Thrombocytopenia (throm-boe-sie-toe-PEE-nee-uh) is a condition in which blood doesn't clot properly because there aren't enough platelets. Platelets (thrombocytes) are small pieces of cells that play an important role in blood clotting by clumping and forming plugs when necessary.

Causes of thrombocytopenia include increased breakdown and destruction of platelets (related to a problem with the immune system), reduced production of platelets or trapping of platelets in the spleen. Thrombocytopenia can be caused by another condition or disorder, such as leukemia, lymphoma, bone marrow failure (aplastic anemia), some viruses or bacterial infections, certain genetic conditions, as a medication side effect, or from exposure to certain toxic chemicals.

The most common reason for thrombocytopenia in children is idiopathic thrombocytopenic purpura (ITP), also called immune system thrombocytopenia. Idiopathic means unknown cause. ITP occurs when the immune system mistakenly attacks and destroys platelets. If ITP in children lasts longer than six months, it's known as chronic ITP.

Treatment depends on the cause of your child's thrombocytopenia, and in some cases, treatment might not be necessary. Thrombocytopenia may improve if an underlying cause is identified and treated. Treatment for thrombocytopenia may include medications, such as corticosteroids or immune-suppressing drugs, and blood or platelet transfusions.