Understanding blood tests a guide for people with lymphoma

Transcription

1 Freephone helpline Understanding blood tests a guide for people with lymphoma When you are being tested or treated for lymphoma you will have to have blood samples taken from time to time. You might wonder what the blood tests are all for and what the results mean. This article aims to answer the most common questions people ask about blood tests: Why are blood tests done when you have lymphoma? What do blood tests measure? Where do blood cells come from? How does lymphoma affect the different blood cells the white blood cells, platelets and red blood cells? How long does it take for the blood cells to recover from the treatments? Why do I need blood tests done before chemotherapy cycles? What can I do if I find having blood tests frightening? There are some other, more specific questions about blood tests that callers to our helpline ask from time to time and we have answered these too. Lastly, there will be some information on the most common blood tests and what they mean and suggestions on where you can get more information on blood tests. Why are blood tests done when you have lymphoma? are done for various reasons, for example to: help suggest the diagnosis when lymphoma is first suspected (this blood test evidence will then lead the medical team to order other, more specific tests like a biopsy) assess the lymphoma before treatment starts check your general health before or during treatment assess your progress or detect the development of complications during treatment check whether you have recovered adequately from one cycle of treatment before starting the next one monitor the lymphoma during periods when you have not yet started treatment or after the treatment is finished. 1/10

2 Of course you might need to have other samples taken to assess you fully, such as urine, bone marrow or tissue biopsy samples. You might also have other tests arranged (such as scans) at the same time as the blood tests. What do blood tests measure? When you have blood taken this could be for just one test or for a huge number of individual tests in different laboratories. The amount of blood taken and the number of different coloured bottles might give you a clue about this. It is important to remember, though, that however much blood seems to have been taken, it will only be a tiny fraction of the total amount of blood you have in your body and it will be replaced by the body in a short time. The sorts of things that can be tested for are: the numbers of blood cells the blood counts and what the blood cells look like under the microscope levels of chemicals in the blood, for example to check how well the liver and kidneys are working the levels of hormones in the blood, for example thyroid hormones or hormones from the ovaries your blood group doctors need to know this if you ever have to have a blood transfusion the presence of any infectious organisms like bacteria in the blood (this would be checked if you are generally feverish and unwell) how well your blood clotting system is working whether the level of certain drug treatments is right. Where do blood cells come from? Blood cells come from the bone marrow a spongy area inside the long bones (eg the thigh bone) and the flat bones (eg the hip bone). When we are babies, blood cells are made in nearly all our bones but as we grow a lot of the marrow in the more distant bones becomes fatty. Blood production continues mostly in the more central bones, such as the thighs, breastbone and back. The bone marrow provides a home that protects the immature blood cells the stem cells as they develop into mature functioning cells. When they are fully mature they are released into the bloodstream to carry out their jobs. How does lymphoma affect the blood cells? In order to answer this question we will look at what the different blood cells do and how they are affected by lymphoma. First we will explain briefly what a full blood count is and why lymphoma treatments affect this. Then we will give some separate information on each of the three main types of blood cells that you are likely to hear about. 2/10

3 The full blood count A full blood count (FBC for short) is done to look at the numbers of the different types of blood cells in your blood. The machine in the laboratory also gives an indication of the average sizes of the cells and other useful information about them. In some cases a blood smear is prepared from the sample and is specially stained to look at the cells directly under the microscope. This test gives the doctors more detailed information on the blood cells, for example on whether they look normal in size and shape. Blood smear under the microscope showing red and white blood cells (Science Photo Library / C012/4499) The numbers of blood cells (the counts ) and their appearance can help in the diagnosis of some lymphomas. There is some more information on the FBC in the table on page 9. Why do lymphoma treatments affect the blood counts? Treatments such as chemotherapy and radiotherapy are used to kill off lymphoma cells but unfortunately these treatments don t distinguish between normal cells and abnormal cells. This means that the numbers of your normal bone marrow cells are often reduced by the treatments. In addition, your bone marrow might not be working very well if there is lymphoma in the marrow itself. This reduction in bone marrow cells means that fewer normal blood cells are manufactured. Fortunately, normal cells recover from the effects of the drugs faster than cancer cells, so the blood cells usually recover quite quickly and the counts go up again. What are the main types of blood cell that are assessed in the FBC? The main types of blood cells measured in the FBC are red blood cells, white blood cells and platelets. Red blood cells are the most numerous of the different blood cells but we are going to describe the white blood cells first. This is because they are the cells that are most affected by lymphoma and by lymphoma treatments. 3/10

