Immune thrombocytopenic purpura (ITP) can be understood by looking at the three terms that make up its name:

• Immune indicates that the illness is caused by the immune system, which makes cells and antibodies that attack the person's own platelets – the parts of the blood that help the blood to clot.
• Thrombocytopenic means that the illness is related to low levels of thrombocytes, another name for platelets.
• Purpura means that the illness produces a red or purple rash that is caused by bleeding under the skin.

In short, ITP is an illness in which unusually low levels of platelets lead to purpura and other forms of abnormal bleeding.

In people with ITP, the immune system produces abnormal proteins called antiplatelet antibodies. These misdirected proteins attach themselves to the surface of blood platelets as if the platelets were "foreign" or invading bacteria or viruses. As the affected platelets circulate in the bloodstream, they are recognized as abnormal by the spleen and removed from the blood. As more and more platelets are removed by the spleen, the level of platelets in the blood drops past the lower limit of normal (about 130,000 per cubic millimeter of blood) and the person is diagnosed with thrombocytopenia. When platelet levels fall into the 30,000 to 50,000 range, a person may begin to have abnormal bleeding after a minor skin injury, such as a small cut, bruise, medical injection, blood test or tooth extraction. If platelet levels fall below 10,000, the person has an increased risk of bleeding, even when no injury has occurred. This type of bleeding is especially dangerous if it happens inside the skull, where it is known as an intracranial hemorrhage.

There are two types of ITP: acute and chronic.

• Acute ITP – This form of ITP lasts for less than six months and typically affects children, most commonly those between the ages of 2 and 6. It usually appears shortly after a viral infection. Most children with acute ITP recover without treatment, and their platelet counts eventually rise to normal levels. However, 7% to 28% of people with acute ITP go on to develop chronic ITP.



• Chronic ITP – This form of ITP lasts for more than six months, usually strikes adults between the ages of 20 and 40, and requires medical treatment to restore normal platelet levels. Chronic ITP is three times more common in women than men. Typically, a person has weeks or months of mild to moderate abnormal bleeding off and on before seeing a doctor.

In most cases, the cause of ITP is unknown. In a few cases, ITP can be a reaction to a specific drug or food ingredient, such as quinine in tonic water. In the United States, ITP is a relatively rare illness that affects about 4 of every 100,000 people each year.

ITP does not cause symptoms as long as your platelet count remains above 50,000, which usually is the minimum needed to prevent abnormal bleeding. At lower platelet levels, ITP can cause different symptoms, depending on the type of ITP:

• Acute ITP – Symptoms usually begin abruptly, often one to three weeks after a child has had a viral infection. The first sign of the illness may be a red or purple skin rash on the legs or abnormal bruising after only minor trauma. There also may be small areas of bleeding or "blood blisters" on the surface of the lips or gums, and frequent or severe nosebleeds. Except for these symptoms, the child usually appears normal and active.



• Chronic ITP – A typical patient with chronic ITP is an adult woman who has had intermittent episodes of unexplained bruises, cuts that tend to heal slowly and ooze blood, prolonged bleeding after tooth extractions, and unusually long or heavy menstrual periods. Occasionally, an adult with chronic ITP will have symptoms appear suddenly, as occurs in children with acute ITP.

It's important that you tell your doctor about all prescription and nonprescription drugs, natural or herbal remedies that you or your child are taking. Your doctor will examine you or your child with special attention to any rashes, areas of bruising, oozing cuts or other signs of abnormal bleeding. Your doctor will order one or more of the following tests:

• Blood tests – Several different blood tests may be done, including a test for the presence of antiplatelet antibodies.
• A blood smear – In this test, a drop of blood is smeared on a glass slide so that the size, shape and general appearance of the platelets and other blood cells can be checked under a microscope.

Depending on the results of these tests, a bone marrow biopsy may be necessary, especially if the patient is a child who has not had an infection recently or an adult who has had abnormal bleeding on and off for a long time. In a bone marrow biopsy, a small piece of bone marrow is removed and examined in a laboratory.

Acute ITP lasts for six months or less, with 75% of children recovering on their own within two to three months. Chronic ITP tends to come and go over many years.

There is no way to prevent ITP. If a substance has caused the condition, you or your child will be told to avoid the substance.

Treatment varies, depending on whether ITP is acute or chronic:

• Acute ITP – Because most children with acute ITP recover without treatment, doctors usually do not prescribe medications unless there is serious bleeding or the platelet count falls below 20,000. If this happens, the child is treated with prednisone (a synthetic steroid sold under several brand names) by mouth and gamma globulin or anti-Rho(D) immune globulin (WinRho) given intravenously (into a vein).



• Chronic ITP – An adult with chronic ITP is treated either when the platelet count falls below 20,000 or when the platelet count falls below 50,000 and there is active bleeding. Adult treatment usually begins with oral prednisone. If prednisone does not keep the platelet count above 50,000, or the dose of prednisone needs to remain high, then doctors most often order intravenous gamma globulin or anti-Rho(D) immune globulin. If this is not effective, then the spleen may need to be removed surgically. Other drugs that are prescribed to maintain an adequate platelet count include danazol (Danocrine), azathioprine (Imuran), cyclophosphamide (Cytoxan, Neosar), vincristine (Oncovin and others) and vinblastine (Velban).

All medications, foods and beverages will be reviewed to be certain that they do not contain an ingredient that may have triggered the ITP. For example, in certain people, ingesting quinine can cause a low platelet count.

During treatment for ITP, you or your child will be advised to avoid sports and other physical activities that have a high risk of injury, especially head injury.

Call your doctor if you have had episodes of abnormal bleeding, including easy bruising, prolonged oozing from small cuts, abnormal menstrual bleeding, or prolonged bleeding after minor surgery or dental procedures.

If you are a parent, call your pediatrician or family doctor if your child develops signs of abnormal bleeding, such as easy bruising, a red or purple rash, frequent or heavy nosebleeds, bleeding gums, or blood blisters inside the mouth or lips.

In children, the outlook for acute ITP is generally very good. About 75% of patients recover completely within 3 months, and about 80% recover within 6 months. Less than 1% of children with ITP develop bleeding within the skull. Only a small percentage of children go on to develop chronic ITP, and most of these children do not have serious bleeding.

Symptoms of chronic ITP usually come and go in adults. When medication is necessary, about 50% of patients who are treated with prednisone have normal platelet counts within 4 to 6 weeks. However, when the prednisone is reduced, the platelet count drops again in many people. If this happens, doctors may recommend that the person's spleen be removed. Within 1 week of having the spleen removed, about 70% of adult patients with chronic ITP have normal platelet counts.

National Heart, Lung, and Blood Institute (NHLBI)
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National Institute of Allergy and Infectious Diseases (NIAID)
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American Academy of Family Physicians (AAFP)
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