What is immune thrombocytopenia (ITP)?
Immune thrombocytopenia (ITP), also known as autoimmune thrombocytopenia, is a type of thrombocytopenia — a condition in which there are too few blood-clotting cells called platelets. Without enough platelets in your blood, you might bruise or bleed easily and dangerous internal bleeding can develop.
A number of diseases and conditions can cause too few platelets, but in ITP it's the body's germ-fighting immune system that's to blame. Something happens to make your immune system attack your platelets.
What does the name mean?
The term "immune" in ITP indicates that the condition is caused by the immune system, which usually fights off germs, including bacteria and viruses. The term "thrombocytopenia" in ITP means too few platelets (also called thrombocytes).
ITP used to be known as idiopathic thrombocytopenia purpura. Idiopathic is a term that means the cause is unknown. Purpura is a common symptom of ITP that looks like blotchy reddish or purplish spots on the skin.
What causes ITP?
ITP is caused by something that disrupts the immune system and makes it attack the blood-clotting cells called platelets that are found in the blood circulating through your body. Researchers also think the immune system interferes with the cells that make platelets (called megakaryocytes) that are in the spongy material inside your bones (bone marrow).
For most people with ITP, it's not known what causes the immune system to attack the platelets. If there's no known cause for your ITP, it's considered primary ITP.
Sometimes ITP happens in response to another condition, such as an infection. Infections that can cause ITP include HIV, hepatitis C and H. pylori. ITP can also happen in people who have other immune system problems, such as lupus. When ITP happens in response to another condition, it's called secondary ITP. Treating the associated condition usually helps treat the ITP, too.
Who gets ITP?
ITP is a common condition. It can affect anyone, but it happens most often in young children and older adults. It occurs more often in women, but anyone can develop ITP.
In young children, ITP tends to happen after an infection. Most children with ITP don't need treatment and the condition goes away on its own in a few months.
In adults, the cause of ITP usually isn't known. Most people find out they have ITP during a routine blood test. There might not be any symptoms at first. In adults, ITP doesn't go away on its own, and it usually needs treatment.
Is ITP life-threatening?
For most people with ITP, the condition isn't life-threatening. In children, the condition usually goes away on its own. In adults, treatment might not be needed right away. But if the number of platelets drops very low, treatment can increase the number of platelets in the blood and reduce the risk of serious bleeding problems.
Still, ITP can be dangerous if the number of platelets in the blood drops very low. An extremely low platelet count could cause internal bleeding. For this reason, your doctor may recommend careful monitoring of your platelet count.
May 22, 2020
See more In-depth
- AskMayoExpert. Immune thrombocytopenia (adult). Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2019.
- Hoffman R, et al. Diseases of platelet number: Immune thrombocytopenia, neonatal alloimmune thrombocytopenia and posttransfusion purpura. In: Hematology: Basic Principles and Practice. 7th ed. Philadelphia, Pa.: Elsevier; 2018. https://www.clinicalkey.com. Accessed April 25, 2019.
- Rodeghiero F, et al. Standardization of terminology, definitions and outcome criteria in immune thrombocytopenic purpura of adults and children: Report from an international working group. Blood. 2009;113:2386.
- Immune thrombocytopenia. National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health-topics/immune-thrombocytopenia. Accessed April 25, 2019.