Immune thrombocytopenic purpura

Alternative names

Idiopathic thrombocytopenic purpura (ITP); ITP

Definition

Idiopathic thrombocytopenic purpura is a bleeding disorder characterized by too few platelets in the blood. This is because platelets are being destroyed by the immune system. Idiopathic means the exact cause of the disease is unknown.

Because more is being learned about the autoimmune nature of the disease, it is sometimes called immune thrombocytopenic purpura.

Causes, incidence, and risk factors

The disease occurs when immune system cells, called lymphocytes, produce antibodies against platelets. Platelets are necessary for normal blood clotting. They clump together to plug small holes in damaged vessels.

The presence of antibodies on platelets leads to their destruction in the spleen. A characteristic skin rash, easy bruising, abnormal menstrual bleeding, or sudden and severe loss of blood from the gastrointestinal tract may occur.

Usually, no other abnormal findings are present. In children, the disease is sometimes preceded by a viral infection and usually runs its course without treatment. In adults, it is more often a chronic (long-term) disease and can follow a viral infection, certain drugs, pregnancy, or other immune disorders.

ITP affects women more frequently than men, and is more common in children than adults. There is no sex difference in children.

Symptoms

• Bruising
  
• Nosebleed or oral bleeding
  
• Bleeding into the skin - also called pinpoint red spots and petechial rash
  
• Abnormally heavy menstruation
  

Signs and tests
Tests include:

• Complete blood count (CBC) shows low platelet count.
  
• Bone marrow aspiration or biopsy appears normal.
  
• PTT (coagulation studies) is normal.
  
• PT (coagulation studies) is normal.
  
• Platelet associated antibodies may be detected.
  

Treatment

In children, the disease often runs its course without treatment.

In adults, the initial treatment is usually with a drug called prednisone. A splenectomy (removal of the spleen) is sometimes advised. The spleen is the major site of platelet destruction, but removal of the spleen will only bring up the platelet count in 50% of people.