4 White blood cells and lymphoma What do white blood cells do? There are several types of white blood cell, all of which are involved in different ways in defending the body against infection and in clearing up after infections. White blood cells are also involved in our general immunity to infections, in inflammation and in allergic reactions. The numbers of white blood cells and their appearance in the FBC and in a blood smear can occasionally help to detect a lymphoma and suggest what kind of lymphoma it is. Are white blood cells affected by lymphoma treatment? Yes, the white blood cell counts often fall. For people who are being treated for lymphoma the important white blood cells are the neutrophils. These only last in the bloodstream for a few days and they normally ingest (eat) and destroy bugs. This means that you can have problems with infections if the bone marrow can t produce them and you have fewer of them for a while. What does having a low neutrophil count mean to me? Having a low neutrophil count is called neutropenia. Getting an infection in this situation can be very serious. Because you don t have your normal defences, bugs that are normally harmless can overwhelm you. You might need intravenous antibiotics and other support to get over this, often in hospital. If you are unwell with a fever during your chemotherapy cycles you must therefore seek advice quickly. If you are also on steroids these can mask the fever, so if you feel distinctly unwell, even with a normal temperature, you should contact your medical team straightaway. You should have been given telephone numbers from your treatment centre to call at any time of the day or night in these circumstances it is important to use them. Platelets and lymphoma What do platelets do? Platelets are small cell fragments that help your blood to clot. They plug any cuts or defects in the blood vessels while the chemical clotting factors in your blood get to work to stabilise the plug. This plug then scars over and heals. The number of platelets measured in the FBC can sometimes be low in certain types of lymphoma that are present in the bone marrow. A low level of platelets is called thrombocytopenia. Are platelets affected by lymphoma treatment? The production of platelets is affected by lymphoma treatments in just the same way as white blood cells are affected. Platelets last for longer in the bloodstream so platelet levels don t tend to drop so far. It is therefore not so common to need treatment for low platelet counts when you are on lymphoma treatment, but this will depend on whether there is lymphoma in the bone marrow and on how intense the treatment is. How would I know if I have low platelets? A low platelet count won t affect how you feel in yourself but can mean that you bruise or bleed easily, to a much greater extent than you would normally expect from minor injuries, 4/10

5 for example. You might notice tiny areas of bleeding in the skin as little red spots on your lower legs this is known as purpura. If you are bruising or bleeding from a lack of platelet production, then a platelet transfusion (a bag of platelets from a donor) can be given to tide you over. Rarely, low levels of platelets can happen for other reasons and alternative treatments might be needed, rather than platelet transfusions (eg steroids). Red blood cells and lymphoma What do red blood cells do? Red blood cells are much more numerous in the blood than the other cells, which is why blood is deep red in colour. The red cells contain a protein called haemoglobin, and oxygen that has been breathed into the lungs attaches itself to this protein as the blood passes through the lungs. The job of red blood cells is therefore to carry oxygen around the body. If your red blood cell count is low or if the amount of haemoglobin in the red blood cells is low, this is called anaemia, which can make you feel tired and breathless. Some people with lymphoma will be anaemic when the lymphoma is first diagnosed. Are red blood cells affected by lymphoma treatment? Yes, but they are fairly long-lived cells (they last for months rather than days), so you can often keep your oxygen-carrying capacity up reasonably well during chemotherapy. However, if you are anaemic to start with, have lymphoma in your bone marrow or have treatment complications, a blood transfusion is sometimes necessary. If your chemotherapy is prolonged, the production of red blood cells in the bone marrow might be halted for so long that transfusion becomes inevitable. How long does it take for blood cells to recover from the treatments? This varies between different chemotherapy regimens and between individuals. With the standard outpatient chemotherapy regimens used for most lymphomas, the lowest point in the cell counts (you might hear this referred to as the nadir ) usually comes 7 14 days after the first day of the chemotherapy treatment cycle. After this low point the cell counts begin to rise. Because there is variation between people in how quickly this happens, however, your blood counts will be checked before each cycle of treatment. Why do I need blood tests before chemotherapy cycles? Generally, blood tests are done at this stage to check that the blood cells have recovered from the last chemotherapy cycle, but they are also done to check that your liver and kidneys have not been damaged. Occasionally the tests will be done to check that you don t need a transfusion or to check that an infection has cleared up. Chemotherapy treatments are designed to be given at intervals, in cycles. The time between chemotherapy cycles is determined by the length of time it takes most people to recover 5/10

