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Monocyte Count (Peripheral Blood)

Published: August 9, 2026Updated: August 16, 2026

This test measures the number of monocytes, a type of white blood cell, in your blood. Monocytes help fight infections and regulate immune responses.

Quick summary

["Monocytes are key immune cells that protect your body from illness and inflammation."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
33389-8
Short code
Monocytes NFr Pcar
Synonyms
Monocytes NFr Pcar
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is a Monocyte Count Test Used For?

Doctors may order a monocyte count test to evaluate immune function, detect infections, or assess conditions like chronic inflammation, certain cancers, or autoimmune diseases. It can also help monitor treatment responses in patients with blood disorders or immune-related illnesses.

When Might You Need This Test?

You might need this test if you have symptoms like frequent infections, unexplained fevers, fatigue, or swelling, or if your doctor suspects an underlying condition affecting your immune system. It’s also part of routine blood work in some cases, such as before chemotherapy or organ transplantation.

How Is the Test Performed?

A small blood sample is drawn from a vein, usually in your arm. The sample is then analyzed in a lab to count the number of monocytes. This is a quick and painless procedure that typically takes a few minutes.

What Do Results Mean?

Results show the number of monocytes in your blood, expressed as a count per microliter (µL). While reference ranges vary by lab, elevated or low monocyte counts may signal potential health concerns that your doctor will discuss with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Monocyte Count

Frequently asked questions

Why might my doctor want to know my monocyte count?
Your doctor may check monocyte levels to diagnose or monitor conditions like leukemia, lymphoma, or chronic infections (e.g., tuberculosis). It can also help identify immune deficiencies or inflammation-related diseases, such as rheumatoid arthritis or inflammatory bowel disease.
What are the normal ranges for monocytes?
There’s no single universal range—reference intervals depend on the lab. Typically, healthy adults have between 0.1% and 1% of white blood cells as monocytes, but these can shift with health or medical conditions.
Can lifestyle or diet affect monocyte counts?
Yes, stress, poor sleep, or certain diets (like high-sugar or processed foods) may temporarily influence immune cell counts, including monocytes. Avoiding extreme stress and maintaining a balanced diet can support overall immune health.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy