Having a blood test means having a sample of blood taken so that it can be tested in a laboratory. Blood contains many chemicals and proteins as well as blood cells. Blood tests can help doctors find out more about your general health and how your body is affected by the lymphoma and your treatment.
You are likely to have regular blood tests as part of your diagnosis, throughout your treatment and as part of your follow-up.
Blood tests are done to:
- help diagnose a few types of lymphoma (a biopsy is needed to diagnose most lymphomas)
- find out more about the lymphoma before treatment is planned
- check your general health before or during treatment
- assess how your treatment is affecting you
- check whether you have recovered enough from one cycle of treatment before starting the next one
- monitor the lymphoma and your general health during follow-up after treatment and during any periods of active monitoring (or ‘watch and wait’).
Blood tests are done frequently as part of diagnosis and treatment. They are useful in giving your medical team important information about how your body is responding to the lymphoma and its treatment. If you are in follow-up, you are likely to have blood tests at your check-ups but less frequently than you did before. The lymphoma and its treatment can cause frequent changes in your blood results. Your blood test results should be more stable when you are in follow-up, so less frequent tests are needed.
If you are not already in hospital, your doctor can tell you where and when to go for the test. Many hospitals have a department for taking blood samples so your doctor might ask you to go there when it is convenient for you. Many blood-taking departments are ‘drop-in’– you do not need an appointment. You might be asked to have blood tests before a clinic appointment or to arrive early for a clinic appointment so blood can be taken before you see your doctor. Sometimes, blood tests can be done at your GP surgery.
If you are on a day care unit having treatment or you are staying in hospital, blood tests are usually taken on the unit or ward.
How should I prepare?
Many blood tests do not need any special preparations. Sometimes you might need to fast (not eat anything or drink anything other than plain water) for a certain amount of time before your test. You might need to stop certain medicines or avoid particular foods. If you are not sure whether you need to do anything before your blood test, ask your medical team for advice before your test.
What happens during the procedure?
A nurse or phlebotomist (someone trained to take blood) takes the sample. Blood is taken from a vein close to the surface of your skin. Most blood tests are taken from the arm, often from the inside of the elbow. You might have it taken from another part of your body if the veins inside your elbow are not suitable.
A tight band is usually put around your upper arm to slow down the flow of blood. This makes the vein swell so it is easier to take the blood.
A needle is put into your vein. This might feel like a ‘sharp scratch’ but only lasts a moment. Tell the nurse if you are uncomfortable. A small container is attached to the needle to collect the blood. Several containers might be needed to collect samples for different tests. Only small amounts of blood are taken for each sample.
When the samples have been collected, the needle is removed. The nurse usually puts a cotton wool pad on the site and presses to stop the blood flowing. The cotton wool pad might be secured with tape or you might have a plaster put on.
If you have a central line or peripherally inserted central catheter (PICC) line, it might be possible to take the sample through your line.
What happens after the procedure?
If you are an outpatient, you can usually go straight home after the test unless you need to stay at the hospital for an appointment or treatment.
A blood test is usually a very safe procedure with no after effects. You might have a slight ache and get a small bruise at the site where the sample was taken from. These problems get better on their own. The risk of infection is very small but seek medical advice if you are worried; for example, if you develop pain or swelling at the site.
Rarely, you might feel faint during a blood test. Tell the person taking the blood if you feel this way. You might have to lie down until you feel better.
It can take anywhere from a few minutes to a couple of weeks to get the results of your blood test, depending on what tests are done on the sample. Your medical team can advise you when to expect your tests results. Waiting for test results can make you feel anxious but your medical team are gathering important information at this time so they can give you the best possible treatment.
Your medical team should tell you if your blood test results are normal or if there are any problems. You can ask to see your results, but they can be difficult to interpret. Do not be alarmed if your test results seem to be outside the reference range. Many people have results outside the reference ranges that are not a cause for concern. Your medical team consider your individual circumstances when they look at your blood test results to decide what the results mean for you. Factors they might consider include results from other tests and knowledge of any medical conditions you have. They can explain what your test results mean. Ask your medical team if anything about your results concerns you.
What is a ‘reference range’?
When blood test results come back from the laboratory, they are reported together with a ‘reference range’ (or ‘normal range’). Most people’s results are within the reference range. Around 1 in 20 healthy people have results outside the reference range. Many factors can influence your blood test results, for example, age, sex or ethnicity.
