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Monocytes are white blood cells that kill bacteria, viruses and other germs. A high white blood cell count can point to inflammation, and a low count can point to a bone marrow disease.[1]
On this page you can read what monocytes are, what the guidelines say about a value that is too low or too high, what affects your value and which other values are best to look at alongside it.
Also known as: monocyte count, part of the white blood cell differential (differential white blood cell count). At the lab: GBBX.
Monocytes are white blood cells. White blood cells are made in your bone marrow. They are found in your blood and in your lymph tissue. They are an important part of your immune system.[1]
There are five types of white blood cells, and monocytes are one of them. They kill bacteria, viruses and other germs that can make you ill. They also strengthen your body's defences and clear away dead cells.[1]
Your monocytes are measured in a blood test that counts each type of white blood cell separately. That test measures the amount and the percentage of each type. Another test counts your total white blood cells.[1]
Each type of white blood cell does a different job. That is why measuring them separately gives your healthcare provider important information about your health.[1]
The test is often part of a routine check-up. A healthcare provider can also order it to look for the cause of symptoms, such as feeling unusually tired or weak, or bruising for no clear reason.[1]
The test also helps to monitor an existing blood condition. To understand your result, your healthcare provider also looks at your symptoms, your medical history and other blood tests.[1]
Labplusarts, the lab BioProfile works with, measures monocytes as a number per litre of blood, in 10^9/l. A widely used handbook for doctors gives 0.2 to 0.95 10^9/l as the usual range for adults. Your own result shows the range the lab uses for your measurement.[2]
| Value | What it means | Who it is for |
|---|---|---|
| 0.2 to 0.95 10^9/l[2] | Usual range | Adults |
Source: Harrison's Principles of Internal Medicine, normal white blood cell values in adults.[2]
MedlinePlus does not give separate causes for monocytes. For white blood cells as a whole, the source says a low count can point to a bone marrow disease. Certain medicines, such as antibiotics, can also lower the count.[1]
Here too, the source is about white blood cells as a whole. A high count can point to inflammation, an immune system disorder, an allergic reaction or a disorder of the blood or the lymph nodes. Certain steroids can also raise the count. If your result is abnormal, your healthcare provider may order extra tests.[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.
Certain medicines, such as antibiotics, can go together with a low white blood cell count. Certain steroids can go together with a high count.[1]
Smoking and drinking alcohol can affect your result. So a value outside the normal range does not always mean you have a condition that needs medical care.[1]
Extreme stress or a physical injury can also affect your result.[1]
When you are ill, your white blood cells travel through your blood to where they are needed. That is how inflammation or an allergic reaction can go together with a higher count.[1]
Monocytes are included in all five packages, from BioProfile 31 to BioProfile 150.[3]
The BioProfile editorial team wrote this page on 2 October 2026 from the sources below, which we read on 2 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; once checked, the expert's name and the date of the check will appear at the top. This page offers explanation, not a diagnosis. Discuss an abnormal value with your GP.