6 just enough from the previous cycle to cope with another one. This means that the tests need to be done as close to the start of the next cycle as practically possible. On the other hand, complex technology and expert interpretation is involved in doing these blood tests, so a certain amount of time is required to get the results back. It is a fine balancing act to time the tests correctly. Sometimes a delay in starting the next cycle is needed to allow further recovery of your blood counts, or you might need some treatment to boost the counts. Most treatment protocols and all clinical trials include detailed instructions on what happens if the (Science Photo Library M530/0669) blood cell numbers are insufficient before treatment. Very occasionally, treatment protocols proceed metronomically, meaning that the next cycle of treatment starts on time, whatever the blood tests show. What can I do if I find having blood tests frightening? You are not alone. Nobody is keen on having blood tests, especially when frequent samples are needed or if it is difficult to get blood from your veins. If you have to have a lot of tests done you tend to get more and more used to the process but it can still be hard. Some people have found that it helps to have someone with them, such as a family member or a friend, to chat to while the sample is being taken. There is a lot that can be done to ease the situation if you have always had a problem with blood tests. Firstly, it is important to explain how you feel to the nurses and phlebotomists (people specially trained to take blood). There are generally two distinct types of problem, though some people suffer from both. Firstly, if you tend to come over peculiar or feel faint, then you should be lying down in a reasonably cool room to have blood taken. If the needlesting is part of the problem, ask for some anaesthetic cream to put on beforehand (such as EMLA cream). Another important thing to do is to look away during the procedure until it is completely finished. The second type of problem is a much more deep-seated needle phobia, which is a recognised medical condition in which people experience intense anxiety before blood is taken or before other procedures involving needles. This often goes back to having a bad experience as a child. The tips described in the last paragraph often help but it is well worth also considering taking a sedative tablet beforehand and listening to some relaxation music during the procedure. If there is enough time you could be referred to a psychologist for help. In the interests of time, this kind of help would usually take the form of a fast phobia cure rather than a more prolonged psychoanalytical process. 6/10

7 You should also ask your nurse to anticipate how much trouble taking repeated blood samples will be for you and for them. This will depend on the particular treatments you will be given and on how easy or difficult they think it will be to take blood from your veins. If they think that taking repeated blood tests from you could be difficult, ask about having a central line inserted (such as a Hickman line). As well as being used for giving you chemotherapy and other treatments directly into your veins, it might be possible to take blood tests through the line. Other common questions people ask about blood tests How can my blood tests be normal if I have lymphoma? To affect the blood tests the lymphoma has to exert some influence on the bone marrow or the organs or have particular features which show up in some tests. If the lymphoma is just confined to the lymph nodes (glands) it might not affect any of the blood tests. Another reason for normal tests is that you are in remission. Why do some people have more tests than others? If someone appears to be having more tests than you this could be because: the treatment for their lymphoma needs to be more intense than yours they have had some complications previously they have lymphoma in the bone marrow they have other medical conditions that need extra monitoring, such as diabetes. How do the doctors and nurses decide which tests to do? Which tests are needed and when they are needed is determined by: any symptoms you are having that the doctors want to investigate the type of lymphoma you have the type and intensity of the treatment you are having the blood cell counts you need to achieve before proceeding to the next cycle the treatment protocol or clinical trial you are on the complications that can be associated with the particular drugs you are taking your previous blood results. Can I see my results? You can, of course, ask to see these. Your nurses will often discuss the results in detail with you. Please ask your doctor or nurse if you are worried about a particular result it might not mean what you think it does and you can worry needlessly about results that are not concerning to the medical team. Can tests be taken through my central line? Generally yes, blood samples can be take through a Hickman line or PICC (peripherally inserted central catheter). However, even a line working very well can fail to give out samples despite the doctors or nurses best efforts usually due to the position of the line at the other end. 7/10

