man being diagnosed for leukemiaShare on Pinterest
Getty Images/Jose Luis Pelaez

Leukemia is a cancer of bone marrow stem cells; the cells that develop into white blood cells, red blood cells, or platelets. In 2021, more than 61,000 people are expected to be diagnosed with leukemia. There are many different types of leukemia, and an accurate diagnosis is crucial for effective treatment.

Diagnosing leukemia is often a multi-step process. Read on for more information about how this cancer is diagnosed and what to expect.

Leukemia is a broad term — there are actually several different types of this condition. Leukemia can be “acute — sudden onset” or “chronic — slow onset.”

What leukemia is

Leukemia is a blood cancer. Although there are different kinds of blood cells, leukemia is typically a cancer of the white blood cells. White blood cells are part of your immune system and help protect you from illnesses and other infections.

Types of leukemia

There are four main types of leukemia. They include:

  • Acute lymphocytic leukemia (ALL). ALL is the most common form of childhood cancer, but it can also occur in adults. It causes too many white blood cells known as lymphocytes to develop.
  • Acute myelogenous leukemia (AML). AML causes white blood cells to become abnormal. These abnormal white blood cells also reproduce too quickly.
  • Chronic lymphocytic leukemia (CLL). CLL affects B lymphocytes, or B cells, that help your body fight infections. It’s the most common type of leukemia in adults.
  • Chronic myelogenous leukemia (CML). Starting in your bone marrow, CML causes a high number of a type of white blood cells called granulocytes. It’s also associated with gene mutations called Philadelphia chromosomes.

After the type of leukemia is confirmed, the medical team will then determine the stage of leukemia, which is based on the number of cancerous white blood cells that are circulating in an individual’s body.

Read this article for more information about staging leukemia.

In order to diagnose leukemia, a doctor may use a variety of diagnostic tools. These tests may include:

A doctor performs a physical exam to check for any swollen lymph nodes, as well as swelling in the spleen or liver. They may also check for symptoms like bone or muscle pain, tenderness, and easy bruising.

Documenting and reviewing a person’s medical history is also important for other symptoms like unexpected fatigue, unexplained weight loss, night sweats, and fevers. Based on the exam and your medical history, your doctor will be able to order the most appropriate medical tests.

Since leukemia is a cancer of the blood, blood tests can tell doctors a lot about what’s going on and is typically the first test a doctor will run if they suspect leukemia.

Blood tests that may be performed

Blood tests to diagnose leukemia may include:

Complete blood count (CBC)

For this test, blood is drawn and examined under a microscope to observe the different kinds of blood cells, their shape, and how many there are of each.

CBC measures the amount of red blood cells, white blood cells, platelets, and levels of hemoglobin and hematocrit, giving a general overview of your health.

Peripheral blood smear

This test may be done if the CBC is abnormal or not definitive. In this test, a drop of blood is spread on a glass slide and examined.

By reviewing this “smear,” lab technicians can determine if each kind of blood cell is normal in appearance and number. It also lets them calculate the proportion of each kind of white blood cell in relation to the total white blood cell count

What do the results mean?

In a CBC, the range of “normal” can vary slightly between each lab’s scale or measurement method. Your doctor will explain what your results mean.

Leukemia causes high levels of white blood cells and can cause low levels of platelets and hemoglobin. A CBC can show all of these counts and provide other important information.

A peripheral blood smear can show immature or abnormal cells, which may be a sign of leukemia and signal the need for more testing.

Leukemia may affect the blood cells as they are produced in the bone marrow. Sometimes changes in blood cells may be seen in the bone marrow before they’re obvious in the blood. Some leukemias are present in bone marrow only and aren’t identifiable in blood.

A bone marrow biopsy or aspiration can look at the fluid and tissue in your marrow, seeing if cancer cells are present.

How it’s done

The biopsy is usually taken from your hip bone. The area is numbed and the doctor uses a hollow needle to take a small amount of marrow (aspiration) and a small piece of bone (biopsy). You might have discomfort or pain after the procedure for a few days.

What do the results mean?

The samples are examined under a microscope to look for any chromosomal changes, genetic markers, or leukemia cells, which are immature white blood cells that rapidly multiply in individuals who have leukemia.

Cytochemistry tests involve putting cells on a slide and exposing them to chemical stains or dyes. These dyes only react with certain types of leukemia cells, genes, or chromosomes. This can help doctors differentiate what kind of leukemia is present and look for specific changes in these cells.

