Blood count and blood group · Blood

Monocytes

A type of white blood cell that clears bacteria and dead tissue; part of the extended blood count.

At a glance

Measured in blood
In 5 test panels
No special preparation

Explanation

Monocytes: what is measured?

Monocytes are the largest white blood cells. They are made in the bone marrow, circulate briefly in the blood and develop in the tissues into macrophages (scavenger cells) that take up bacteria, dead cells and other harmful substances. The laboratory counts them as part of the white blood cell differential (the breakdown of the white blood cells into types).

What can it detect?

Long-lasting (chronic) infections and inflammation, for example tuberculosis or an inflammatory bowel disease
The recovery phase after an acute infection
Rarely: a blood disease, such as chronic myelomonocytic leukemia

Result

What does the result mean?

Monocytes too high

A raised monocyte count (monocytosis) usually fits an infection that has been going on for some time or recovery after an infection. Chronic inflammatory diseases, such as rheumatoid arthritis or an inflammatory bowel disease, can also raise the count. A slightly raised value in someone without symptoms is usually temporary. A strongly or persistently raised count is rare and can go with a blood disease, especially if other blood cells are also abnormal; symptoms that go with this are tiredness, fever, night sweats or weight loss.

Monocytes too low

A low monocyte count (monocytopenia) is uncommon and, with an otherwise normal blood count, usually has no meaning. Corticosteroids (anti-inflammatory drugs such as prednisone) and chemotherapy lower the count temporarily. Rarely: a bone marrow disorder or a rare form of leukemia (hairy cell leukemia) with a persistently low count; the other white blood cells are then usually low as well.

After an abnormal result

With a slightly raised or low count without other abnormalities, the GP usually repeats the blood count after a few weeks. With a persistently or strongly abnormal count, especially if other blood cells are also abnormal, testing for an infection or inflammation follows and, if needed, referral to the internist (specialist in internal medicine) or hematologist (specialist in blood diseases).

Reliability

How reliable is the test?

The monocyte count is part of the blood count and is rarely decisive on its own. According to the Dutch Society for Clinical Chemistry (NVKC), an abnormality points to involvement of the immune system, but not to a specific disease; the value is always assessed together with the total number of white blood cells, the other cell types and the symptoms. An isolated slightly raised value is often temporary and is preferably repeated.

What can affect the result?

A recent infection, even a common cold, can raise the count for a few weeks.
Corticosteroids and chemotherapy lower the count; some medicines raise it instead.
Laboratories differ in reference values and in reporting as a percentage or as an absolute count; the absolute count is the most reliable.
With a small number of cells, the count is less accurate.

Who it is for

Who is the test useful for?

Useful for

Useful as part of an extended blood count with symptoms that fit a long-lasting infection or inflammation, such as persistent fever, night sweats, weight loss or prolonged tiredness, and for monitoring a known blood disease. As a single test, it has little value, and routine measurement is not needed in adults without symptoms.

How common is it?

There are no Dutch figures on how often an abnormal monocyte count is found. A slightly raised count is common, because infections and inflammation are common. Blood diseases in which monocytes are strongly raised, such as chronic myelomonocytic leukemia, are rare and occur mainly at an older age.

NVKC, allesovertesten.nl

Drawbacks and risks

A slightly abnormal monocyte count is usually harmless; as an isolated finding, it can lead to unnecessary worry.

Get tested

Monocytes: test panels

Monocytes is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.

Blood draw
Complete Blood Count (CBC)
Complete Blood Count Extended; standard blood count plus detailed white blood cell analysis.
€ 27,00
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Complete hormonal analysis with testosterone, DHEA-S, thyroid, blood count, liver function, kidney function, lipids, glucose, HbA1c, insulin, hs-CRP, vitamin D and ferritin.
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Whoop (Advanced Labs)
Comprehensive blood analysis with biomarkers that integrates directly with your WHOOP wearable for optimal performance and recovery.
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Fingerstick
Full blood count with differential (CBC) (finger-prick)
Full blood count including haemoglobin, platelets and a white cell differential.
€ 27,00

How reliable is the test?

Monocytes