Blood tests are one of the most common types of medical test.
A blood test is a simple procedure. It involves taking a sample of blood to be tested in a laboratory.
- red blood cells, which carry oxygen around your body
- white blood cells, which help fight infections
- platelets, which help your blood clot if you are injured
- proteins, such as antibodies, enzymes and chemical messengers
- salts, such as sodium, calcium, potassium and chloride, which help keep your body fluids in balance
- sugars and fats.
The levels of each of these in your blood can give your medical team useful information about your health.
Blood tests have a wide range of uses. For example, a blood test can be used to:
- check your general health
- see if you have an infection
- see how well your organs, such as your liver and kidneys are working
- screen for some genetic conditions.
Most types of lymphoma can’t be diagnosed by a blood test alone. However, most people affected by lymphoma will have blood tests as part of their diagnosis and frequently throughout treatment. You continue to have blood tests, though less frequently, after treatment during follow-up.
Blood tests can help your medical team find out how the lymphoma is affecting your body, and to plan the best treatment for you.
You might also have blood tests to:
- see how your treatment is affecting you (including monitoring for side-effects)
- check whether you have recovered enough from one round of treatment before starting the next one
- monitor how your body is recovering after treatment
- check for late effects that might develop after lymphoma treatment
- look for any signs that might suggest your lymphoma has come back (relapsed) – although the person who has lymphoma usually notices this first and it is very rare for relapse to be picked up on a routine blood test.
Many different blood tests are used for people with lymphoma. The most common is the full blood count.
Full blood count
A full blood count (FBC) is a test that measures how many blood cells you have in your blood. The number of each type of blood cell is often called the ‘count’.
Lymphoma and many treatments for lymphoma can cause low blood counts, such as:
- anaemia – low levels of red blood cells or haemoglobin (the protein in your red blood cells that carries oxygen)
- thrombocytopenia – low levels of platelets
- neutropenia – low levels of a particular type of white blood cell called neutrophils.
A full blood count can also check for high levels of particular types of blood cell. For example, if you have an infection or chronic lymphocytic leukaemia (CLL), you might have a high white blood cell count.
Other blood tests
Although some of these tests use complicated laboratory techniques, they only need a small sample of blood. The process of having a blood test is the same.
You might have blood tests to find out more about your lymphoma. These could include:
- A blood film to see what your blood cells look like under a microscope. It is used to check for unhealthy (abnormal) cells.
- A test called immunophenotyping, immunohistochemistry or flow cytometry to find out what proteins your white blood cells are making. This can help your medical team diagnose the type of lymphoma you have.
- A plasma viscosity test is sometimes used to measure how thick your blood is. This is an important test if you have Waldenström’s macroglobulinaemia.
- A serum immunoglobulin test to measure your antibody levels. Antibodies usually help your body fight infection. In some types of lymphoma, certain antibody levels might be high. With some types of lymphoma, or after some lymphoma treatments, antibody levels might be low. This can increase your risk of getting infections. If your antibody levels are low and you have severe or recurrent infections, you might have immunoglobulin replacement therapy.
- Tests to check the levels of abnormal antibodies in your blood. This might involve a test called serum protein electrophoresis, which can test for an abnormal antibody called a paraprotein, or a test to measure levels of particular abnormal antibodies called cryoglobulins.
- Tests to measure the level of activity of certain proteins in your blood, such as lactate dehydrogenase (LDH) or Beta-2 microglobulin. Levels of these proteins can be high in people who have lymphoma. However, they can also be high for lots of other reasons, such as inflammation, infection or kidney problems. Having high levels of these proteins does not mean you definitely have lymphoma.
You might have other blood tests to find out more about your general health. These might check:
- How well your liver is working (liver function tests, or LFTs).
- How well your kidneys are working. This involves testing levels of salts (‘electrolytes’ – for example, potassium, calcium and chloride) and waste products in your blood using a test called urea and electrolytes or U&Es. You usually have levels of a waste product called creatinine measured at the same time.
