Idiopathic thrombocytopenic purpura (ITP)

DEFINITION

Idiopathic thrombocytopenic purpura (ITP) is a disorder that can lead to easy or excessive bruising and bleeding. The bleeding results from unusually low levels of platelets — the cells that help your blood clot.

Idiopathic thrombocytopenic purpura, which is also called immune thrombocytopenic purpura, affects both children and adults. Children often develop idiopathic thrombocytopenic purpura after a viral infection and usually recover fully without treatment. In adults, however, the disorder is often chronic.

Treatment of idiopathic thrombocytopenic purpura depends on your symptoms, your platelet count and your age. If you don’t have signs of bleeding and your platelet count isn’t too low, treatment for idiopathic thrombocytopenic purpura usually isn’t necessary. More serious cases may be treated with medications or, in critical situations, with surgery.

CAUSES

The exact cause of ITP isn’t known. That’s why it’s referred to as idiopathic, which means “of unknown cause.” It is known, however, that in people with idiopathic thrombocytopenic purpura, the immune system malfunctions and begins attacking platelets as if they were foreign substances.

Antibodies produced by your immune system attach themselves to the platelets, marking the platelets for destruction. The spleen, which helps your body fight infection, recognizes the antibodies and removes the platelets from your system. The result of this case of mistaken identity is a lower number of circulating platelets than is normal.

A normal platelet count is generally higher than 150,000 platelets per microliter of circulating blood. People with ITP often have platelet counts below 20,000. As the number of platelets decreases, your risk of bleeding increases. The greatest risk is when your platelet count falls very low — below 10,000 platelets per microliter. At this point, internal bleeding may occur despite a lack of any injury.

In most children with ITP, the disorder follows a viral illness, such as the mumps or the flu. It may be that an infection sets off the immune system, triggering it to malfunction.

SYMPTOMS

Idiopathic thrombocytopenic purpura (ITP) may have no symptoms. When signs and symptoms do occur, they may include:

• Easy or excessive bruising (purpura) — your skin naturally bruises and bleeds more easily as you age, but this shouldn’t be confused with ITP
• Superficial bleeding into your skin that appears as a rash of pinpoint-sized reddish-purple spots (petechiae), usually on your lower legs
• Prolonged bleeding from cuts
• Spontaneous bleeding from nose
• Bleeding gums, especially after dental work
• Blood in urine or stools
• Unusually heavy menstrual flow
• Fatigue

When to see a doctor

If you or your child has abnormal bleeding or bruising, or develops a rash of pinpoint-sized red spots, see your doctor. It’s also important to seek medical advice if you’re a woman who suddenly develops significantly increased menstrual bleeding, as this may be a sign of ITP.

Serious or widespread bleeding indicates an emergency and requires immediate care.