The results of a blood count can help diagnose or manage leukemia. They can also show how well your current treatment is working.

Leukemia is a type of blood cancer that begins in the bone marrow, where many blood cells are made. If you have leukemia, you may not make enough of some kinds of blood cells.

This cancer can also cause abnormal blood cells to form, crowding out other healthy blood cells in the bone marrow and spilling into the bloodstream.

Getting tested to find out your specific blood counts is important for diagnosing and managing leukemia.

Leukemia mainly affects white blood cells called lymphocytes. These immune cells help your body fight off infections.

When someone has leukemia, their body makes larger, abnormal cells called leukemic cells instead of lymphocytes and other necessary cells like red blood cells (to carry oxygen) and platelets (to help blood clot). This is why leukemia can cause symptoms like fatigue or excessive bleeding and bruising.

A healthcare professional may order a complete blood count test as a part of your routine medical checkup. This is because blood counts can tell a lot about your health. For example, too many white blood cells and too few red blood cells or platelet cells may mean that you have leukemia or your leukemia is not well-controlled.

Types of leukemia

Different kinds of leukemia affect blood cell counts in different ways. They may also require different kinds of treatment. There are four main types of leukemia:

  • Acute lymphocytic leukemia (ALL): ALL is acute (sudden and fast) leukemia. It is more common in adults over age 70 and more common in men than in women. In ALL, the damaged cells, called leukemic lymphoblasts, multiply rapidly.
  • Acute myeloid leukemia (AML): AML is the other main type of acute (sudden and fast) leukemia. The abnormal cells in AML are white blood cells called myeloblasts.
  • Chronic lymphocytic leukemia (CLL): The most common chronic leukemia in adults, CLL occurs more frequently in men than women. Like ALL, CLL is also caused by the production of leukemic lymphoblasts. However, CLL typically progresses much more slowly.
  • Chronic myeloid leukemia (CML): CML is more common in older adults (over age 65) and in men. It rarely occurs in children and younger adults. It is also caused by an often slow-growing production of myeloblasts.
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Typical blood cell counts vary by age and gender. They can also temporarily change depending on whether you recently had a bad flu, infection, or even injury. The healthy blood cell ranges are shown in the table below per microliter (μl):

Platelets (μl)Red blood cells (μl)White blood cells (μl)
Children150,000–400,000 million4–5.5 million5,000–10,000
Females assigned at birth (FAABs)150,000–400,000 million4.2–5.4 million4,500–11,000
Males assigned at birth (MAABs)150,000–400,000 million4.7–6.1 million5,000–10,000

What CBC results indicate leukemia?

If you have leukemia, your blood cell count may show higher than usual levels of white blood cells, which include leukemic cells.

However, you may also have a lower reduced number of white cells (leukopenia), red blood cells (anemia), or platelets (thrombocytopenia). If all three types are low, this is known as pancytopenia or cytopenia as follows per liter (L) or in grams per deciliter (g/dL).

Platelets (per L)Red blood cells (hemoglobin, g/dL)White blood cells (neutrophils, per L)
Females assigned at birth (FAABs)<150 × 109 /L<12 g/dL <1.8 ×109 /L
Males assigned at birth (MAABs)<150 × 109 /L<13 g/dL<1.8 ×109 /L

That said, any value for these markers that’s outside of the healthy range can be considered leukemia if your doctor cannot find a different cause for it, such as infection, for example. Your exact values also depend on the type of leukemia you have.

If you have higher than healthy levels of white blood cells and low counts of red blood cells and platelets, the doctor will order additional tests to get more information.

If you’re having symptoms, this might reinforce the doctor’s suspicion. These may may include:

If you have any or all of these symptoms, you may need certain imaging tests, including:

Your leukemia treatment plan will take several factors into consideration, such as your:

  • type of leukemia
  • age
  • overall health
  • spread of leukemia to organs
  • response to initial treatment

Your doctor will let you know how often you’ll need to return for more blood tests. If you are diagnosed with leukemia, you may need regular physical exams and blood tests, so your doctor can watch for signs of disease progression or remission.

How well treatment is working

Regular leukemia blood count tests, such as complete blood count, are very important in the treatment process because they can help show:

  • how well leukemia treatments are working
  • side effects of leukemia
  • side effects of leukemia treatments
  • if you need changes in your treatment

If additional treatments are needed

Leukemia blood cell counts also help to show whether you need additional treatments. For example:

  • If you have low red cell counts, you may have anemia, which causes low energy levels. Your doctor may recommend treatment for anemia, such as iron supplements or a blood transfusion.
  • If you have low white cell counts and a fever, you may have an infection and need antibiotics.
  • If your platelet counts are too low, you may have an increased chance of life threatening bleeding. Your doctor may recommend platelet or blood infusions to lower this risk.

Leukemia is a type of blood and bone marrow cancer. You may not notice symptoms for a long time, if at all. This is why a complete blood count test can help show imbalances in your blood cells.

Different types of leukemia can cause your blood cell counts to be higher or lower than expected. If you have been diagnosed with leukemia, blood cell count tests can also indicate how well your treatment is working and if adjustments are needed.