Leukemia is a cancer that occurs in the blood-forming (lymphoid) cells in the bone marrow, a spongy tissue found inside bone cavities. The cancer begins when blood cells undergo harmful changes that cause them to grow uncontrollably. Eventually, the abnormal cells will crowd out the healthy blood cells.

The symptoms of leukemia can include fatigue, easy bruising and bleeding, frequent infections and enlarged lymph nodes. Treatment can vary based on the type and stage of the cancer but may include chemotherapy, radiation therapy, targeted therapy or CAR T-cell therapy.

Laboratory tests used for diagnosing leukemia

If leukemia is suspected based on the symptoms, such as enlarged lymph nodes or pale skin (which could indicate anemia), a physician will typically perform a physical examination and order lab testing, such as:

Complete blood count (CBC)

Often the first test performed in the diagnostic process for leukemia, a CBC can provide valuable information about blood cells. An abnormality in a blood cell count, such as low red blood cells (anemia), low platelets (thrombocytopenia) or high white blood cells (leukocytosis), may indicate leukemia.

Peripheral blood smear (PBS)

Unlike a CBC, which uses a machine to analyze a blood sample, a PBS involves a microscopic analysis of the blood cells by a pathologist. A physician may order a PBS to follow up on a CBC that revealed an abnormal blood cell count. The result may help the physician determine the reason for the abnormality.

Cytogenetic analysis

Samples of tissue and fluid are collected through blood or bone marrow testing and then microscopically examined by a cytogeneticist, who can identify chromosome changes. Cytogenetic analysis can detect chromosome alterations and, in some cases, may identify the genes affected.

Flow cytometry

During flow cytometry, cells in a blood sample are stained with a fluorescent dye and passed through a laser beam. The dye causes the cells to emit light, which is measured by a detector.

Flow cytometry is a sensitive technology that can help a physician determine the cell types present in the sample and identify specific protein markers on the surface of the cells. The physician can use the markers to differentiate between healthy and cancerous cells and, if leukemia is diagnosed, classify its type.

Procedures used for diagnosing leukemia

The gold standard in diagnosing leukemia is:

Bone marrow biopsy

To perform a biopsy, a physician will insert a long, thin needle into the hip bone or another large bone and withdraw a small sample of bone marrow. The sample will be sent to a lab for microscopic examination by a pathologist, who can identify abnormalities in the number, size and appearance of the cells.

Often performed if other diagnostic tests, such as a CBC and flow cytometry, suggest leukemia, a bone marrow biopsy can help the physician confirm the diagnosis, determine the type and subtype of leukemia and assess the extent of the cancer. The results can be used to guide treatment decisions and determine the prognosis.

Imaging tests used for diagnosing leukemia

While imaging is not used to directly diagnose leukemia, a physician may order imaging tests to determine whether leukemia cells have spread and check for complications, such as lymph node enlargement and organ involvement. Some options include:

Chest X-ray
Computed tomography (CT) scan
Magnetic resonance imaging (MRI) scan
Positron emission tomography (PET) scan
Ultrasound scan

Frequently asked questions (FAQs) about the diagnostic process for leukemia

The following FAQs-related articles provide additional information about the diagnostic process for leukemia:

Benefit from world-class care at Moffitt Cancer Center

If you would like to learn more about the diagnostic process for leukemia, you can request an appointment with a specialist in Moffitt’s comprehensive Malignant Hematology Program by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.

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