Immune (Idiopathic) Thrombocytopenia Purpura
What is immune thrombocytopenic purpura (ITP)?
ITP is a blood disorder characterized by an abnormal decrease in the number of platelets in the blood. Platelets are cells in the blood that help stop bleeding. A decrease in platelets can result in easy bruising, bleeding gums, and internal bleeding. The older name that is still sometimes seen is idiopathic thrombocytopenic purpura.
Idiopathic means the cause is unknown.
Thrombocytopenia means a decreased number of platelets in the blood.
Purpura refers to the purple discoloring of the skin, as with a bruise.
The new name that is coming into use is immune thrombocytopenic purpura. The word immune more accurately describes that ITP is an immunologic disease where the body destroys its own platelets.
Who is affected by ITP?
ITP affects approximately four to eight per 100,000 children under the age of 15 each year in the US. There are two forms of ITP:
Acute thrombocytopenic purpura
This is most commonly seen in young 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). Treatment is often not needed. The disorder usually does not recur. Acute ITP is the most common form of the disorder.
Chronic thrombocytopenic purpura
The onset of the disorder can happen at any age, and the symptoms can last a minimum of six months, several years, or a lifetime. Adults have this form more often than children, but it does affect adolescents. Females have it two to three times more often than males. Chronic ITP can recur often and requires continual follow-up care with a blood specialist (hematologist).
What causes ITP?
In most cases, the cause of ITP in children is unknown. It is not contagious, meaning a child cannot "catch it" from playing with another child with ITP. It is also important to know that nothing the parents, nor the child, did caused the disorder.
Often, the child may have had a virus or viral infection about three weeks before developing ITP. It is believed that the body, when making antibodies against a virus, "accidentally" also made an antibody that can stick to the platelet cells. The body recognizes any cells with antibodies as foreign cells and destroys them. That is why ITP is referred to as immune thrombocytopenic purpura.
The bone marrow is the soft, spongy center of the long bones and is 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. A physician can look at the cells in the bone marrow and, in a child with ITP, would see many young platelets that have been produced. However, the blood test results of the circulating blood would show a very low number of platelets. The body is producing the cells normally, but the body is also destroying them. In most cases, other blood tests are normal except for the low number of platelets. ITP platelets usually survive only a few hours, in comparison to normal platelets which have a lifespan of 7 to 10 days.
Platelets are essential for the formation of a blood clot. Blood clots consist of a mass of fibers and blood cells. Platelets travel to a damaged area and stick together to form a plug, whenever a person is cut, for example. If there are not enough platelets, a clot cannot be formed, resulting in more bleeding.
There has been research involved in looking at certain medications causing ITP. Some medications may result in the altering of platelet function. At this time, no proven direct link has been made with any specific medication that may cause ITP.
What are the symptoms of ITP?
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:
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.
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.
The symptoms of ITP may resemble other medical problems. Always consult your child's doctor for a diagnosis.
How is ITP diagnosed?
In addition to a complete medical history and physical examination, diagnostic procedures for ITP may include:
Complete blood count (CBC)--a measurement of size, number, and maturity of different blood cells in a specific volume of blood (to measure platelets).
Additional blood and urine tests (to measure bleeding time and detect possible infections), including a special blood test called an "anti-platelet antibody test"
Careful review of the child's medications
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, but it is not always necessary, especially for children and in mild cases.
Treatment for ITP
Specific treatment for ITP will be determined by your child's doctor based on:
Your child's age, overall health, and medical history
Type of disorder (acute versus chronic)
Severity and extent of the disorder
Your child's tolerance for specific medications, procedures, or therapies
Expectations for the course of the disease
Your opinion or preference
Not all children with ITP require treatment. Close monitoring of your child's platelets and prevention of serious bleeding complications may be the course of action chosen until the body is able to correct the disorder on its own. Many children with ITP are able to spontaneously recover within 6 months.
When treatment is necessary, the two most common forms of treatment are steroids and intravenous gamma globulin:
Steroids help prevent bleeding by decreasing the rate of platelet destruction. Steroids, if effective, will result in an increase in platelet counts seen within two to three weeks. Side effects may include irritability, stomach irritation, weight gain, hypertension, and acne.
Intravenous gamma globulin (IVGG)
Intravenous gamma globulin (IVGG) is a protein that contains many antibodies and also slows the destruction of platelets. IVGG works more quickly than steroids (within 24 to 48 hours).
Other treatments for ITP may include:
Rh immune globulin
This medication temporarily stops the spleen from destroying platelets. Your child must be Rh positive and have a spleen for this medication to be effective.
If it is a medication that is the suspected cause, discontinuation or changing the medication may be necessary.
If infection is the cause for ITP, then treatment of the infection may result in higher platelet counts.
In some cases, the child's spleen may need to be removed since this is the most active site of platelet destruction. This is considered more often in older children and adults with chronic ITP to decrease the rate of platelet destruction.
Teenage girls may need to take hormones to stop their menstrual cycle when their platelets are low if excessive bleeding occurs.
The FDA approved two new medications for ITP: N-plate and Promacta. They stimulate the bone marrow to produce more platelets.
The parents of a child with the disorder need to be aware of how to prevent injuries and bleeding. Consider the following:
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.
Contact sports, riding bicycles, and rough play may need to be restricted.
Avoid medications which contain aspirin, as they may interfere with the body's ability to control bleeding.
It is important to discuss with your child's doctor other limitations necessary to prevent injuries in a child with ITP.
Long-term outlook for ITP
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 are attacking the platelets and the disorder resolves on its own. The goal of treatment is to keep the child's platelets in a safe range 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 necessary for a long-term, healthy prognosis.