Genetic tests

Different tests can include:

  • Cytogenetics. This is molecular/genetic testing that evaluates some of the liquid tumor for chromosomal abnormalities or cellular abnormalities.
  • Fluorescent in situ hybridization (FISH). This technique can be used on blood or bone marrow samples. It uses fluorescent dyes that attach to certain genes or chromosomes, allowing doctors to see specific gene changes under a microscope.
  • Polymerase chain reaction (PCR). Similar to FISH, this sensitive DNA test looks for specific single gene changes and not overall chromosomes.

What do the results mean?

These tests examine genetic material. Certain types of leukemia may include abnormal chromosomes or changes in chromosomes. For example, some individuals with ALL and CML have a translocation, where two chromosomes swap DNA.

This usually occurs between chromosome 22 and chromosome 9. It’s known as the Philadelphia chromosome, and there are specific treatment options for people with ALL who have this chromosomal change.

If genetic material is missing, it’s known as a deletion. Some people with CLL have a chromosomal deletion in chromosomes 11, 13, or 17. They may also have a translocation on chromosomes 11 and 14 or an extra copy of chromosome 17.

This information is used to develop a treatment plan.

Leukemia doesn’t typically form tumors, so imaging tests aren’t as helpful in diagnosis as they may be with other types of cancers. They may be used to see if cancer has spread beyond the bone marrow and blood or to see if there are any infections or other problems caused by cancer.

There are limited studies about using imaging for monitoring leukemia, and more research is needed.

Imaging tests that may be performed

There are a variety of different imaging tests that may be performed when diagnosing leukemia. These can include:

  • X-ray. This test may be done to check for enlarged lymph nodes or if a lung infection is suspected.
  • CT scan. This test uses X-rays and a computer to make cross-sectional images of the body. It may be combined with a PET scan to show any swollen organs or lymph nodes.
  • Magnetic resonance imaging (MRI). This test creates detailed pictures of the inside of the body using radio waves and strong magnets. These images can be helpful in showing the brain and spinal cord. An MRI is often done if a lumbar puncture has found leukemia cells in cerebrospinal fluid.
  • Positron emission tomography (PET). This test is similar to a CT scan, but it involves injecting a radioactive sugar that’s taken up by cancer cells, making them show up on the images.

How they are done

These tests use X-rays, sound waves, magnetic fields, or radioactive particles to help develop pictures of the inside of the body. They’re non-invasive, although sometimes a contrast dye may be injected into a vein to help certain cells or organs show up better on the images.

What do the results mean?

These tests aren’t used much in diagnosing leukemia since tumors don’t generally form. But they are helpful in diagnosing infections, monitoring the spread of cancer by looking for swollen lymph nodes and organs, and when used in conjunction with other diagnostic tools.

There are several other tests that may be performed during the diagnostic process, as well as when trying to figure out the extent of the disease. These can include a lumbar puncture, also known as a spinal tap. This test can check for leukemia cells in the cerebrospinal fluid (CSF).

A lymph node biopsy also might be done. This test can check for leukemia cells in the lymph nodes. It’s helpful in seeing where leukemia has spread and can provide information about other symptoms that may occur because of swollen lymph nodes.

How they are done

In a lumbar puncture, you lay down on your side with your knees pulled up to your chest. Your lower back is numbed. The doctor inserts a needle between two vertebrae in your lower back, into the spinal canal. Spinal fluid pressure is measured and a small sample of CSF is removed.

There are different kinds of lymph node biopsy:

  • Needle biopsy. A needle is used to draw out some lymph to send to the lab.
  • Open biopsy. Part or all of your lymph node is removed.
  • Sentinel biopsy. This is done if you have cancer. If cancer is in the sentinel lymph nodes, the nodes close to the cancer site, it’s more likely to spread to certain areas.

What do the results mean?

A lumbar puncture can tell whether leukemia has spread to the central nervous system. This will impact treatment and prognosis.

Lymph node biopsies may explain symptoms a person is having. For example, if lymph nodes in the chest are swollen because of cancer, it may cause problems breathing. Knowing where cancer has spread can help with treatment and symptom relief.

Diagnosing leukemia is often a multi-step process with a variety of tests. Getting an accurate diagnosis of the type of leukemia as well as any specifiers is important since this will help determine the course of treatment.