What Is a Normal Platelet Count?

Platelets are tiny cells made in the bone marrow. Platelets are very important, as they prevent bleeding by forming clots and sealing blood vessels if they become damaged.

A normal platelet count ranges from 150,000 to 450,000 per microliter (mcL) of blood. Having too many or too few platelets may lead to complications.

Learn more about normal platelet count ranges.

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What Are Platelets?

Platelets are the cells in the blood that help prevent bleeding. These cells are made in the bone marrow. When a blood vessel becomes damaged, platelets are activated to stick together and to form a clot to seal the blood vessel wall to stop or prevent bleeding.

What Is a Normal Platelet Count?

The normal amount of platelets is 150,000 to 450,000/mcL of blood. 

What Does an Abnormal Platelet Count Mean?

An abnormal platelet count means there are too many platelets or too few platelets in the blood. 

High Platelet Count

A platelet count of over 450,000/mcL is called thrombocytosis. This can also be further classified into primary or secondary thrombocytosis, both of which are caused by the bone marrow producing too many platelets:

  • In primary thrombocytosis, there is a natural abnormality (such as a gene mutation) in the bone marrow cells that produce platelets. So, too many platelets are being made all the time.
  • In secondary thrombocytosis, there is no problem with the cells producing platelets. They are making too many platelets as a normal response to signals they receive due to another process going on somewhere else (such as iron deficiency or inflammation).

Symptoms of thrombocytosis may include abnormal bruising or bleeding or stroke-like symptoms. It is very common for no symptoms to be present at all. Having too many platelets can cause blood clots to form. This can actually lead to acquired von Willebrand disease, in which the platelets fail to interact properly with the blood vessel wall at sites of injury. The failure to seal the site of injury leads to bleeding.

Low Platelet Count

A platelet level of less than 150,000/mcL is considered low, and is called thrombocytopenia.

Platelet levels may be decreased for multiple reasons:

  • Bone marrow dysfunction: The bone marrow may not function properly and is not making enough platelets.
  • Enlarged spleen: Platelets may sit in the enlarged spleen and not be circulated out into the blood vessels.
  • Liver disease: This can cause platelet dysfunction and spleen enlargement.
  • Immune system destruction: Sometimes the immune system inappropriately sees platelets as foreign and destroys them. 
  • Medications: These may include chemotherapy, antibiotics, seizure medication, and blood thinners.

Symptoms of thrombocytopenia may include:

  • Bleeding, such as from the gums when brushing teeth or in the stool
  • Heavy menstrual cycles
  • Bruising
  • Petechiae, small red pinpoint spots of bleeding that may look like a rash

Having too few platelets can lead to bleeding, as there are not enough platelets to clot and repair blood vessel walls if they become damaged. 

How Is Your Platelet Count Tested?

Platelet counts are evaluated through a blood test called a complete blood count, or CBC. To run a CBC, a sample of blood is drawn. This blood sample is then put into a machine to count all the different types of cells in the blood. These include evaluating the size of the cells as well as the number. The size of platelets is referred to as the MPV, or mean platelet volume.

If the MPV is elevated, that means the platelets are larger than normal. An elevated MPV may be found in the following instances:

A decreased MPV means the platelets are smaller than normal. A decreased MPV can be found due to:

A Word From Verywell

If you are experiencing symptoms, such as bleeding or bruising, and are concerned about your platelet counts, be sure to talk with your healthcare provider about your concerns. A simple blood test can be done to make sure they are normal, and if not, further evaluation may be needed.  

Frequently Asked Questions

  • What is a normal platelet count?

    A normal platelet count for adults and children is between 150,000 and 450,000 platelets/mcL (microliter) of blood.

  • What causes a high platelet count?

    A high platelet count may be caused by abnormal stem cells in the bone marrow creating too many platelets. This refers to a condition called primary thrombocythemia, and its cause is unknown.

    In a condition called secondary thrombocytosis, a high platelet count is the result of another condition. Causes could include certain types of cancer, iron deficiency anemia, hemolytic anemia, inflammatory bowel disease, tuberculosis, and more.

  • How do normal platelet counts differ between men and women?

    Women tend to have higher platelet counts than men, possibly due to hormonal differences.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Johns Hopkins Medicine. What are platelets and why are they important?

  2. MedlinePlus. Platelet disorders.

  3. Cleveland Clinic. Thrombocytosis.

  4. National Heart, Lung, and Blood Institute. Thrombocythemia and thrombocytosis.

  5. Cleveland Clinic. Thrombocytopenia.

  6. National Heart, Lung, and Blood Institute. Thrombocytopenia.

  7. MedlinePlus. MPV blood test.

  8. Butkiewicz AM, Kemona H, Dymicka-Piekarska V, Matowicka-Karna J, Radziwon P, Lipska A. Platelet count, mean platelet volume and thrombocytopoietic indices in healthy women and men. Thrombosis Research. 2006;118(2):199-204. doi:10.1016/j.thromres.2005.06.021