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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 inflammation.

Quick summary

["Monocytes help your immune system respond to infections and tissue damage."]

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

Key facts at a glance

LOINC
68422-5
Short code
Monocytes # Plr Manual
Synonyms
Monocytes # Plr Manual
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What Is a Monocyte Count Used For?

Doctors may order a monocyte count to diagnose or monitor conditions affecting your immune system, such as infections, inflammatory diseases, or certain blood disorders. It can also help evaluate responses to treatments or identify risks for conditions like leukemia or autoimmune diseases.

How Is This Test Done?

A small amount of blood is drawn from a vein in your arm. The blood is then examined under a microscope to count the monocytes. This test is typically done as part of a routine blood test.

When Might You Need This Test?

You might need a monocyte count if you have symptoms like fever, fatigue, unexplained weight loss, or persistent infections. Doctors may also order it before surgery, to check for infections, or to monitor chronic conditions like rheumatoid arthritis or lupus.

What Are Common Reasons for Abnormal Results?

Elevated monocyte counts may suggest chronic infections, inflammatory diseases, or certain cancers. Low monocyte counts could indicate immune deficiencies, bone marrow disorders, or severe infections. However, results alone don’t diagnose a condition—your doctor will consider your full medical picture.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

How Does This Test Fit Into Your Health?

Short name

Monocyte Level

Frequently asked questions

Why might my doctor want to check my monocyte level before or after starting a new medication?
Monocyte levels can help doctors assess how your body is responding to treatments, especially for conditions like cancer or autoimmune diseases. For example, if you’re on chemotherapy, low monocytes might mean your immune system is weakened. If you’re on anti-inflammatory drugs, high monocytes could indicate the treatment isn’t working as expected.
Could my diet or lifestyle affect my monocyte count?
While diet and lifestyle factors like stress or sleep can influence overall immune health, they don’t directly change monocyte counts. However, chronic stress or poor sleep may indirectly affect inflammation, which could be linked to monocyte levels. Always discuss lifestyle changes with your doctor.
What should I do if my test results are different from last time?
If your monocyte count changes significantly, your doctor will review the results with you and may order additional tests or ask about recent illnesses, treatments, or symptoms. Never interpret results alone—always talk to your healthcare provider.
  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