Immune thrombocytopenia (THROM-bo-si-to-PE-ne-ah) or ITP is a rare autoimmune condition that can be as challenging to pronounce as it is to live with. Characterized by low blood platelet counts, you may hear ITP called by its original name of idiopathic thrombocytopenic purpura. Historically, “idiopathic” was used because the cause of the condition was unknown. Today we know ITP is caused by the body’s immune system destroying healthy platelets that leads to easy or excessive bruising and bleeding, in addition to initiating a daily roller coaster of emotions and ongoing medical management.

The Phases of ITP

Newly diagnosed ITP: within 3 months from diagnosis
Persistent ITP: 3 to 12 months from diagnosis.
Chronic ITP: lasting for more than 12 months

What causes ITP?

The specific cause behind why ITP develops is usually unknown and can differ from person to person. ITP has been shown to develop:

  • After a viral or bacterial infection
  • After certain immunizations
  • After exposure to a toxin
  • In association with another illness, such as lupus or HIV (human immunodeficiency virus)

While ITP can often seem mysterious as to why it occurs, the good news is that researchers continue to make progress in understanding the condition and its similarities to other autoimmune diseases. Learn more about the science behind the causes of ITP.

What are the symptoms of ITP?

The symptoms of ITP can vary greatly from person to person, and some with ITP may show no signs of having the condition. In general, the lower your platelet count, the more symptoms you may have including:

  • Easy or excessive bruising (purpura)
  • Petechiae (pe-TEEK-ee-ay), tiny red dots on the skin caused by broken blood vessels or leaks in a capillary wall
  • Bleeding from the gums or nose
  • Blood in urine or stools
  • Unusually heavy menstrual flow
  • Feeling tired or fatigued

How is ITP diagnosed?

ITP is a diagnosis of exclusion. Because there is no definitive test to diagnose ITP, your doctor will rule out other causes of low platelets, such as an underlying illness or medications you or your child may be taking. If no other cause is found, the diagnosis is often ITP.

In addition to asking about your or your child’s medical history, your doctor will perform a physical exam and run one or more of the following tests:

  • Complete blood count (CBC): A common blood test used to determine the number of blood cells, including platelets, in a sample of blood.
  • Blood smear: This test is used to confirm the number of platelets observed in a complete blood count.
  • Bone marrow exam: If blood tests show your platelet count is low, a bone marrow test may be recommended to show whether your bone marrow is making enough platelets; the American Society of Hematology doesn’t recommend this test for children with ITP[1].

Learn more about the tests used to diagnose ITP and important information to share with your doctor for the correct diagnosis.


What is the purpose of platelets?

Platelets are relatively small, disc-shaped cells circulating within your blood that bind together when recognizing damaged blood vessels. For example, when you get a cut, platelets bind to the site to cause a blood clot—and stop the bleeding. A normal platelet count is between 150,000 and 450,000 per microliter of blood. If someone has a platelet count lower than 100,000 per microliter of blood with no other reason for low platelets, they are considered to have ITP. And, because they have fewer platelets, people with ITP are more prone to prolonged bleeding. Learn more about the role and function of platelets in ITP here.

The Platelet Destruction Process

Ask the Experts Q&A

More videos with answers to common questions about ITP, symptoms, treatments, and daily life with ITP.

How often should I have my platelets checked?

Is there a big difference between a platelet count of 5K, 7K, or 10K?

What does it mean when I have large platelets, or my platelets “clump”?

How can I manage fatigue?

My low platelet count causes me anxiety. Is this normal?

Will drinking a glass of wine affect my platelet levels?

Is CBD oil effective as a treatment for ITP?

Is it safe to fly with a low platelet count?

Can I have surgery or dental work?

Can I get a tattoo when I have ITP?

[1] Neunert, C, Lim, W, et al. The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia. Blood. 2011;117:4190-4207

[2] Rodeghiero F, Stasi R, Gernsheimer T, 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(11):2386-2393.