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
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.
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.
ITP can occur in anyone at almost any age, but these factors increase your risk:
- Your sex. Women are about twice as likely to develop ITP as men are.
- Recent viral infection. Many children with ITP develop the disorder after a viral illness, such as mumps, measles or a respiratory infection.
The biggest risk associated with idiopathic thrombocytopenic purpura is bleeding, especially bleeding into the brain (intracranial hemorrhage), which can be fatal. Major bleeding is rare with ITP, however.
Complications are more likely to arise from the treatments used for chronic or severe ITP. Corticosteroids are a first line treatment because they help dampen the immune system attack on the platelets. But, long-term use of corticosteroids can cause serious side effects, including bone loss (osteoporosis), cataracts and high blood sugar levels, possibly leading to type 2 diabetes.
Removal of your spleen (splenectomy), which may be performed if corticosteroids aren't working, helps prevent the loss of platelets. However, removing the spleen also makes you permanently more vulnerable to infection. Fortunately, the risk of an overwhelming infection in a healthy person who has had a splenectomy is low.
Pregnant women with mild ITP usually have a normal pregnancy and delivery, though antibodies to platelets can cross the placenta and affect the baby's platelet count. In some cases, a baby may be born with a low number of platelets. If this happens, your baby's doctor will want to monitor your child for several days, because your baby's platelet count may drop before it starts to rise. It's likely that your baby's platelet count will improve without treatment, but if the count is very low, treatment can help the baby recover faster.
If you're pregnant and your platelet count is very low or you have bleeding, you have a greater risk of heavy bleeding during delivery. In such cases, you and your doctor may discuss treatment to maintain a stable platelet count, taking into account the effects on your baby.