Low Platelet Count or Thrombocytopenia

Approved by the Cancer.Net Editorial Board, 08/2020

When you have cancer or when you receive treatment for cancer, your levels of certain blood cells can go below normal. Platelets are one of these types of blood cells. The medical terms for a low level of platelets are "low platelet count" or "thrombocytopenia."

Platelets help stop bleeding when needed. For example, if you cut yourself, platelets make the blood cells clump together, or clot. This blocks off the cut blood vessels so they can heal. Normal platelet levels in your blood are important for your health.

You can develop a low platelet count if your body does not make enough platelets or if your body loses or destroys platelets. A low platelet count is a common side effect of cancer and treatment. For example, chemotherapy can lower your platelet count.

What are the signs of a low platelet count?

If your platelet count is low, you may not have any symptoms or signs. A simple blood test could find this condition before you notice any changes. If you have any of these signs, talk to your health care team right away:

  • More bruises, or worse bruises, than usual

  • Small purple or red dots under your skin

  • Nosebleeds or bleeding gums

  • Black or bloody-looking bowel movements

  • Red or pink urine

  • Vomit with blood in it

  • An unusually heavy menstrual period

  • Severe headaches

  • Muscle or joint pain

  • Feeling weak or dizzy

When you have a low platelet count, your body may have difficulty stopping bleeding from a nosebleed or a cut.

Managing a low platelet count and other cancer side effects is an important part of your medical care and treatment. This type of care is called palliative care or supportive care.

What can cause a low platelet count?

There are several common causes, including:

Chemotherapy. Some types of cancer medications, such as chemotherapy, damage bone marrow. This is the tissue inside your bones where your body makes platelets. A low platelet count from chemotherapy is usually temporary. It is rare that chemotherapy permanently damages bone marrow cells.

Radiation therapy. Radiation therapy does not usually cause a low platelet count. But your platelet levels may go down if you receive a large amount of radiation therapy to your pelvis or if you have radiation therapy and chemotherapy at the same time.

Antibodies. Your body makes proteins called antibodies. They destroy substances that may harm you, such as bacteria and viruses. But sometimes the body makes antibodies that destroy healthy platelets.

Specific types of cancer. Certain cancers such as leukemia or lymphoma can lower your platelet count. The abnormal cells in these cancers can crowd out healthy cells in the bone marrow, where platelets are made.

Less common causes of a low platelet count include:

Cancer that spreads to the bone. Some cancers that spreads to the bone may cause a low platelet count. The cancer cells in the bones can make it difficult for the bone marrow inside of bones to make platelets.

Cancer in the spleen. Your spleen is an organ in your body. It has several functions, including storing extra platelets. Cancer can make the spleen larger, so it may hold more platelets than usual. This means fewer platelets in your blood where they are needed.

How is a low platelet count diagnosed?

You will have regular blood tests when you have cancer to monitor your overall health. One test is called a platelet count. It checks the number of platelets in your blood, and shows if the count is low. A platelet count can be done as part of a blood test called a complete blood count.

You may have a platelet count test done more often if you have certain types of cancer or treatments that may cause blood or bone marrow problems.

How is a low platelet count treated?

During chemotherapy. If you have a low platelet count during chemotherapy, your doctor may decide to adjust your treatment. You might get a lower dose of chemotherapy or wait longer between treatment cycles. Your doctor may prescribe a drug called oprelvekin (Neumega). It helps prevent an extremely low platelet count.

Before surgery. If you are preparing for surgery and have a low platelet count, you may need to wait until your platelet counts are normal again to have the operation. This lowers the risk of heavy bleeding.

When platelet counts are very low, you may receive a transfusion. A transfusion of platelet cells into your blood can help prevent heavy or unexpected bleeding. However, this is a temporary treatment. The platelets from a transfusion only last about 3 days. If you have many transfusions, the platelets do not usually last as long each time.

Preventing bleeding when you have a low platelet count

When you have a low platelet count, take extra care to avoid situations that could cause bleeding. Here are some tips:

  • Ask your doctor before drinking alcohol or taking any new medication, including over the counter (OTC) pain relievers. These can make bleeding problems worse.

  • Use an extra soft toothbrush and brush gently. Do not floss if your gums bleed.

  • Blow your nose gently, using a soft tissue.

  • Be extra careful when using scissors, a knife, a needle, or other sharp tools.

  • Take precautions to avoid burns when you are cooking, such as by using oven mitts and avoiding skin contact with open flames, steam, hot water, or hot oil.

  • Shave with an electric razor.

  • Avoid contact sports and other activities that might cause injury.

  • Use a nail file with rounded ends to trim nails, instead of nail clippers.

  • Do not walk around with bare feet, inside or outside.

  • Think about whether there are ways to reduce your risk of falls at your home.

Be sure to talk with the cancer care team about other safety measures to take to avoid bleeding during the time you or a loved one has a low platelet count. And, ask them in advance what should be done if bleeding occurs, does not stop, or becomes worse. They may want you to call your doctor's office immediately. It may also be necessary to seek emergency medical care.

Questions to ask your health care team

  • Is a low platelet count a possible side effect for me?

  • Will I have regular tests to check for a low platelet count? How, and how often?

  • What signs of a low platelet count should I look out for?

  • If I experience signs of a low platelet count, should I tell the doctor right away?

  • What should I do to protect myself if I have a low platelet count?

  • How long should I follow these precautions?

  • When should I call the doctor if I start bleeding? What else should I do?

Related Resources

ASCO Answers Fact Sheet: Thrombocytopenia (PDF)

Bleeding Problems

Clotting Problems

Help People with Cancer: Donate Blood and Platelets

More Information

National Cancer Institute: Bleeding and Bruising and Cancer Treatment

ASCO answers; ThrombocytopeniaDownload ASCO's free Thrombocytopenia fact sheet. This 1-page printable PDF introduction to thrombocytopenia includes possible causes, symptoms, how it is diagnosed, treatment options, words to know, and questions to ask the health care team.