Thrombotic thrombocytopenic purpura
Thrombotic thrombocytopenic purpura (TTP) is a blood disorder that causes blood clots to form in small blood vessels. This leads to a low platelet count (thrombocytopenia).
This disease may be caused by problems with an 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.
- The blood clots prevent oxygen from reaching these parts of the body.
In some cases, the disorder is passed down through families (inherited). In these cases, people are born with naturally low levels of this enzyme. This condition also may be caused by:
- Hematopoietic stem cell transplantation
- HIV infection
- Hormone replacement therapy and estrogens
- Medicines (including ticlopidine, clopidogrel, guinine, and cyclosporine A)
Symptoms may include any of the following:
- Bleeding into the skin or mucus membranes
- Fatigue, weakness
- Pale skin color or yellowish skin color
- Shortness of breath
- Fast heart rate (over 100 beats per minute)
Exams and Tests
Tests that may be ordered include:
- ADAMTS 13 activity level
- Blood smear
- Creatinine level
- Lactate dehydrogenase (LDH) level
- Mucus membrane biopsy
- Platelet count
- Von Willebrand factor assay
You may have a treatment called plasma exchange. It removes your abnormal plasma and replaces it with normal plasma from a healthy donor. Plasma is the liquid part of blood that contains blood cells and platelets. Plasma exchange also replaces the missing enzyme.
The procedure is done as follows:
- First, you have your blood drawn as if donating blood.
- As the blood is passed through a machine that separates blood into its different parts, the abnormal plasma is removed and your blood cells are saved.
- Your blood cells are then combined with normal plasma from a donor, and then given back to you.
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 medicines that suppress the immune system, such as steroids or rituximab
Most people who undergo plasma exchange recover completely. But some people die of this disease, especially if it is not diagnosed right away. In people who do not recover, this condition can become long-term (chronic).
Complications may include:
- 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)
When to Contact a Medical Professional
Call your health care provider if you have any unexplained bleeding.
Because the cause is unknown, there is no known way to prevent this condition.
McCrae KR, Sadler JE, Cines DB. Thrombotic thrombocytopenic purpura and the hemolytic uremic syndrome. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, Anastasi J, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 136.