This section has been reviewed and approved by the PLWC Editorial Board, 02/05

Thrombocytopenia is an unusually low level of platelets in the blood. Platelets, also called thrombocytes, are the blood cells that stop bleeding by plugging damaged blood vessels and helping the blood to clot. People with low levels of platelets bleed more easily and are prone to bruising.


Platelets and red and white blood cells are made in the bone marrow, a spongy, fatty tissue found on the inside of larger bones. Certain types of chemotherapy drugs can damage the bone marrow so that it does not make enough platelets. Thrombocytopenia caused by chemotherapy is usually temporary. Nonchemotherapy medications may also lower the number of platelets. In addition, a personís body can make antibodies to the platelets, which lowers the number of platelets. Radiation therapy alone does not usually cause thrombocytopenia, unless there is a significant amount of radiation of the pelvis, the patients are also receiving chemotherapy, or there is metastasis (spread) to the bone.

Thrombocytopenia can also occur when cancer cells, such as leukemia or lymphoma cells, crowd normal bone marrow cells. Although rare, thrombocytopenia can also occur when other cancers, such as prostate or breast cancer, spread to the bone marrow. While also less common, cancer of the spleen can cause thrombocytopenia. Excess platelets are stored in the spleen, and cancer of the spleen can cause the spleen to enlarge and trap too many platelets.

Signs and symptoms

People with thrombocytopenia may experience some of these symptoms:

  • Unexpected bruising
  • Small purple or red spots under the skin, called petechia
  • Bleeding from the nose or gums
  • Heavier than usual menstrual periods
  • Black or bloody bowel movements or reddish or pinkish urine
  • Blood in the vomit
  • Bad headaches
  • Dizziness
  • Pain in the joints or muscles
  • Increased weakness

Often, symptoms do not occur until the level of platelets is very low and many patients do not know they have thrombocytopenia until it is diagnosed during a routine blood test.Report any symptoms of thrombocytopenia to your doctor immediately.

Diagnosis and treatment

Thrombocytopenia is diagnosed with a blood test that counts the actual number of platelets in a sample of blood. This test is called a platelet count. People with certain types of cancer or who are undergoing cancer treatment that is known to cause thrombocytopenia may receive regular blood tests to look for thrombocytopenia and other blood-related complications.

People whose platelet counts drop while receiving chemotherapy may receive a lower dose or wait longer between chemotherapy cycles. Due to the risk of bleeding, surgery is usually delayed until platelets counts are restored to a normal level.

Due to the risk of hemorrhage (spontaneous, heavy bleeding), people with a low platelet level may be given a transfusion of platelet cells. However, transfused platelets only last about three days, and some patients may need multiple transfusions. In addition, some patients receiving chemotherapy may be given a drug called oprelvekin (Neumega) to help prevent severe thrombocytopenia.

Patient considerations

Along with treatment from your doctor, the following tips will help you avoid problems if your platelet level is low:

  • Don't drink alcohol or take any medications without asking your doctor first, as many medications can make bleeding problems worse.
  • Use an extra soft toothbrush and don't floss if your gums bleed.
  • Blow your nose gently using a soft tissue.
  • Be careful using scissors, knives, needles, or tools, and be careful not to burn yourself when cooking.
  • Shave with an electric razor.
  • Avoid contact sports and other activities that might cause injury.

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