Immune thrombocytopenia (THROM-bo-si-toe-PE-ne-ah), or ITP, is a bleeding disorder. In ITP, the blood doesn't clot as it should. This is due to a low number of blood cell fragments called platelets (PLATE-lets) or thrombocytes (THROM-bo-sites).
                
Platelets are made in your bone marrow along with other kinds of blood cells. They stick together (clot) to seal small cuts or breaks on blood vessel walls and stop bleeding.
                
Overview
                
Without enough platelets, bleeding can occur inside the body (internal bleeding) or underneath or from the skin (external bleeding).
                
People who have ITP often have purple bruises called purpura (PURR-purr-ah). These bruises appear on the skin or mucous membranes (for example, in the mouth). Bleeding from small blood vessels under the skin causes purpura.
                
People who have ITP also may have bleeding that causes tiny red or purple dots on the skin. These pinpoint-sized dots are called petechiae (peh-TEE-kee-ay). Petechiae may look like a rash.
                
Petechiae and Purpura
                

                
People who have ITP also may have nosebleeds, bleeding from the gums during dental work, or other bleeding that's hard to stop. Women who have ITP may have menstrual bleeding that's heavier than normal.
                
A lot of bleeding can cause hematomas (he-mah-TO-mas). A hematoma is a collection of clotted or partially clotted blood under the skin. It looks or feels like a lump.
                
Bleeding in the brain as a result of ITP is very rare, but can be life threatening if it occurs.
                
In most cases, an autoimmune response is thought to cause ITP. Normally, your immune system helps your body fight off infections and diseases. But if you have ITP, your immune system attacks and destroys its own platelets. The reason why this happens isn't known.
                
ITP can't be passed from one person to another.
                
Types of Immune Thrombocytopenia
                
The two types of ITP are acute (temporary or short-term) and chronic (long-lasting).
                
Acute ITP generally lasts less than 6 months. It mainly occurs in childrenboth boys and girlsand is the most common type of ITP. Acute ITP often occurs after a viral infection.
                
Chronic ITP lasts 6 months or longer and mostly affects adults. However, some teenagers and children do get this type of ITP. Chronic ITP affects women two to three times more often than men.
                
Treatment depends on the severity of bleeding and the platelet count. In mild cases, treatment may not be needed.
                
Outlook
                
For most children and adults, ITP isn't a serious or life-threatening condition.
                
Acute ITP in children often goes away on its own within a few weeks or months and doesn't return. In 80 percent of children who have ITP, the platelet count returns to normal within 6 to 12 months. Treatment may not be needed.
                
For a small number of children, ITP doesn't go away on its own and may require further medical or surgical treatment.
                
Chronic ITP varies from person to person and can last for many years. Even people who have severe forms of chronic ITP can live for decades. Most people who have chronic ITP can stop treatment at some point and maintain a safe platelet count.