Immune Thrombocytopenic Purpura (ITP)

What Is It?

Immune thrombocytopenic purpura (ITP), also known by the shorter name Immune Thrombocytopenia (same abbreviation 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. Platelets are produced in the bone marrow (the central lining of the bones). The body needs adequate numbers of functioning platelets to allow blood to clot and to limit bleeding if you are cut or experience other types of trauma.

• Purpura means that the illness produces a red or purple rash that is caused by bleeding under the skin. This is only one manifestation of the disease

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 patient is diagnosed with thrombocytopenia (low platelet count).

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 and brain, where it is known as an intracranial hemorrhage. Bleeding may also occur in the kidneys and bladder causing bloody urine. Excessive bleeding can also occur during normal menstrual cycles.

There are currently three classifications of ITP:

• Newly diagnosed (also referred to as acute) ITP — This form of ITP lasts for less than three 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 newly diagnosed ITP can go on to develop either persistent or chronic ITP.

• Persistent ITP: Here, the disease has been present for 3 to 12 months, and has not undergone spontaneous correction or remission on its own. It still is persistent in the face of several trials of treatment.

• Chronic ITP — This form of ITP lasts for more than 12 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 four out of every 100,000 people each year

ITP can occur during pregnancy. The low platelets can lead to serious bleeding problems both in the mother and fetus.

Symptoms

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.

Sometimes, the only symptom is the appearance of tiny purplish spots that show up on the lower legs. They are called petechiae. These are pinpoint size accumulations of blood under the skin caused by leaky small blood vessels.

At very low platelet levels, ITP can cause different symptoms, depending on the type of ITP.

• Acute ITP — Symptoms usually begin abruptly. In children, the trigger can be a viral infection, with ITP symptoms appearing one to three weeks after the infection resolves. In adults, the trigger for acute ITP may not be obvious.

  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 or person usually appears normal and active.

• Persistent or Chronic ITP — A typical patient with persistent or 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.

Diagnosis

It's important that you tell your doctor about all prescription and nonprescription drugs, natural or herbal remedies that you or your child is 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:

• A blood platelet count — Doctors always order this test first. ITP is one of the causes of a low platelet count (thrombocytopenia).

• 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.

The purpose of this test is to determine whether cells called megakaryocytes are present. Megakaryocytes are the bone marrow cells that turn into platelets.

In ITP, there should be a plenty of megakaryocytes. This indicates that the bone marrow is working normally and producing enough new platelets. And the platelets are getting out of the bone marrow into circulation. The problem is the platelets are destroyed by antibodies.

If few megakaryocytes can be seen, other diagnoses need to be entertained.

Expected Duration

Newly diagnosed (acute ITP) lasts for three months or less, with 75% of children recovering on their own within two to three months. Persistent and chronic ITP tends to come and go over many years.

Prevention

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

Treatment varies, depending on whether ITP is acute, persistent 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).

• Persistent or 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 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, the next option for adults is treatment with rituximab (Rituxan) or splenectomy (surgical removal of the spleen). Patients who have undergone spleen removal need to be aware that they are at significant increased risk for the development of certain types of infections.

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). A promising new drug called romiplostim (Nplate) may lessen the need for spleen removal. This new drug stimulates the receptors on megakaryocytes that induce these cells to make more platelets in the bone marrow.

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.

When To Call A Professional

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, lots of tiny purple spots (petechiae), frequent or heavy nosebleeds, bleeding gums or blood blisters inside the mouth or lips.

Prognosis

In children, the outlook for acute ITP is generally very good. About 75% of patients recover completely within three months, and about 80% recover within six 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 four to six 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 one week of having the spleen removed, about 70% of adult patients with chronic ITP have normal platelet counts. The risk of removing the spleen is an increased risk of infections.

External resources

National Heart, Lung and Blood Institute (NHLBI)
6701 Rockledge Drive
P.O. Box 30105
Bethesda, MD 20824-0105
Phone: (301) 592-8573
http://www.nhlbi.nih.gov/

National Institute of Allergy and Infectious Diseases (NIAID)
Building 31, Room 7A-50
31 Center Drive MSC 2520
Bethesda, MD 20892-2520
Phone: (301) 496-5717
http://www.niaid.nih.gov/

American Academy of Family Physicians (AAFP)
11400 Tomahawk Creek Parkway
Leawood, KS 66211-2672
Phone: (913) 906-6000
Toll-Free: (800) 274-2237
http://www.familydoctor.org/

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