Blood and lab tests
What Are Monocytes on a Blood Test?
Monocytes · say it: MON-oh-sitesAlso written: MONO, monocyte count, absolute monocytes
Short answer
Monocytes are white blood cells that clean up germs and damaged cells. A blood count reports how many you have.
What it means
Monocytes are the largest white blood cells in the blood. They travel in the bloodstream for a short time and then move into tissues, where they turn into cells called macrophages. Macrophages swallow germs, dead cells and debris, and they send signals that call in other parts of the immune system.
Monocytes appear in the differential part of a complete blood count (CBC), which splits the total white cell count into its types. The report usually gives an absolute number and a percentage. The lab is showing how many monocytes are present, and a high or low flag means the result sits outside the range that lab uses.
On a printout, "MONO" or "MONO%" means monocytes. It does not refer to mononucleosis, the viral illness people often call "mono", even though both names come from the same word root.
Where you may see it
- The differential section of a CBC, shown as "MONO" or "MONO%"
- Patient portal blood results listing "Absolute monocytes"
- Hematology clinic letters that follow white cell counts over time
📄 How it looks on a report
Monocytes, absolute 0.9 x10^9/L H
🙅 What it does not mean
- MONO on a blood count is not a test for mononucleosis (glandular fever). That illness is checked with different blood tests.
- A slightly high monocyte count does not point to one particular disease. It can rise during recovery from an infection, with long-lasting inflammation and for many other reasons.
- The percentage alone can mislead. If the total white count is low, the monocyte percentage can look high even when the actual number of cells is ordinary, which is why labs also give an absolute count.
🗒️ Questions to ask your doctor
🧾 Reports where you will see “Monocytes”
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🔗 Read more from trusted sources
- “Monocytes” on MedlinePlus ↗
US National Library of Medicine
- MedlinePlus lab test guides ↗
US National Library of Medicine
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General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.