 Idiopathic Thrombocytopenia Purpura
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Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder that causes the body to destroy its platelets, the blood cells necessary to control bleeding. People with ITP develop bruising, bleeding into the skin (petechiae) and often bleeding from mucous membranes such as the nose and mouth. A rare but serious complication of ITP is bleeding into the head. This is usually prompted by some type of trauma to the head.
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- Idiopathic means occuring for no known cause.
- Thrombocytopenia means a decreased number of platelets in the blood.
- Purpura refers to the purple discoloring of the skin, as with a bruise.
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ITP affects approximately 3,000 children under the age of 16 each year in the U.S. There are two forms of ITP:
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- Acute thrombocytopenic purpura - most commonly seen in children 2 to 6 years old. The symptoms may follow a viral illness, such as chickenpox. Acute ITP usually has a very sudden onset and the symptoms usually disappear in less than six months (often within a few weeks). The disorder usually does not recur. Acute ITP is the most common form of the disorder. The risk of serious or life-threatening bleeding is very low.
- Chronic thrombocytopenic purpura - the onset of the disorder can happen at any age, and the symptoms last a minimum of six months and can persist for many years. Chronic ITP is more common in adults, but can affect young children and adolescents. Females have it two to three times more often than males. Chronic ITP may become a life-long problem and regular follow up care with a blood specialist (hematologist) is recommended.
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The bone marrow is the soft, spongy center of the long bones and is home to the stem cells that are responsible for making blood cells, including platelets. The bone marrow responds to the low number of platelets and produces many more to send out to the body. In a child with ITP, many young platelets are present, but tests of circulating blood show very low numbers of platelets. The body is producing the cells normally, but it is also destroying them. In most cases, other blood tests are normal. In people with ITP, the platelets usually survive only a few hours, instead of the normal 7 to 10 days.
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In most cases, the cause of ITP is unknown. The illness is not contagious, meaning a child cannot "catch it" from playing with another child with ITP. It is important to know that nothing the parents or the child did caused the disorder.
In ITP, the body produces antibodies that stick to platelet cells. Normal antibodies are proteins that guard against infection. The spleen, an organ that is responsible for removing disease-causing cells from the body, recognizes the antibodies as signs of foreign cells and destroys the platelets to which they are attached.
Often, a child with ITP may have had a viral infection a few weeks before developing evidence of ITP. Viral infections may trigger ITP. While making antibodies to the virus, the body may make abnormal antibodies that lead to platelet destruction.
Researchers have explored the possibility that certain medications cause ITP. While we know that some medications can alter platelet function, no direct link has been made to any specific medication and ITP.
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Normal platelet count is in the range of 150,000 to 450,000. With ITP, the platelet count is less than 100,000. By the time significant bleeding occurs, the child may have a platelet count of less than 10,000. The lower the platelet count, the greater the risk of bleeding.
Because platelets help stop bleeding, the symptoms of ITP are related to increased bleeding. However, each child may experience symptoms differently. Symptoms may include:
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- purpura - the purple color of the skin after blood has leaked under it. A bruise is blood under the skin. Children with ITP may have large bruises from no known trauma. Bruises can appear at the joints of elbows and knees just from movement.
- petechia - tiny red dots under the skin that are a result of very small bleeds.
- nosebleeds
- bleeding in the mouth and/or in and around the gums
- blood in the vomit, urine, or stool
- bleeding in the head - this is the most dangerous symptom of ITP. Any head trauma that occurs when there are not enough platelets to stop the bleeding can be life threatening.
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The symptoms of ITP may resemble other blood disorders or medical problems. Always consult your child's physician for a diagnosis.
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ITP is diagnosed by taking the patient's history, performing a complete medical exam, and evaluating blood tests. Diagnostic procedures for ITP include:
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- complete blood count (CBC) - a measurement of size, number, and maturity of different blood cells (including platelets) in a specific volume of blood.
- additional blood and urine tests (to measure clotting times and detect possible infections)
- possible bone marrow testing to identify any abnormal cells
- careful review of the child's medications
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Sometimes, a bone marrow aspiration is performed to look at the production of platelets and to rule out any abnormal cells the marrow may be producing that could lower platelet counts.
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A number of treatments can help increase platelet levels in people with ITP, but there is no cure for the disorder. The majority of children get better spontaneously, with or without treatment. The ITP Program at Childrens Hospital Boston focuses on treatment, monitoring and therapy to keep people safe until platelet counts return to healthy levels. Many children with ITP spontaneously recover in about days to weeks.
When treatment is necessary, the most common forms of treatment are:
Steroids increase the platelet count by decreasing the rate of platelet destruction and by temporarily reducing anti-platelet antibody production. Steroids may be taken by mouth. Side effects may include irritability, stomach irritation, weight gain, hypertension, sugar in the urine and acne.
Intravenous gamma globulin (IVIG) is a human blood product that contains many antibodies. IVIG comes from human plasma, the liquid part of the blood that does not contain blood cells. Special processes are used in manufacturing IVIG to make it safe. How IVIG works is not completely understood, but it slows the destruction of platelets by the spleen. IVIG is given intravenously over 3-6 hours. Temporary side effects include fever, chills, headache, muscle and joint pain, hives, rash or allergic reactions.
Rh immune globulin comes from human plasma, the liquid part of blood that contains antibodies. Special processes are used in manufacturing Rh immune globulin to make it safe. This medication temporarily stops the spleen from destroying platelets. Your child must be blood type Rh positive and have a spleen for this medication to be effective. The medication is given intravenously. Temporary side effects include mild anemia, fever, chills, headache, blood pressure changes or allergic reactions.
Other treatments for ITP may include:
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- medication changes - If it is a medication that is the suspected cause, discontinuation or changing the medication may be necessary.
- infection treatment - If infection is the cause for ITP, then treatment of the infection may result in higher platelet counts.
- splenectomy - In some cases, the child's spleen may need to be removed since this is the site of platelet destruction. This is considered more often in older children with chronic ITP to decrease the rate of platelet destruction.
- hormone therapy - Teenage girls may need to take hormones to stop their menstrual cycle if excessive bleeding occurs due to low platelet counts.
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The parents of a child with ITP need to be aware of how to prevent injuries and bleeding. Consider the following:
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- For the young child, make the environment as safe as possible. Padding a crib, wearing helmets, and providing protective clothing are necessary when platelet counts are low.
- Certain sports (contact sports) and rough play may need to be restricted.
- Avoid medications that may interfere with platelet function and may cause bleeding. These include aspirin and non-steroidal, anti-inflammatory medications (aspirin, ibuprofen, Motrin, Advil, naproxen, naprosyn, Aleve).
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It is important to discuss with your child's physician other precautions necessary to prevent injuries in a child with ITP.
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Although there is no known cause of ITP and there is no cure, the prognosis for a child with ITP is very good.
Usually, the body stops making the antibodies that attack the platelets and the disorder resolves on its own. The goal of treatment is to keep the child safe and prevent bleeding until the body corrects the problem.
Overall, prevention of serious bleeding, such as head injuries, is the most significant factor in prognosis. Providing a safe environment, prompt medical attention, and continued medical care are all indications for a long term, healthy prognosis.
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