Question: What is a full blood count?

Answer: Jeni Jones, Support Manager, Pancreatic Cancer UK

The full blood count is an important test for anyone on chemotherapy. The test looks at four important components in the blood -haemoglobin level, white cell count, neutrophil count and platelet level. All of these are produced in the bone marrow.

 Chemotherapy can cause bone marrow depression, and sometimes the blood count cannot "recover" or mature in time for the next cycle to go ahead.  This is not due to anything you have done or not done, and it will usually return to normal with a longer break. There is nothing you can do to make it recover any quicker.

The haemoglobin is important as it carries oxygen through the body. When the level drops, you can become anaemic, and can get tired, and possibly short of breath. You may also get headaches or dizziness, and feel generally lethargic. There are acceptable levels of haemoglobin for a cancer patient on chemotherapy, which are lower than what they are normally. So, even if your level is lower than it is supposed to be, it is very possible that you will still receive chemotherapy.

If the reading is below the required level, then you may need to have a blood transfusion. This is a fast and efficient way of correcting anaemia. You will have a special blood sample called a "cross match" taken. This allows the lab to match your blood type safely. Each chemotherapy unit will have a specific value below which they will not give chemotherapy, without having a blood transfusion first. The nurses at your unit will explain this to you. It is usually above 10g/dl (grams per decilitre).

White blood cells are the infection-fighting cells in the blood. They also defend the body against foreign materials. They are made up of many different types of white blood cells, and they can be divided into two groups -Granulocytes and Agranulocytes. Within each group there are different types of 'cytes', which all go to make up the White Blood Cell Count.

Neutrophils are a type of granulocyte. They defend the body against infection - bacterial and fungal. They are the "first on the scene" when the body gets an infection. Their lifespan lasts about 8 days. If the neutrophil count is low, you are at more risk of infection. For this reason, you should keep an eye on your temperature during chemotherapy, especially if you feel unwell. When you get a high temperature, it can signify that there is a problem with the neutrophil count. You will need to have your full blood count checked, and possibly be admitted to hospital. You will be given antibiotics, either orally or intravenously, so that these can act as an artificial "defence" barrier until your own neutrophil count improves.

Platelets are tiny components within the blood which help in the clotting process. Their lifespan is about 5-9 days. A low platelet count may result in bleeding - from the gums, nose, or a failure to stop bleeding even from a minor cut. You may also notice that you bruise more easily. If this happens, you should let the nursing staff know as soon as possible. Usually, it is enough to have an extra break from treatment and the count will recover naturally. It is unusual to need to have a platelet transfusion, but this may need to happen if the platelet count is very low.