breath
• Speech changes
• Weakness
• Yellowish color to the skin (jaundice)

Signs and tests

• ADAMTS 13 activity level
• Bilirubin
• Blood smear
• CBC
• Creatinine level
• Lactate dehydrogenase (LDH) level
• Mucus membrane biopsy
• Platelet count
• Urinalysis
• Von Willebrand factor electropheresis

Treatment

Plasma exchange (plasmapheresis plus infusion of donor plasma) is used to remove the antibodies that are affecting clotting from the blood and also replace the missing enzyme.

• First, you will have your blood drawn as if you were donating blood.
• The plasma portion of the blood will be passed through a cell separator. The remaining portion of the blood will be saved.
• Plasma will be added to it, and the blood will be returned to you through a transfusion.

This treatment is repeated daily until blood tests show improvement.

People who do not respond to this treatment or whose condition often returns may need to:

• Have surgery to remove their spleen
• Get drugs that suppress the immune system, such as corticosteroids or rituximab

Expectations (prognosis)

Plasma exchange has greatly improved the outcome of this disease. Most patients now recover completely. However, some people die from this disease, especially if it is not found immediately. In people who don't recover, this condition can become long-term (chronic).

Complications

• Kidney failure
• Low platelet count (thrombocytopenia)
• Low red blood cell count (caused by the premature breakdown of red blood cells)
• Nervous system problems
• Severe bleeding (hemorrhage)
• Stroke

Calling your health care provider

Call your health care provider if you have any unexplained bleeding.

Prevention

Because the cause is unknown, there is no known way to prevent this condition.

References

1. McCrae KR, Sadler JE, Cines DB. Thrombotic thrombocytopenic purpura and the hemolytic uremic syndrome. In: Hoffman R, Benz EJ Jr, Shattil SJ, et al, eds. Hoffman Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingstone Elsevier;2008:chap 139.
2. Schafer A. Hemorrhagic disorders: Abnormalities of platelet and vascular function. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa:Saunders Elsevier;2007:chap 179.

Review Date: 2/28/2011.

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.