What is idiopathic thrombocytopenic purpura?

Definition

Idiopathic thrombocytopenic purpura (ITP) is a treatable blood disorder.
Antibodies that are produced in the spleen attack and
destroy the body’s own blood-clotting cells (platelets), which help stop bleeding.
Normally, platelets move to damaged areas of the body and stick together, forming
a sort of barrier against germs. If there are not enough platelets in the body,
bleeding injuries are difficult to stop. Although people with ITP have a lower
than normal number of platelets in their blood, all other blood cell counts are normal.

There are two types of ITP. Acute ITP, which lasts less than six months and usually occurs in children, is the most common. Chronic ITP lasts more than six months and usually occurs in adults.

Causes

The cause of most cases of ITP is unknown. In children, the disorder has been
linked to viral
infections. It is believed that in these cases the immune
system becomes confused and begins attacking healthy platelet cells. When too many
platelets are destroyed, ITP can result. The disorder in adults has not been
linked to viral infections. Some cases of ITP are thought to be caused by drugs,
infection, or other immune disorders. Pregnant women too sometimes develop the
disorder.

Risk Factors

Persons with an increased chance of developing ITP include children who have had a recent viral infection or have had a live-virus vaccination (which may sometimes put a child at a higher risk); women, usually younger than age forty years; and women in general, who are two to three times more likely to get ITP than are men.

Symptoms

Both adults and children may notice the following symptoms of ITP: easy
bruising, dark urine or stools, bleeding for longer than normal following an
injury, unexplained nosebleeds, bleeding from the gums, heavier-than-normal
menstrual periods (in adult women), red dots called petechiae on the skin
(petechiae may occur in groups and resemble a rash), and, in rare cases, bleeding
within the intestinal tract or brain.

Screening and Diagnosis

A doctor will ask about symptoms and medical history and will perform a
physical exam. Tests may include a complete blood count (CBC), in which a
blood sample is tested to see if the numbers of different blood cells are normal;
and a bone marrow test, in which a needle is inserted into the skin and into the
bone and a small amount of bone marrow is removed. The sample is tested to ensure
the marrow contains normal numbers of platelet-producing cells. This test is done
to rule out other disorders. Another test is a computed tomography (CT)
scan (in rare cases). The CT scan is done if there is a
concern about bleeding in the brain.

Treatment and Therapy

Treatment for ITP is different for children and for adults. Most children
recover from ITP without any treatment. However, a doctor may recommend the
following: medications to increase platelet counts in the blood, such as
steroids (for example, prednisone), which lowers the
activity of the immune system and keeps it from destroying platelets; and gamma
globulin infusions (an antibody-containing protein that slows down platelet
destruction). An infusion means that the injection is given by IV (intravenously)
or through a shot. It usually works more quickly than steroids. Both of these
treatments work but both can have side effects. Eighty-five percent of children
who have ITP recover within a year and do not experience the problem again.

Two newer drugs stimulate platelet production: eltrombopag (Promacta) and
romiplostim (Nplate). Using these drugs and also using the targeted monoclonal
antibody rituximab (Rituxan) may prevent the need for a splenectomy. A
splenectomy is the surgical removal of the spleen. This
procedure stops the destruction of platelets because the antibodies are made in
the spleen. In adults, if drug intervention does not do enough to raise platelet
counts, the doctor may recommend a splenectomy.

A splenectomy leaves the body more vulnerable to infection from other sources. This surgery is usually not performed until medications have proven ineffective. Doctors also sometimes recommend lifestyle changes when platelet counts are low, including avoiding contact sports; patients also are recommended to wear a helmet during sports activities.

Prevention and Outcomes

Because the cause of ITP is unknown, there are no specific ways to prevent the disease. However, because bleeding and injury can be serious for people with ITP, one should take precautions to avoid injury, such as using padding on an infant’s crib or around a play area and ensuring that older children wear helmets and protective gear when playing sports (to help reduce bruising injuries). Persons with low platelet counts should stop playing contact sports.

People who have ITP should also avoid medications that contain aspirin or
ibuprofen. These medicines can reduce platelet function. To help stay healthy, one
should eat a healthful diet, low in saturated fat and rich in whole grains,
fruits, and vegetables; get regular exercise; lose weight if overweight; stop
smoking; and drink alcohol, if desired, only in moderation (two drinks per day for
men and onedrink per day for women).

Bibliography

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Bussel, J. B., et al. “Eltrombopag for the Treatment of Chronic Idiopathic Thrombocytopenic Purpura.” New England Journal of Medicine 357, no. 22 (November 29, 2007): 2237-2247.

George, J. N. “Platelets.” The Lancet 355 (April 29, 2000): 1531-1539.

George, J. N., et al. “Update on Idiopathic Thrombocytopenic Purpura.” Available at http://www.hematology.org/publications/hematologist/ 2010/4965.aspx.

Karpatkin, S. “Autoimmune (Idiopathic) Thrombocytopenic Purpura.” The Lancet 349 (1997): 1531-1536.

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Newland, A., et al. “An Open-Label, Unit Dose-Finding Study of AMG 531, a Novel Thrombopoiesis-Stimulating Peptibody, in Patients with Immune Thrombocytopenic Purpura.” British Journal of Haematology 135, no. 4 (2006): 547-553.