Q: What is ITP?
A: ITP, immune thrombocytopenia, is an autoimmune disease. In autoimmune diseases, the body mounts an immune attack toward one or more seemingly normal organ systems. In ITP, platelets are the target. They are marked as foreign by the immune system and eliminated in the spleen and sometimes, the liver. In addition to increased platelet destruction, some people with ITP also have impaired platelet production.
Q: What are platelets?
A: Platelets are relatively small, disc-shaped cells in our blood. They are required to maintain the integrity of our blood vessel walls and for blood to clot. Without a sufficient number of platelets, a person with ITP is subject to spontaneous bleeding or bruising. It is possible, with a very low platelet count, to have spontaneous bleeding including a cerebral hemorrhage.
Q: What is a normal platelet count?
A: According to Mosby’s Manual of Diagnostic and Laboratory Tests (4th Ed., 2010) normal platelet counts range from 150,000 to 400,000 per microliter of blood. The Merck Manual for Health Care Professionals (2011 Ed.) cites a normal platelet count range from 140,000 to 440,000. Reference ranges differ slightly depending upon the specific lab performing the test. Patients with platelets less than 140,000 are considered to have thrombocytopenia (low platelets). A platelet count less than 100,000 might be considered ITP according to the International Consensus Report on the Investigation and Management of Primary Immune Thrombocytopenia (Blood, Jan. 14, 2010). People with platelet counts under 10,000 have a severe case of ITP. For many, a count of 30,000 or more is sufficient to prevent a serious bleed.
Q: What causes ITP?
A: The specific cause of ITP is unknown. Some cases appear after a viral or bacterial infection, after immunizations, after exposure to a toxin, or in association with another illness such as lupus or HIV.
Q: Can you inherit ITP?
A: ITP is not usually considered a disease that can be passed from one generation to another. There are cases in which multiple family members have been diagnosed with ITP, but most researchers consider these a misdiagnosis.
Q: What are the symptoms of ITP?
A: The symptoms vary greatly from person to person. Most people with ITP experience spontaneous bruising. Some find they have petechiae (pe-TEEK-ee-ay), tiny red dots on the skin caused by broken blood vessels or leaks in a capillary wall. If the platelet count is very low other bleeding symptoms include blood blisters on the inside of the cheeks or blood in the urine or stool. In general, the more bleeding symptoms, the lower the platelet count.
Q: How is ITP diagnosed?
A: ITP is a diagnosis of elimination. A doctor will do tests that rule out other causes of low platelets. If no other cause is found, then the diagnosis is often ITP. There is no accurate, definitive test for ITP.
Q: Can ITP be cured?
A: While there is no cure for ITP, many patients find their platelet count improves following treatment. What proves difficult for many ITP patients is finding the treatment that works for them without unwanted side effects. Some patients report that changing their diet or lifestyle helps them feel better. The disease can go into remission for a long time, perhaps for the remainder of a person’s life. ITP can also recur. There is currently no way to predict the course of the disease.
Q: How is ITP different in children than in adults?
A: ITP can be either acute (sudden onset, often temporary) or chronic (long lasting). Most children (80-90%) have acute ITP. These children usually recover within a few months whether they receive treatment or not. Recovery is possible even if your child is considered to have chronic ITP.
Q: How do children get ITP?
A: Doctors don’t know what causes ITP, but it often occurs in otherwise healthy children a few days or weeks after a viral infection. It’s thought that for some unknown reason this infection causes the immune system to lose the ability to distinguish between the body’s own cells and those of invaders. There is also some evidence that certain vaccines may trigger ITP, but this occurs in only a small percentage of cases. Why ITP happens in some children and not others who have had the same infection, virus or vaccine is not known.