Lab Tests Online have information on reference ranges for many common blood tests. However, blood tests are not done in the same way in all laboratories. Laboratories might have slightly different reference ranges, use different techniques or might use different units to report their results. Your medical team are best placed to advise about your blood test results as they know your individual circumstances.
There are many different blood tests used for people with lymphoma. The most common is the full blood count.
The full blood count (FBC) is a test that measures how many blood cells there are in your blood. The number of each type of blood cell is often called the ‘count’.
Blood cells are made from blood stem cells in your bone marrow (the spongy tissue in the centre of your bones). Stem cells are basic cells that can develop into more specialised cells. Blood stem cells can become:
- white blood cells, which fight infection as part of your immune system
- red blood cells, which carry oxygen around your body
- platelets, which help your blood to clot, preventing bruising and bleeding.
New blood cells are released from the bone marrow into the bloodstream.
Why is the full blood count done?
A FBC checks for low blood counts. It also measures how much haemoglobin there is in the blood. Haemoglobin is a protein in red blood cells that carries oxygen around the body. Further tests on the blood, such as what the blood cells look like under the microscope, can give other useful information.
Possible low blood counts include:
- anaemia - a low count of red blood cells or a low level of haemoglobin in the blood
- thrombocytopenia - a low platelet count
- neutropenia - a low count of a type of white blood cell called a neutrophil.
Other types of white blood cell might be low too.
You can develop low blood counts for several reasons:
- lymphoma in your bone marrow takes up space needed for healthy blood cells and blood stem cells
- some treatments stop your bone marrow from working properly as they affect both lymphoma cells and healthy blood stem cells
- some types of lymphoma cause antibodies to form that attack your own healthy blood cells; this is called ‘autoimmunity’.
If you have low blood counts due to the lymphoma, treatment for the lymphoma can help your blood counts recover. Monitoring your blood if you are on ‘watch and wait’ can help your medical team decide when you need to start treatment.
The FBC is a very important blood test when you are on treatment as most treatments for lymphoma can cause low blood counts. These treatments include chemotherapy, antibody therapy and many targeted drugs. Radiotherapy does not usually cause low blood counts unless a large area of your bone marrow is being treated.
If you are having chemotherapy or antibody therapy, your blood counts usually begin to recover a week or two after each treatment. Your medical team monitor your FBC after each treatment to make sure your blood counts are at a safe level for you to have your next planned dose of treatment. If your blood counts are too low, your treatment might be delayed until they recover. Your blood counts usually recover on their own in time but some people are given supportive treatments like growth factors to help boost blood counts.
If you are having a newer drug that you take every day, you have regular blood tests to check how you are responding to the treatment.
Many other blood tests are used for people with lymphoma. For example, they can be done to find out:
- how well your liver and kidneys are working
- whether you have any signs of inflammation by measuring substances in the blood, such as lactate dehydrogenase (LDH) or C-reactive protein (CRP) and by measuring the erythrocyte sedimentation rate (ESR)
- your plasma viscosity (PV) (the thickness of your blood) – this is an important test if you have Waldenström’s macroglobulinaemia
- serum protein electrophoresis to measure abnormal proteins in your blood if you have Waldenström’s macroglobulinaemia
- your blood group (if you need a blood transfusion)
- if you have signs of an infection, which can be measured by the CRP level or blood culture (growing any bacteria in your blood)
- if you have or have had a viral infection that could be related to the lymphoma or that could flare up while your immune system is low (viruses such as HIV, hepatitis B virus, hepatitis C virus, cytomegalovirus, or Epstein-Barr virus).
Your medical team might suggest other blood tests depending on your individual circumstances.
Most people dislike having blood tests, especially when frequent samples are needed or if it is difficult to get blood from your veins. Most people get used to the procedure if they need lots of blood tests but it can still be hard.
If you have always had a problem with blood tests, tell your medical team. There are ways of helping you to cope:
- if you tend to feel faint when you have blood tests, try lying down in a cool room when you have blood taken
- if the pain when the needle goes in bothers you, ask for some anaesthetic cream to numb the skin before the test
- look away during the procedure until it is completely finished
- listen to relaxing music during the procedure
- try taking someone with you to talk to you and take your mind off the procedure while the sample is being taken
- your medical team might be able to suggest a medicine to help you relax.
- If you have a needle phobia (severe anxiety about needles), your medical team might be able to refer you to a psychologist.