When to worry about a high platelet count

plateletsAlso known as platelets, are cells in the blood that help blood clot. Clotting blocks the walls of damaged blood vessels to prevent bleeding. Platelets are made in the bone marrow, the spongy tissue inside the bones of the body.

The normal number of platelets in a blood sample is about 150,000 to 450,000.Platelet levels greater than 450,000 are called thrombocytosis.

While elevated platelet levels can indicate an underlying disease, it’s not always serious.

This article explains what may trigger high platelet levels. It will also cover potential complications, diagnostic methods and treatment options.

What is the difference between primary and secondary thrombocythemia?

The two types of thrombocytosis are essential thrombocythemia and secondary thrombocythemia:

  • In essential thrombocythemia – also known as essential thrombocythemia– Bone marrow makes too many platelets. This may be caused by mutations or genetic changes in two specific genes, the JAK2 gene and the CALR gene.
  • Secondary thrombocytosis, also known as reactive thrombocythemia, occurs when platelets become elevated due to a condition, infection, medication, or bleeding.

Is a high platelet count always serious?

Many times, a high platelet count does not cause any symptoms. It may just be found through a routine blood test. While the cause of high levels should be investigated, it is not always due to something dangerous or serious.

Platelets can be raised by medications, infections, low iron levels, or exercise.

What are the potential complications?

People with elevated platelets usually do not have any complications. However, some people with high platelet counts develop blood clots.

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Blood clots can form in any blood vessel. Most commonly, they form in the blood vessels or the brain in the arms and legs. These clots prevent the normal flow of blood through these vessels. This reduced blood flow can cause symptoms such as:

  • headache
  • Dizziness
  • stroke, which is a medical emergency that occurs when a blood clot prevents the brain from getting enough oxygen
  • throbbing or numbness
  • Seizures, which are medical emergencies that occur when brain cells suddenly become overactive

Talk to your healthcare provider if you have elevated platelets and are concerned about your risk of blood clots.

blood cell cancer

Essential thrombocythemia has the potential to become a type of cancer called acute blood cell cancer leukemia. Remember that this is very rare.

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other cancers

One cause of secondary thrombocytosis may be cancer. Thrombocytosis can sometimes be one of the first symptoms of cancer.

The most common cancers that cause elevated platelets include ovarian, lung, and breast cancers. Elevated platelets can also be seen in gastrointestinal cancer, which refers to cancer anywhere in the digestive tract, and lymphoma, which is cancer found in blood vessels that carry fluid from tissues and cells throughout the body.


A high platelet count can lead to blood clots. This can trigger uncomfortable symptoms, as well as medical emergencies such as seizures or strokes. Other complications include acute leukemia and other cancers.

What are healthcare providers looking for?

When evaluating the cause of elevated platelets, a healthcare provider may look for symptoms such as bruising, bleeding, signs of infection, or other underlying medical conditions.

Blood tests or imaging may be done. These tests may include:

  • The iron plate shows how much iron is present
  • Complete blood count, which is a complete blood panel that includes white and red blood cell counts
  • C-reactive protein and Erythrocyte sedimentation rate blood test Look for inflammation, which will indicate if the body is trying to recover from an infection or injury
  • blood tests to check for specific gene mutations
  • Bone marrow biopsy, where a sample of bone marrow is removed for evaluation
  • mammogram, an imaging test to check for breast cancer
  • Upper gastrointestinal endoscopy, which is a procedure in which a small tube with a camera is inserted into the mouth and down into the stomach to check for cancer in the upper gastrointestinal tract
  • colonoscopy, a procedure that uses a small tube with a camera inserted into the rectum to check for gastrointestinal cancer in the large intestine

How do you treat high platelet counts?

Treating a high platelet count starts with finding the underlying cause. In some cases, such as if a person has no symptoms, treatment may not be needed.

Treatment for essential thrombocythemia may include certain drugs that slow the production of platelets. In secondary thrombocythemia, treatment of the underlying disease (such as an infection) may be all that is needed to reduce elevated platelets.


Treatment for high platelet counts will vary depending on the underlying cause, but may include medication.

What is the outlook for people with high platelet counts?

Elevated platelet counts may be associated with cancer. One study reported that about 11 percent of men with high platelets and about 6 percent of women with high platelets had cancer.

Remember that most elevated platelet counts are caused by a reactive process, such as infection or inflammation. Platelet counts usually return to normal once the underlying cause is resolved.


Elevated platelet levels or thrombocytosis is not always a sign that something serious is going on. Sometimes high platelet levels are triggered by infections, medications, low iron levels, or physical activity.

High platelets don’t always cause symptoms, but some people may develop complications such as blood clots and certain cancers.

Treatment for elevated platelet levels will vary based on the underlying cause.

Frequently Asked Questions

  • What does a high platelet count mean?

    A high platelet count means that there are more platelets in the blood than normally found. Platelets are blood cells that help blood clot and prevent bleeding.

  • What is considered a high platelet count?

    A normal platelet count is between 150,000 and 450,000. A high platelet count is any number above 450,000.

  • What causes a high platelet count?

    High platelet counts can be due to bone marrow dysfunction or other causes such as infection, inflammation, bleeding, or cancer.

  • Which cancers cause high platelet counts?

    Cancers that can cause elevated platelets include:

    • lymphoma
    • breast cancer
    • lung cancer
    • ovarian cancer
    • Gastrointestinal cancer