What is Immune Thrombocytopenia?

A Review of Symptoms, Diagnosis, and Treatment

Platelets in circulation
Platelets in circulation. Science Photo Library - SCIEPRO/Brand X Pictures/Getty Images

Definition 

Immune thrombocytopenia (ITP), previously called idiopathic thrombocytopenic purpura, is a condition where your body’s immune system attacks and destroys your platelets causing low platelet counts (thrombocytopenia). Platelets are needed to clot blood and if you do not have enough, you may experience bleeding.   

Symptoms of ITP

Symptoms of ITP are related to the increased risk of bleeding due to your low platelet count.

However, many people with ITP are without symptoms.    

  • Nosebleeds 

  • Bleeding from the gums

  • Blood in urine or stool 

  • Excessive menstrual bleeding known as menorrhagia

  • Petechiae - these small red dots might resemble a rash but are actually a small amount of bleeding under the skin

  • Easy bruising - the bruises may be large and able to be felt beneath the skin

  • Blood blisters in the inside of the mouth known as purpura   

Causes of ITP 

In general, your platelet count drops in ITP because your body makes antibodies that attach to the platelets and marks them for destruction. When these platelets flow through the spleen (organ in the belly that filters blood), it recognizes these antibodies and destroys the platelets. Also the production of platelets might be reduced. ITP typically develops after some inciting event, sometimes your physician may be unable to determine what this event was. 

  • Viruses:  In children, ITP is often triggered by a viral infection. The viral infection usually occurs a couple of weeks prior to the development of ITP. While the immune system makes antibodies to fight the viral infection it accidentally also makes antibodies that attach to the platelets. 

  • Immunizations:  ITP has been associated with the administration of the MMR (measles, mumps, rubella) vaccine. It generally occurs within 6 weeks of receiving the vaccine. It is important to recognize that this is a rare event with 2.6 cases for every 100,000 MMR vaccinations given. This risk is smaller than the risk of developing ITP if you had measles or rubella infection. Severe bleeding is rare in these cases and more than 90% of people will have resolution of ITP within 6 months. 

  • Autoimmune disease:  ITP is considered an autoimmune disorder and is associated with other autoimmune diseases like lupus and rheumatoid arthritis. ITP may the initial presentation of one of these medical conditions.

Diagnosis of ITP

Similar to other blood disorders like anemia and neutropenia, ITP is identified on a complete blood count (CBC). There is no one diagnostic test for ITP. It is a diagnosis of exclusion, meaning other causes have been ruled out. In general, only the platelet count is decreased in ITP; the white blood cell count and hemoglobin are normal. Your health care provider may have the platelets examined under a microscope (called a peripheral blood smear) to ensure that the platelets are decreased in number but appear normal. In the midst of the workup, you may have other testing to rule out cancer or other reasons for a low platelet count, but this is not always required. If your ITP is thought to be secondary to an autoimmune disease, you may have to test specifically for this.

 

Treatment of ITP 

Currently, the treatment of ITP is dependent on the presence of bleeding symptoms rather than a specific platelet count. The goal of therapy is to stop bleeding or to bring the platelet count up to a "safe" range. Although technically not a "treatment", people with ITP should avoid taking aspirin or ibuprofen-containing medications as these medications decrease the function of platelets.  

  • Observation:  If you are not having any bleeding symptoms currently, your physician may choose to watch you closely without giving medications. 

  • Steroids:  Steroids like methylprednisolone or prednisone are the most common medication used to treat ITP worldwide. Steroids reduce the destruction of platelets in the spleen. Steroids are very effective but it may take more than a week to increase your platelet count.  

  • IVIG: Intravenous immune globulin (IVIG) is a common treatment for lTP. It is generally used for patients with bleeding who need a rapid rise in the platelet count. It is administered as an intravenous (IV) infusion over several hours.  

  • WinRho: WinRho is a IV medications that can be used to increase the platelet count in people with certain blood types. It is a faster infusion than IVIG.  

  • Platelet transfusion: Platelet transfusions are not always helpful in people with ITP but may be used in certain circumstances like if you need to undergo an operation. 

If your ITP persists and does not respond to initial treatments you doctor may recommend other treatments such as:  

  • Splenectomy:  In ITP the platelets are destroyed in the spleen. By removing the spleen, the  life expectancy of the platelets can be increased. Benefits and risks should be weighed prior to deciding to remove the spleen.   

  • Rituximab:  Rituximab is a medication called a monoclonal antibody. This medication helps to destroy the white blood cells that produce the antibodies against platelets, called B-cells. The hope is that when your body produces new B-cells, they will no longer make the antibody against the platelet. 

  • Thrombopoietin agonists: Some of the newest treatments are thrombopoietin (TPO) agonists. These medications are eltrombopag (oral) or romiplostim (subcutaneous); they stimulate your bone marrow to make more platelets. 

The differences in children and adults 

It is important to note that the natural history of ITP is often different in children versus adults. More than 80% of children diagnosed with ITP will have complete resolution. Adolescents and adults are more likely to develop chronic ITP which becomes a lifelong medical condition that may or may not require treatment. 

Source: 

CE Neunert, DL Yee. Disorders of Platelets. In: CD Rudolph, AM Rudolph, GE Lister, LR First and AA Gershon eds. Rudolph's Pediatrics. 22nd ed. New York:McGraw Hill Medical, 2011.

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