Your child will have a set of tests to confirm whether they have leukaemia or not. Your doctors diagnose leukaemia by looking at your child’s blood, their bone marrow and their genes. At any time, you can ask your healthcare team to tell you why your child is having a certain test and what the results mean.
Here are some of the common tests which children have to diagnose leukaemia. Your child might also have tests to help give doctors more information about the type of leukaemia they have.
Full blood count
A full blood count (FBC) measures the number of each type of cell in the blood: red cells, white cells and platelets. It also allows your child’s doctors to look for leukaemia cells in the blood.
Your child will have this test quite often throughout their treatment and you may wish to keep track of the results of their blood counts. If you choose to do this, your child’s consultant or specialist nurse will be able to explain what the results mean.
Bone marrow aspirate and trephine
Your child’s doctor will take a bone marrow sample to see how the blood is working inside your child’s bone marrow. Your child will have this test a number of times throughout their treatment. A small amount of bone marrow is taken from the pelvic bone using a needle (an aspirate). Your child’s doctors will then look at the bone marrow sample under a microscope.
Tests after diagnosis
If your child is diagnosed with leukaemia, the doctors will carry out a number of further tests. These will give them more information about the disease and help them decide on the best course of treatment for your child.
Leukaemia cells can sometimes get into the fluid that surrounds the brain and spinal cord (known as cerebrospinal fluid or CSF). A lumbar puncture involves taking a small sample of CSF to check if there are any leukaemia cells in it. Your child’s doctor will very carefully insert a needle between the bones of the lower spine into the space around the spinal cord and remove a few drops of CSF.
Cytogenetic analysis tests
These look for any abnormality in the chromosomes in your child’s leukaemia cells.
> Find out more about cytogenetic testing
Minimal residual disease (MRD) test
The test looks at a bone marrow sample and detects how many leukaemia cells remain in the bone marrow after treatment. When your doctors look at blood cells through a microscope, the lowest number of leukaemia cells they can detect is about one leukaemia cell in 20 normal cells.
The MRD test is much more sensitive and can detect leukaemia cells at levels as low as one leukaemia cell in 100,000 to one million normal cells. The results of the MRD test will help your doctors decide how much treatment your child needs.
Additional tests and scans
There are a number of other tests and scans your child may have throughout their treatment. These will help your doctors to see how the disease is responding to treatment, to look for any complications caused by the condition or its treatment, and to check for other problems such as infection.