8 Why do tests sometimes have to be repeated? It is quite common for blood tests to be repeated. Here (in no particular order) are the commonest reasons why this might happen: It is rare for there to be a problem with the sample or bottle itself or for a technical hitch in the laboratory but it can happen, and then the test would need to be repeated. Occasionally a test result is unexpectedly very abnormal so the laboratory will suggest repeating it soon if the abnormality is confirmed, action can be taken to correct it if needed. Samples for cross-matching blood for transfusion sometimes need to be repeated nearer to the time of the transfusion to confirm the blood type shown in the previous test. The rules about this tend to get stricter the more transfusions you have, as you are more likely to have developed an antibody and so risk having an immune reaction against the next transfusion. If your pre-chemotherapy tests are close to the desired levels (but not quite good enough) and the laboratory feels that they are likely to be satisfactory by the day of your next cycle, they might ask for the tests to be repeated just before you proceed with the next treatment. Tests for detecting infection or your body s response to infection might need to be repeated to see if it has cleared up. I have far fewer tests now I m being followed up why? It is only when you are having treatment that you will experience the more sudden and/or short-lived changes in your blood tests, such as the blood cell counts dropping. In addition, the complications of treatments are much more likely to happen while you are still on the drugs. This is why you are closely monitored by blood tests while you are on treatment but don t need so many afterwards. If particular blood tests, such as the lactate dehydrogenase (LDH) or the erythrocyte sedimentation rate or ESR (see the table on page 9), were found to be raised because of your lymphoma, then repeating these tests can be helpful when you are being followed up. How often they should be done is open to debate most tests generally tend to be less useful later on during the follow-up stage than they are while you are actually having symptoms of the illness. Why do you need blood tests if you take warfarin? A few people develop a clot in the veins (for example in the lung) during their lymphoma treatment and this is usually treated with injections of an anticoagulant (anti-clotting) drug called heparin. If you need treatment with heparin you might be switched later to warfarin tablets to thin the blood. You will be given quite a bit of information about this treatment. Because different people respond to these tablets differently, each person will need a slightly different dose of warfarin to achieve the same degree of blood thinning. The laboratory staff and doctors judge the correct dose of warfarin to give you by doing regular blood tests (the main one is called the INR, which is short for international normalised ratio ). If there are changes in your health (for example if you are put on antibiotics) the warfarin dose will often need to be changed. This means that you will need extra monitoring tests done in order to adjust the dose accurately. Unfortunately, there is no substitute for having regular tests until you come off warfarin. 8/10

9 Some common tests explained FBC ESR A full blood count is a test that measures the numbers of red blood cells, white blood cells and platelets in your blood. There is not an exact number of cells that is regarded as being normal there is a range of numbers that is regarded as normal and this range varies slightly between laboratories. The range also differs between men and women and in children. This stands for erythrocyte sedimentation rate and it is a test that measures the thickness of the blood. Some laboratories do a similar test called the plasma viscosity. Both tests measure the same thing and give the same information. The ESR is commonly raised if lymphoma is present. Because the ESR can be raised if lymphoma becomes active, keeping an eye on your ESR is one way of checking that the lymphoma has not relapsed (come back). A word of warning: the ESR is not useful for assessing lymphoma activity in everyone with a lymphoma, and it can be raised or abnormal in many other medical conditions (eg in infections) so it needs to be interpreted carefully. CRP LDH This stands for C-reactive protein and this is another general test. It is not generally used for monitoring the lymphoma itself but can be very useful to monitor you if you have a serious infection (it is high to start with and drops if the antibiotics are working). This stands for lactate dehydrogenase, which is a substance in the blood which is at higher than normal levels in some types of lymphoma. Raised LDH levels in the bloodstream might indicate that a lymphoma is growing, but (as with the ESR) a high LDH level can be present as a result of other medical conditions as well. Acknowledgement The Lymphoma Association is grateful to Dr Paul Revell, consultant haematologist at Stafford Hospital, for writing this article in 2009 and for updating this new version. Useful sources of further information on blood tests NHS Choices CancerHelp UK (Cancer Research UK) (Monday Friday, 9am 5pm) via website 9/10

10 References Hoffbrand AV, Moss PAH. Essential Haematology. 6th edition Wiley-Blackwell, Oxford. Deacon B, Abramowitz J. Fear of needles and vasovagal reactions among phlebotomy patients. Journal of Anxiety Disorders, : Fernandes PP. Rapid desensitization for needle phobia. Psychosomatics, : Hamilton JG. Needle phobia: a neglected diagnosis. The Journal of Family Practice, : How we can help you We provide: a free helpline providing information and emotional support (9am 6pm Mondays Thursdays; 9am 5pm Fridays) or information@lymphomas.org.uk free information sheets and booklets about lymphoma a website with forums and a chatroom the opportunity to be put in touch with others affected by lymphoma through our buddy scheme a nationwide network of lymphoma support groups. How you can help us We continually strive to improve our information resources for people affected by lymphoma and we would be interested in any feedback you might have on this article. Please visit or publications@lymphomas.org.uk if you have any comments. Alternatively please phone our helpline on We make every effort to ensure that the information we provide is accurate but it should not be relied upon to reflect the current state of medical research, which is constantly changing. If you are concerned about your health, you should consult your doctor. The Lymphoma Association cannot accept liability for any loss or damage resulting from any inaccuracy in this information or third party information such as information on websites which we link to. Please see our website ( for more information about how we produce our information. Lymphoma Association PO Box 386, Aylesbury, Bucks, HP20 2GA Registered charity no Produced Next revision due /10