Thrombocytopenia is defined as an abnormal reduction in platelet count leading to an increased tendency to bruise or bleed. Platelets, also known as thrombocytes, are the tiny cells in the blood that are responsible for blood clotting.

The blood usually contains about 140,000 to 440,000 platelets per microliter. Bleeding can occur with relatively minor trauma when the platelet count falls below about 50,000 platelets per microliter of blood. The most serious risk of bleeding, however, generally does not occur until the platelet count falls below 10,000 to 20,000 platelets per microliter. At these very low levels, bleeding may occur without any injury.


Idiopathic Thrombocytopenic Purpura (ITP): ITP is a disease in which antibodies form and destroy the body's platelets. Why the antibodies form is not known. Although the bone marrow increases platelet production to compensate for the destruction, the supply cannot keep up with the demand.


Purpura (TTP): TTP is a rare disease in which small blood clots form suddenly throughout the body. The blood clots mean that an abnormally high number of platelets are being used, which leads to a sharp decrease in the number of platelets in the bloodstream.

Hemolytic-Uremic Syndrome (HUS): HUS is a disorder related to TTP in which the number of platelets suddenly decreases, red blood cells are destroyed, and the kidneys stop functioning. The syndrome is most common in infants, young children, and women who are pregnant or have just given birth, although it can occur in older children, adults, and women who are not pregnant.


Thrombocytopenia can result from conditions that affect the bone marrow and disrupt the production of platelets from bone marrow stem cells including:

  • Anemia (low red blood cell count).
  • Bone marrow cancer.
  • Bone marrow infection.
  • Chemotherapy.
  • Cirrhosis of the liver.
  • Medication side effects.
  • Myelodysplasia (low production of certain types of blood cells).
  • Vitamin B12 or folate deficiency (as in pernicious anemia).

Causes of platelet breakdown in the bloodstream, liver and spleen.

Thrombocytopenia may also result from conditions that lead to the excessive breakdown of blood cells in the bloodstream, liver and spleen including:

  • Disseminated intravascular coagulation (DIC).
  • Hemolytic uremic syndrome (rare disease characterized by kidney failure and multiple blood clots).
  • Hypersplenism (overactive spleen).
  • Immune- and nonimmune-induced breakdown of blood cells.
  • Immune thrombocytopenic purpura and thrombotic thrombocytopenic purpura (rare conditions in which small blood clots form throughout the body, resulting in low platelet levels).
  • Medication side effects.

A number of factors increase the risk of developing thrombocytopenia. Not all people with risk factors will get thrombocytopenia. Risk factors for thrombocytopenia include:

  • Anemia (low red blood cell count).
  • Certain types of cancer such as leukemia (cancer of the blood or bone marrow).
  • Certain viral or bacterial infections.
  • Chemical or environmental toxin exposure.
  • Family history of low platelet counts.


Bleeding in the skin may be the first sign of a low platelet count. Many tiny red dots (petechiae) often appear in the skin on the lower legs, and minor injuries may cause small scattered bruises. The gums may bleed, and blood may appear in the stool or urine. Menstrual periods may be unusually heavy. Bleeding may be hard to stop.

Bleeding worsens as the number of platelets decreases. People who have very few platelets may lose large amounts of blood into the digestive tract or may develop life-threatening bleeding in the brain even though they have not been injured.

The rate at which symptoms develop can vary depending on the cause of thrombocytopenia. For example, in TTP and HUS, symptoms develop suddenly. In ITP, symptoms may develop suddenly or gradually and subtly.

Symptoms in TTP and HUS are quite distinct from symptoms of most other forms of thrombocytopenia. In TTP, the small blood clots that develop (using up platelets) cause a wide range of symptoms and complications, some of which can be life threatening.


Symptoms that result from clots in the brain may include headache, confusion, seizures, and coma. Symptoms that result from clots elsewhere in the body include abnormal heart rhythms, blood in the urine that accompanies kidney damage, and abdominal pain. The predominant symptoms and complications of HUS are related to blood clots that develop in the kidneys, causing damage that is usually severe and may progress to kidney failure.


In mild cases of thrombocytopenia, no treatment may be required. For moderate cases, treatment depends on the cause of thrombocytopenia. In cases related to medications or environmental contaminants, thrombocytopenia may resolve on its own once the underlying cause is removed. In other moderate cases, medication may be prescribed in order to increase platelet counts.


Corticosteroids, to prevent platelet breakdown. Immunoglobulins to boost platelet production. In severe thrombocytopenia, procedures such as blood transfusion, platelet transfusion, or splenectomy (surgical removal of the spleen) may be necessary.

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