Home › Biomarkers › White blood cells
White blood cells, also called leukocytes, are part of your immune system, and the test measures how many of them are in your blood. A high value can point to inflammation, to your body reacting to bacteria or viruses or to an allergic reaction; a low value can point to damage to the bone marrow or to a condition of your immune system.[1]
On this page you can read what white blood cells are, what the guidelines say about a value that is too low or too high, what influences your value and which values are best to put beside it.
Also known as: leukocytes, leukocyte count, WBC. At the lab: KBB.
White blood cells, also called leukocytes, are part of your immune system. They are blood cells that are made in your bone marrow and that you find in your blood and in your lymph tissue, a part of your immune system. When you get ill, they travel through your blood and your tissue to the place where they are needed. There they help your body defend itself against bacteria, viruses and other substances that do not belong there.[1]
There are five main types of white blood cell: neutrophils, lymphocytes, monocytes, eosinophils and basophils. The white blood cell test adds all of these cells together. Another test, the blood count with differential, shows how many there are of each type.[1]
The test shows whether your white blood cell count is too high or too low, but on its own it cannot establish the cause. That is why the test is usually done together with other tests, such as a complete blood count, a blood count with differential, a blood smear or an examination of the bone marrow.[1]
When you get ill, your body makes more white blood cells to defend itself against the bacteria, viruses or other substances that are making you ill. That is why your value goes up. With other conditions your body makes fewer white blood cells than you need, and your value goes down.[1]
The test is mainly used to find or to follow conditions with a high or a low white blood cell count. Your doctor can request the test when there are signs of inflammation, with a condition in which the immune system attacks the body's own tissue, or with symptoms such as fever, chills, muscle pain, headache, a cough that does not go away, or a wound that is red, gives off pus or will not close.[1]
You may also need the test if you have a condition that makes your immune system weaker, or if you take a medicine that holds your immune response back. If the test shows that your white blood cell count is dropping too low, your doctor can adjust your care. The test is sometimes done in newborns and older children too, as part of a routine check or with symptoms that can belong to the white blood cells.[1]
If you already receive care for a condition of the white blood cells, your result can show how your value develops during that care. If you have questions about your result, discuss them with your doctor, who weighs your symptoms, your medical history and your other blood values as well.[1]
The laboratory BioProfile works with, Labplusarts, uses a reference value of 4.3 to 10.0 10^9/l for white blood cells (KBB). A value between those limits is one the lab calls normal.[2]
| Your value | What it can point to | Who it is for |
|---|---|---|
| Higher than normal (leukocytosis)[1] | Can point to inflammation, to your body reacting to bacteria or viruses, to an allergic reaction, to tissue damage after a burn or an operation, or to a condition of the blood or the lymphatic system | People whose test shows a high white blood cell count |
| Lower than normal (leukopenia)[1] | Can point to damage to the bone marrow, to a condition in which the immune system attacks the body's own tissue, to a condition of the immune system, or to a condition of the liver or the spleen | People whose test shows a low white blood cell count |
| High or low, without further investigation[1] | The test shows that the count is too high or too low, but on its own it cannot establish the cause, so other tests usually follow | Everyone who takes the test |
MedlinePlus (U.S. National Library of Medicine), White Blood Count (WBC): which kinds of conditions go with a high or a low white blood cell count. This source gives no threshold values of its own.[1]
A white blood cell count that is lower than normal is called leukopenia. It can point to damage to the bone marrow, for example from a condition or from certain medicines, to a condition in which the immune system attacks the body's own tissue, to a condition of the immune system itself, or to a condition of the liver or the spleen. The test cannot establish the cause on its own: your doctor looks at your symptoms, your medical history and your other blood values.[1]
A white blood cell count that is higher than normal is called leukocytosis. It can point to inflammation, to your body reacting to bacteria or viruses, to an allergic reaction, to tissue damage after a burn or an operation, or to a condition of the blood or the lymphatic system. Smoking, stress, a reaction to a medicine or being pregnant can also make your body produce more white blood cells.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
When you get ill, your body makes more white blood cells to defend itself against bacteria, viruses or other substances that do not belong there. That is why your value goes up. Inflammation and a condition in which the immune system attacks the body's own tissue also go with a higher value. Other conditions make your body produce fewer white blood cells instead.[1]
Certain medicines can lower your white blood cell count, and a reaction to a medicine can raise your value instead. You do not need to do anything special for this test, but do tell your doctor what you are taking: sometimes a medicine has to be left out for a while. Never stop a medicine on your own, only if your doctor says so.[1]
Smoking, stress and being pregnant can make your body produce more white blood cells, which makes your value come out higher. That is why it helps to know what your day looked like when your blood was taken.[1]
Tissue damage, for example after a burn or an operation, goes with a higher white blood cell count. Damage to your bone marrow moves your value too, but downwards.[1]
White blood cells is in all five packages, from BioProfile 31 up to BioProfile 150.[3]
The BioProfile editorial team wrote this page on 30 September 2026 from the sources below, which we read on 30 September 2026. Every number on this page appears in one of those sources, with the number of that source next to it. An expert still has to review this page; after that review, the name of that expert and the date of the review appear at the top. This page gives an explanation, not a diagnosis. Discuss an abnormal value with your GP.
