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      Idiopathic Thrombocytopenic Purpura
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What Is Idiopathic Thrombocytopenic Purpura?

Idiopathic thrombocytopenic purpura (ITP) is a bleeding condition in which the blood doesn’t clot as it should. This is due to a low number of blood cells called platelets (PLATE-lets).

Platelets are also called thrombocytes (THROM-bo-sites), and they’re made in your bone marrow (along with other kinds of blood cells). Platelets circulate through the blood vessels and help stop bleeding by sticking together (clotting) to seal small cuts or breaks.

Idiopathic (id-ee-o-PATH-ick) means that the cause of the disease or condition isn’t known. Thrombocytopenic (throm-bo-cy-toe-PEE-nick) means there is a lower-than-normal number of platelets in the blood. Purpura (PURR-purr-ah) are purple bruises caused by bleeding under the skin. More extensive bleeding can create a three-dimensional mass called a hematoma (he-ma-TO-ma).


Photograph showing purpura (bruising) on the skin

The photograph show purpura (bruises) in the skin. Bleeding under the skin causes the purple, brown, and red color of the purpura.

People who have ITP often have purple bruises that appear on the skin or on the mucous membranes (for example, in the mouth). The bruises mean that bleeding has occurred in small blood vessels under the skin. A person who has ITP also may have bleeding that results in tiny red or purple dots on the skin. These dots, often seen on the lower legs, are called petechiae (peh-TEE-kee-ay). Petechiae may look like a rash.

People with ITP may have nosebleeds, bleeding from the gums when they have dental work done, or other bleeding that’s hard to stop. Women with ITP may have heavy menstrual bleeding.

Bleeding in the brain as a result of ITP is very rare, but can be life threatening if it occurs.

In most cases, the body’s immune system is thought to cause ITP. Normally your immune system helps your body fight off infections and diseases, but if you have ITP, your immune system attacks and destroys its own platelets—for an unknown reason.

Types of Idiopathic Thrombocytopenic Purpura

There are two types of ITP: acute (temporary or short-term) and chronic (long-lasting).

Acute ITP generally lasts less than 6 months. It mainly occurs in children, both boys and girls, and is the most common type of ITP. It often occurs after an infection caused by a virus.

Chronic ITP is long-lasting (6 months or longer) and mostly affects adults. However, some teenagers and even younger children can get this type of ITP. Chronic ITP affects women 2 to 3 times more often than men. Treatment depends on how severe the bleeding symptoms are and the platelet count. In mild cases, treatment may not be needed.


For most children and adults, ITP isn’t a serious or life-threatening condition.

Acute ITP in children often goes away on its own within a few weeks or months and doesn’t return. In 80 percent of children who have ITP, the platelet count returns to normal within 6 to 12 months. Treatment may not be needed. A small number of children, about 5 percent, whose ITP doesn’t go away on its own may need to have further medical or surgical treatment.

Chronic ITP will vary with each individual and can last many years. Even people who have severe forms of chronic ITP can live for decades. Most people with chronic ITP are able at some point to stop treatment and keep a safe platelet count.

August 2007

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