Definition of Thrombocytopenia:

Thrombocytopenia is any disorder in which there is an abnormally low amount of platelets. Platelets are parts of 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
• Cirrhosis (chronic liver disease)
• Folate deficiency
• Infections in the bone marrow (very rare)
• Myelodysplasia
• Vitamin B12 deficiency

Use of certain drugs may also lead to a low production of platelets in the bone marrow. The most common example is chemotherapy treatment.

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