Definition of Thrombocytopenia:

Thrombocytopenia is any disorder in which there are not enough platelets. Platelets are cells in the blood that help blood to clot. This condition is sometimes associated with abnormal bleeding.

Causes, incidence, and risk factors:

Thrombocytopenia is often divided into three major causes of low platelets:

1. Low production of platelets in the bone marrow
2. Increased breakdown of platelets in the bloodstream (called intravascular)
3. Increased breakdown of platelets in the spleen or liver (called extravascular)

Disorders that involve low production in the bone marrow include:

• Aplastic anemia
• Cancer in the bone marrow
• Infections in the bone marrow (very rare)
• Myelodysplasia

Use of certain drugs may also lead to a low production of platelets in the bone marrow, although this is rare.

Disorders that involve the breakdown of platelets include:

• Disseminated intravascular coagulation (DIC)
• Drug-induced nonimmune thrombocytopenia
• Drug-induced immune thrombocytopenia
• Hypersplenism
• Immune thrombocytopenic purpura (ITP)
• Thrombotic thrombocytopenic purpura