Because leukemia is a blood cancer, it can affect a person’s platelet count. People with leukemia sometimes have a low platelet count. However, other conditions can also cause low platelets.

Leukemia is one of the most common forms of cancer in the United States. The disease occurs when blood cells grow atypically. Specific blood tests can help doctors determine whether someone has leukemia.

This article looks at how leukemia can affect a person’s platelet count. It will also discuss typical and atypical platelet counts and related blood tests.

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Platelets are incomplete cells that float around the blood in a person’s body. Their primary function is to stop bleeding in response to injured blood vessels. A person’s platelet count is the number of platelets they have per volume of blood.

A 2022 review explains that a typical platelet count lies between 150,000 platelets per microliter (mcL) and 450,000 platelets per mcL.

According to the Leukemia and Lymphoma Society, most individuals will typically fall into a range that remains the same across all individuals, no matter their sex or age.

Doctors consider any platelet count above 450,000 platelets per mcL to be high and define this as thrombocytosis. In contrast, they consider any platelet count below 150,000 platelets per mcL low, referring to this as thrombocytopenia.

Having a low platelet count could mean a person has leukemia. However, other conditions can also cause thrombocytopenia. Moreover, a person with leukemia can have a typical platelet count.

The table below details the typical ranges for a person’s platelet count.

Typical platelet count
Children150,000 to 450,000 platelets per mcL
Adults150,000 to 450,000 platelets per mcL

Learn more about leukemia.

A complete blood count (CBC) is one of the most common tests that doctors perform. This test determines the number and concentration of various blood components, from hemoglobin to different blood cells. CBCs can provide accurate platelet counts and involve taking a person’s blood sample and analyzing it in the laboratory.

To take a blood sample, a healthcare professional prepares a needle and syringe, then finds an accessible vein, often in the forearm. They will sometimes use a tourniquet to make the vein more prominent. They will then insert the needle into this vein before withdrawing a small amount of blood with the syringe.

A person may experience a small amount of pain when the needle enters their vein. Some pain may persist afterward, but this is temporary. The sample will then go to a laboratory for analysis.

Learn more about blood tests.

Doctors may suspect leukemia if someone’s CBC results show a low platelet count. However, the results do not provide enough information for doctors to diagnose leukemia.

Low platelet counts can occur for many reasons, including:

  • HIV
  • hepatitis C
  • nutrient deficiencies
  • pregnancy
  • taking certain medications

For this reason, doctors typically request further tests to diagnose leukemia. These tests include:

Other standard diagnostic tests include peripheral blood smear evaluations and bone marrow biopsies.

If these tests show that someone has leukemia, doctors will recommend treatment.

The treatment plan will depend on the type of blood cancer and whether the disease has spread. However, this strategy almost always involves a pharmacological component.

A person’s platelet count can make a difference in what treatment they receive. A 2022 study suggests that chemotherapy is less effective in people with 70,000 or fewer platelets per mcL.

This is because chemotherapy can reduce platelet counts, increasing the risk of severe bleeding. Many doctors, therefore, do not recommend chemotherapy for people with very low platelet counts.

Here are some frequently asked questions regarding platelet count and leukemia.

What is the minimum platelet count for chemotherapy?

Many doctors consider 70,000 platelets per mcL the minimum safe platelet count for chemotherapy.

What would a CBC look like with leukemia?

Leukemia can sometimes cause a low platelet count, which experts define as 150,000 platelets per mcL.

Leukemia is a cancer of the blood. It can decrease a person’s platelet count to less than 150,000 per mcL. Experts consider this a low platelet count, regardless of age or gender.

Blood tests, such as a CBC, can determine someone’s platelet count. However, platelet count alone is not enough to diagnose leukemia. Additionally, some people with the disease may not experience a change in platelet count. For this reason, doctors must rely on other methods to diagnose leukemia.

People with low blood counts are more prone to bleeding. Since chemotherapy can reduce platelet counts, most doctors will not use chemotherapy to treat people with leukemia with very low platelet counts.