Having tests for leukaemia can be a stressful time, and it helps when you know what to expect.
So we have some basic information for you, on the various tests that are used to diagnose leukaemia. You’ll also be offered tests during and after treatment, to see how well it’s working and as part of your follow-up care.
The most common tests include:
- Blood tests
- Bone marrow biopsy
- Genetic tests (including DNA and chromosome tests)
- X-rays and scans
- Lumbar puncture.
You may not have all of the tests we talk about here – it depends on the information your doctor needs in your individual situation.
Blood tests for leukaemia
Blood tests are important for diagnosing leukaemia, and for checking how well treatment is working.
A full blood count (FBC) uses a machine to see how many and what variety of white blood cells, red blood cells and platelets you have.
Depending on the type of leukaemia and what stage it’s at, this test may show too many white blood cells, or not enough of them.
If the leukaemia cells are taking over, your body may not be making enough red blood cells, which causes anaemia (making you feel tired). If your body is not making enough platelets, this may cause bleeding and bruising problems. You can read more in our information about blood cells and how they are made.
Your blood will also be examined under a microscope. This test is called a peripheral blood film or smear. When you have leukaemia, the test will usually show that many of the white blood cells are immature (these are called blasts).
Bone marrow biopsy
Your doctor may recommend a test to look at your bone marrow, because this is where your blood cells are made.
The results from this test are very useful, telling your doctor:
- Whether you have leukaemia
- What type of leukaemia it is, which determines the treatment
- How far it has progressed
- How well your treatment is working
- Whether you are still in remission (the cancer has gone after treatment).
Your doctor will need to take a sample of your bone marrow so it can be sent to the laboratory for examination under a microscope, and for genetic tests.
You go to hospital for this test. The bone marrow sample is collected through a needle that’s inserted into a bone: this is usually your pelvis.
Children are given a general anaesthetic so they sleep through the procedure. Adults usually have a local anaesthetic to numb the area, possibly along with nitrous oxide (‘gas and air’) and / or a sedative.
Unless you’re having inpatient hospital care at the time, it’s standard to go home the same day.
Genetic tests for leukaemia
There are different types of leukaemia, and it’s important to know which one you have so your doctor can recommend the best treatment.
Part of the answer is to test the leukaemia cells, found in your blood or bone marrow samples, for specific genes.
Genes – which are made up of DNA – regulate every cell in the body. Within your cells, genes are bundled into bigger packages called chromosomes.
In cancer cells, some of the genes may show abnormal changes, called mutations. Because of these genetic changes, the cancer cells don’t develop properly, and they multiply too fast.
One common genetic test looks for the BCR-ACL gene. This shows up in nearly all people with chronic myeloid leukaemia (CML) and some people with acute lymphocytic leukaemia (ALL). This gene usually creates an abnormality known as the Philadelphia chromosome, so this is a term you may also come across.
If the leukaemia cells have the BCR-ABL gene, a drug in the kinase inhibitor family may be recommended.
Leukaemia in general is not an inherited condition. But some genetic or inherited conditions may increase the likelihood of leukaemia developing. One example is Down’s Syndrome.
X-rays and scans
You may be offered an X-ray or one of these scans:
- MRI (magnetic resonance imaging)
- CT (computed tomography)
- PET (positron emission tomography).
Sometimes these tests are done to check whether the cancer has spread to other parts of your body. Another reason is to make sure your body is strong enough to start treatment. In this case, you may also be offered heart tests, including an electrocardiogram (ECG) and/or an echocardiogram (ultrasound scan of your heart).
With some types of leukaemia, it’s important to know whether the cancer has spread to the brain, and to prevent this from happening if possible.
So your doctor may need to collect a sample of cerebrospinal fluid, which bathes and protects your brain and spinal cord. The sample can be examined in the laboratory to see if any leukaemia cells are present.
You have this test in hospital. Before the test starts, the area is numbed with a local anaesthetic. Children are given a sedative as well, to help them stay calm and still.
You’ll be asked to lie in the best position, usually on your side with your legs curled up. The doctor inserts a thin needle between two of your spinal bones, and takes out a small amount of fluid. You’ll be advised to rest quietly for a while and then, if you’re not receiving inpatient care in hospital, you can usually go home the same day.
Some people have a headache or backache afterwards. This will settle eventually and you’ll get advice on taking painkillers if needed, any problems to look out for, and how long to rest.