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Laboratory tests

Full blood count and differential
These are routine blood tests that are ordered to check the number and relative proportion of cell type (red blood cells (RBC), platelets, white blood cell (WBC)) in the blood stream. They can provide the first evidence that a person has leukaemia. Abnormal cell counts, such as elevated WBC or low RBC counts may be due to leukaemia or a variety of temporary or chronic conditions. However, blasts (very immature WBCs) are not normally seen in the blood. If they are present, some kind of leukaemia is likely, and follow-up testing is indicated. They are also used 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 leukaemia, he/she will often order a bone marrow aspiration and biopsy to actually look at the fluid and tissue in the marrow. A pathologist or haematologist 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 leukaemia is present, the type and severity of the disease can be determined.

Flow cytometry
Leukaemic cells may appear similar under the microscope. Flow cytometry is able to examine the markers on a cell. Millions of cells can be analysed by this method. This helps to determine the cell types and number of abnormal cells.  

Cytogenetic analysis and/or fluorescent in situ hybridization (FISH)
These specialised genetic tests are used to investigate chromosomal abnormalities. It is important for diagnosis, classification, treatment decision, prognosis and monitoring of leukaemia. One example is t(15;17) for acute promyelocytic leukaemia where chromosome 15 and 17 are translocated (fused) together. 

Polymerase chain reaction (PCR)
This test uses DNA to detect specific changes that are associated with certain leukaemias. It is often used in conjunction with cytogenetics/FISH. Very small amount of disease can be detected using this technique, enabling monitoring of minimal residual disease (MRD), which can be important to guide treatment decisions. Examples are PML-RARA in acute promyelocytic leukaemia and BCR-ABL in chronic myelogenous leukaemia. 

Lumbar puncture (spinal tap)
This is sometimes performed to look for leukaemic cells in the cerebrospinal fluid (CSF), which usually circulates around the spinal cord and brain. This is particularly important for some leukaemias and to guide specific therapy as the conventional chemotherapy does not usually penetrate the CSF well.  

Non-laboratory tests

Computerised tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET) scans are sometimes used to look for signs of the disease in other areas such as lymph nodes, liver and spleen. Other imaging scans may be used to evaluate the organ function such as heart, liver and kidneys.

Last Review Date: September 3, 2015