Immune Thrombocytopenic Purpura (ITP)
The information provided is not intended to be a substitute for professional medical advice. A licensed healthcare professional should be consulted for diagnosis and treatment of any and all medical conditions.
What is ITP?
Immune Thrombocytopenic Purpura (ITP) is an autoimmune disease characterized by a low blood platelet count, sometimes referred to as Idiopathic Thrombocytopenic Purpura, occurs when your body’s immune system destroys its own platelets, in the same way it would destroy harmful invaders such as bacteria. Platelets are important for helping the blood to clot and stop bleeding.
Usually when foreign invaders (pathogens) are detected by the immune system, the body makes antibodies which then coat the bacteria, marking them for destruction. In ITP, the body mistakenly produces antibodies against its own platelets. The immune system has lost some of its ability to distinguish between foreign substances and the body’s own cells. The antibody-coated platelets are destroyed by specialized cells called macrophages, which exist in large numbers in the spleen.
In some patients, the low platelet counts seen in ITP may be due to impaired platelet production that may occur along with antibody-mediated destruction of platelets1,2
Incidence of ITP
- Estimated incidence of ITP is 100 cases per million per year.2
- The Platelet Disorder Support Association (PDSA) estimates that there are approximately 200,000 people in the United States with ITP. 3
- Recent studies show similar incidence of ITP in newly diagnosed men and women, with highest incidence in those over 60 years of age.4
Types of ITP
ITP can be classified as primary or secondary to another disease (e.g. AIDS, Lupus).
ITP can also be classified as acute (<6 - month duration) or chronic (>6 - month duration). Children are much more likely to have the acute form of ITP. In adults, ITP is often chronic.
The main symptoms of ITP are bruising and bleeding, which can include:5
- Spontaneous bruising (purpura): purplish areas on skin or mucous membranes
- Petechiae: pinpoint red spots on the skin (typically the legs) that often occur in groups and may look like a rash
- Bleeding that is hard to stop
- Bleeding from gums
- Heavy menstrual bleeding in women (menorrhagia)
- Blood in the urine
- Blood in the stool
Bleeding into the brain, a complication of ITP, is rare, but can be life threatening if it occurs. The risk of intracranial bleeding is greatest in:
- the elderly
- patients with a history of bleeding
- patients who don't respond to therapy
- patients with platelet counts that fall below 10,000/mm3 to 20,000/mm3. 6
Your doctor may decide whether or not treatment is necessary, depending upon your symptoms, platelet counts, and other laboratory test results. Patients with chronic ITP may receive different therapies over the course of treatment. No single therapy is right for every patient in all situations.
Initial treatment of children with acute ITP remains a topic of debate among physicians because often the disease resolves without any treatment. Treatment may be necessary to prevent restrictions of physical activity and prevention of excessive bleeding.2
Approximately half of adults presenting to their physicians with symptoms of ITP have platelet counts below 10,000/mm3, putting them at risk for excessive bleeding. Therefore, adults generally require treatment at the time of diagnosis.2
1. Ballem P.J., Segal G.M., Stratton J.R., Gernsheimer T, Adamson JW, Slichter SJ. Mechanisms of thrombocytopenia in chronic autoimmune thrombocytopenic purpura. Evidence of both impaired platelet production and increased platelet clearance. J Clin Invest. 1987;80:33-40.
2. Cines D.B., Blanchette V.S. Immune Thrombocytopenic Purpura. New England Journal of Medicine. 2002; 346(13): 995-1008.
3. Platelet Disorder Support Association website 2007. About ITP. Available at: http://www.pdsa.org/itp-information/index.html. Accessed September 7, 2007.
4. Neylon et al. Clinically significant newly presenting autoimmune thrombocytopenic purpura in adults: a prospective study of a population-based cohort of 245 patients. Br J Haematol. 2003; 122:966-974.
5. National Institutes of Health. National Heart, Lung and Blood Institute Diseases and Conditions Index. What Are the Signs and Symptoms of Idiopathic Thrombocytopenic Purpura? Available at http://www.nhlbi.nih.gov/health/dci/Diseases/Itp/ITP_ SignsAndSymptoms.html. Accessed September 14, 2007.
6. Cines, D., Bussel, J. How to Treat ITP, Blood. 2005; 7(106): 2244-2251.