Immune thrombocytopenia purpura (ITP) is a bleeding disorder. It is a reduction in the number of platelets in your blood. Platelets are small cells in your blood that stick together to form blood clots. These clots help stop bleeding at injury sites. Low platelet levels with ITP makes it easier to develop bruises or bleed even with minor injuries.

There are two types of ITP:

  • Acute ITP
    • Lasts less than six months.
    • Usually occurs in children.
    • Most common type of ITP.
  • Chronic ITP
    • Lasts longer than six months.
    • Usually occurs in adults.

ITP is caused by a problem with the immune system. The immune system places a tag on platelet cells. This tag mistakenly identifies platelets as foreign material. Organs like the spleen and liver will then remove the tagged platelets as they pass through in the blood. Gradually, this process will reduce the number of platelet in your blood. Eventually, the decreased levels of platelets will be severe enough to interfere with the blood's ability to clot.

Spleen
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For most ITP, it is not clear what causes the problem with immune system. In children, ITP is often associated with a recent infection with a virus. ITP in adults has not been linked to viruses.

Some cases of ITP are thought to be caused by drugs or other immune disorders.