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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 are part of your immune system and help protect your body from illness."]

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

Key facts at a glance

LOINC
71604-3
Short code
Monocytes NFr.DF Pcar Manual
Synonyms
Monocytes NFr.DF Pcar Manual
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
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

Why Is This Test Done?

Your doctor may order this test to check for infections, certain blood disorders, or immune system conditions. It can also help monitor treatments for conditions like leukemia or chronic inflammation.

What Does a High or Low Count Mean?

High monocyte counts might suggest chronic infections, certain cancers, or inflammatory diseases. Low counts could indicate immune deficiencies or other blood-related disorders.

How Is the Test Performed?

A small blood sample is taken from a vein, usually in your arm. The sample is then analyzed in a lab to count the monocytes.

What Are Common Causes of Abnormal Results?

Changes in monocyte levels can be due to infections, autoimmune diseases, or reactions to certain medications. Genetic or inherited conditions may also affect monocyte counts.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Monocyte counts are important for diagnosing and managing various health conditions, including infections, inflammatory diseases, and certain cancers. They help doctors assess immune function and guide treatment decisions.

Short name

Monocyte Blood Count

Frequently asked questions

What does a high monocyte count usually indicate?
A high monocyte count may signal chronic infections, inflammatory diseases, or conditions like tuberculosis, certain cancers, or autoimmune disorders.
What could cause a low monocyte count?
A low monocyte count might be linked to immune deficiencies, bone marrow disorders, or certain medications that suppress white blood cell production.
Is there anything I should do before the test?
No special preparation is needed, but inform your doctor about any medications or recent illnesses, as they may affect results.
  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