Laboratory Tests

These are routine tests that are ordered to count the number and relative proportion of each of the different types of cells in the blood stream. They give your doctor information about the relative maturity of the blood cells present and they can provide the first evidence that a person has leukemia. Irregularities in cell counts, such as elevated WBC counts or low red blood cell counts may be due to leukemia or to a variety of temporary or chronic conditions, but blasts (very immature WBCs) are not normally seen in the blood. If they are present, some kind of leukemia is likely, and follow-up testing is indicated. The CBC and differential are used to help diagnose leukemia and are important tools to monitor the effectiveness of treatment and to detect recurrence.

Bone marrow aspiration/biopsy

Bone marrow exists as a matrix of fibrous supporting tissue, fluid, undifferentiated stem cells, and a mixture of blasts and maturing blood cells. If your doctor suspects leukemia, he will often order a bone marrow aspiration or biopsy to actually look at the fluid and tissue in the marrow. A pathologist, or other specialist then examines the marrow sample (bone and/or fluid) under the microscope, evaluating the number, size, and shape of each of the cell types, as well as the proportions of mature and immature cells. If leukemia is present, the type and severity of the disease can be determined.

For more information, see Bone Marrow Aspiration and Biopsy.

Spinal tap (lumbar puncture)

If leukemia is found in the bone marrow a spinal tap may also be done to look for leukemia cells in the cerebrospinal fluid.

Cytogenetic analysis by fluorescent in situ hybridization (FISH)

This is a molecular cytogenetic test used to investigate chromosomal abnormalities associated with leukemias, other cancers, and genetic disorders. It is used for diagnosis and differentiating the leukemias: there are translocations for acute myeloblastic leukemia (8;21), for promyelocytic leukemias (15;17), and for chronic myelocytic leukemia (9;22), among others. This technique can also detect deletions associated with AML or myelodysplastic syndromes (5q, 7q) and trisomies (trisomy 12) for chronic lymphocytic leukemia. FISH helps diagnose different leukemias that may look similar but have different genetic abnormalities and therefore may require different treatment.

Polymerase chain reaction (PCR)
This test uses DNA that is amplified by PCR to detect DNA mutations, inversions, or deletions that are associated with certain leukemias and may help with determining the prognosis for a certain leukemia. The better known PCR tests are for the promyelocytic leukemia M3 [PML-RARA t(15;17)(q22;21)], for acute myeloblastic leukemia [AML1-ETO t(8;21)(q22;q22) or inv(16)], and for chronic myelogenous leukemia (BCR-ABL t(19;22), but there are several others.

Non-Laboratory Tests

Computerized tomography (CT), magnetic resonance imagine (MRI), or positron emission tomography (PET) scans are sometimes used to look for signs of the disease (tumors and masses of cells) in areas such as the chest. Other imaging scans may also be used to evaluate the status of body organs such as the spleen, liver, and kidney.