Some cases of chronic myeloid leukaemia (CML) are detected during blood tests carried out for another reason.
But you should visit your GP if you have worrying symptoms of CML, such as persistent tiredness, unusual bleeding or bruising, unexplained weight loss or night sweats.
Your GP will ask about your symptoms and may carry out a simple examination to check for other problems, such as swelling in one side of your tummy.
They may also send a sample of your blood to a laboratory so it can be checked for possible causes of your symptoms.
A very high level of white blood cells in your blood could be a sign of leukaemia. If this is detected, you'll be referred to a haematologist (specialist in blood conditions) for further tests.
To confirm a diagnosis of leukaemia, a sample of your bone marrow will need to be removed during a procedure called a bone marrow biopsy.
During a biopsy:
The procedure usually takes around 15 minutes and you should not normally need to stay in hospital overnight. You may have some bruising and discomfort for a few days afterwards.
Your bone marrow will be checked for cancerous cells and the cells will be analysed to identify which type of leukaemia you have and how advanced it is.
This can help your doctors determine the best treatment for you. Read about how CML is treated.