- Whether you have any signs of inflammation in your body. This might involve measuring the levels of a protein called C-reactive protein (CRP) in your blood. CRP is a chemical that is released by damaged cells. Another test for inflammation involves measuring how quickly your red blood cells settle to the bottom of a test tube (your erythrocyte sedimentation rate or ESR). If there are inflammatory chemicals in your body, your red blood cells settle faster than usual.
- Whether you have, or have had, a viral infection. A viral infection could be related to your lymphoma or that could flare up during your treatment. This is called viral serology. It can be used to check for several viruses, such as HIV, hepatitis B or C virus, cytomegalovirus, or Epstein-Barr virus.
- How well your thyroid gland is working (thyroid function tests). Some treatments for lymphoma can cause an underactive thyroid.
- Your blood group (for example, if you need a blood transfusion).
Your medical team might suggest other blood tests depending on your individual circumstances. Lab Tests Online has a tests index with more detailed information on many different blood tests.
You might have blood tests at your local GP surgery or at a hospital outpatient department or clinic. Depending on where you’re having your tests, you might need to book an appointment in advance, or you might be able to walk-in at any time. You’ll be given all the information you need to book and prepare for your tests.
If you’re staying in hospital or you’re having treatment on a day care unit, you usually have your blood tests on your ward.
How should I prepare?
For most blood tests, you don’t need to do anything to prepare.
For some blood tests, you might need to fast (not eat or drink anything except water) or stop taking particular medications for a certain amount of time before your test. Your medical team should tell you if you need to do this.
How is the blood sample taken?
A doctor, nurse or phlebotomist (someone trained to take blood) takes the sample. The whole process only takes a few minutes.
- They clean the skin where they’re going to take the sample – usually from a large vein in the inside of your elbow. For young children, they might apply some cream or spray to numb the skin. This is not usually offered to adults but if you are very nervous, ask if it is available.
- They wrap a tight band around your upper arm to make the vein swell. This makes it easier to take the sample.
- They insert a needle into your vein. This might sting a little but only for a moment. Tell the doctor, nurse or phlebotomist if you are in pain.
- They collect your blood in tubes connected to the needle. Depending on what tests you need, they might collect several tubes but each tube only contains a small amount of blood.
- They remove the band from your arm and take out the needle.
- They apply a plaster or small dressing. You can take this off after a few hours.
If you have a central line or peripherally inserted central catheter (PICC) line, you might have your sample taken through your line.
Many people dislike having blood tests. You might be anxious about the needle, or be uncomfortable with the sight of your own blood.
If you’re worried about having blood tests, tell your medical team. They can suggest ways to help you cope. For example:
- If you feel faint or dizzy when you have blood tests, you can ask to lie down when you have blood taken.
- If you’re concerned about the pain when the needle goes in, you might be able to have some cream to numb your skin first.
- If you don’t like the thought or sight of blood, you can look away or distract yourself in some way until your blood test is over. You could take someone with you to chat to help take your mind off the blood test.
- If you feel anxious during the test, you could try some relaxation techniques, such as breathing techniques or distract yourself by listening to music.
The NHS have advice on needle phobia and overcoming your fear.
What happens afterwards?
Most people go straight home after having a blood test, unless they need to stay for more tests, treatment or a clinic appointment.
Occasionally, some people feel faint or dizzy. If this happens to you, tell the person taking the blood sample. You might have to lie down until you feel better.
You might have a small bruise where the sample was taken. It might ache a little for a day or so.
Depending on what tests are done on the blood sample, it can take anywhere from a few minutes to a few weeks to get the results of your blood tests. Your medical team can advise you when to expect your tests results.
Waiting for test results can be an anxious time, but it is important for your medical team to gather all the information they need in order to plan the best treatment for you.
Your medical team should tell you the results of your blood tests and explain what these results mean for you.
Blood test results usually list your own result along with a ‘reference range’ or ‘normal range’. This is the range of values that are seen in most healthy people. If your result is lower or higher than the reference range, it might indicate a particular health issue.
However, around 1 in 20 healthy people have results outside the reference range. If you have a blood test result that is not within the reference range, it does not necessarily mean you have a health issue. Your medical team look at your individual circumstances to decide whether or not your blood test result is a cause for concern. They can explain what the results mean in your particular case.
Ask your medical team if anything about your results concerns you.