Thrombotic thrombocytopenic purpura

Definition

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).

See also: Hemolytic-uremic syndrome

Alternative Names

TTP

Causes, incidence, and risk factors

This disease may be caused by the lack of an enzyme (a type of protein) that is involved in blood clotting. Not having enough of this enzyme causes clotting to occur. 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 many cases, the disorder is passed down through families (inherited). The condition also may be related to:

• Bone marrow transplantation
• Cancer
• Chemotherapy
• HIV infection
• Hormone replacement therapy and estrogens
• Many commonly used medications (including ticlopidine, clopidogrel, 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 on exertion
• Speech changes
• Weakness
• Yellowish color to the skin (jaundice)

Signs and tests

• Bilirubin
• Blood smear
• CBC
• Creatinine level
• Lactate dehydrogenase (LDH) level
• Mucus membrane biopsy
• Platelet count
• Urinalysis

Treatment

Plasma exchange (plasmapheresis) is used to remove the abnormal antibody from the blood and 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 who have frequent recurrences, may need to have surgery to remove their spleen. Or, they may need to get drugs that suppress the immune system (such as corticosteroids).

Expectations (prognosis)

Plasma exchange has improved the outcome of this disease. Most patients now recover completely. However, some people can 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

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.