Health Encyclopedia

Idiopathic thrombocytopenic purpura (ITP)

Definition

Idiopathic thrombocytopenic purpura is a bleeding disorder characterized by too few platelets in the blood. This is because platelets are being destroyed by the immune system. Idiopathic means the exact cause of the disease is unknown.

Because more is being learned about the autoimmune nature of the disease, it is sometimes called immune thrombocytopenic purpura.

Alternative Names

Immune thrombocytopenic purpura; ITP

Causes, incidence, and risk factors

The disease occurs when immune system cells, called lymphocytes, produce antibodies against platelets. Platelets are necessary for normal blood clotting. They clump together to plug small holes in damaged blood vessels.

The presence of antibodies on platelets leads to their destruction in the spleen. A characteristic skin rash, easy bruising, abnormal menstrual bleeding, or sudden and severe loss of blood from the digestive tract may occur.

Usually, no other abnormal findings are present. In children, the disease sometimes follows a viral infection, and usually runs its course without treatment. In adults, it is more often a chronic (long-term) disease and can follow a viral infection, taking certain drugs, pregnancy, or other immune disorders.

ITP affects women more frequently than men, and is more common in children than adults. in Children, equal numbers of boys and girls are affected.

Symptoms

Bruising
Nosebleed or bleeding in the mouth
Bleeding into the skin - also called pinpoint red spots or petechial rash
Abnormally heavy menstruation

Signs and tests

Tests include:

Complete blood count (CBC) shows low platelet count.
Bone marrow aspiration or biopsy appears normal.
PTT is normal.
PT is normal.
Platelet associated antibodies may be detected.

Treatment

In children, the disease often runs its course without treatment.

In adults, the initial treatment is usually with a drug called prednisone. A splenectomy (removal of the spleen) is sometimes advised. The spleen is the major site of platelet destruction, but removal of the spleen will only bring up the platelet count in 50% of people.

When the disease does not respond to initial treatment, other treatments are:

Oral danazol (Danocrine)
High-dose gamma globulin (an immune factor) injections
Drugs that suppress the immune system
Passing the blood over a protein A column (Prosorba) , which filters antibodies out of the blood stream
Anti-RhD therapy can also be useful in people with specific blood types

People with ITP should avoid taking aspirin, ibuprofen, and warfarin because these drugs interfere with platelet function and blood clotting, and bleeding may occur.

Expectations (prognosis)

The chance of remission (a symptom-free period) is good with prednisone or a splenectomy. Rarely, ITP may become a chronic ailment in adults and reappear, even after remission.

Complications

Severe bleeding
Bleeding into the brain or loss of blood into the digestive tract

Calling your health care provider

Go to the emergency room or call the local emergency number (such as 911) if severe bleeding occurs, or if other new symptoms develop.

Prevention

The causes and risk factors are unknown, except in children when it may be related to a viral infection. Prevention methods are unknown.

Review Date:10/30/2006
Reviewed By:William Matsui, MD, 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.

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