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Neutrophil-to-Lymphocyte Ratio (NLR) in Whole Blood

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

This test compares the number of neutrophils (a type of white blood cell) to lymphocytes (another type of white blood cell) in your blood. It’s often used to assess inflammation or infection.

Quick summary

["NLR helps doctors check for immune response or possible infections."]

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

Key facts at a glance

LOINC
98123-3
Short code
Neut fMLP stim DHR Pnl Patient FC
Synonyms
Neut fMLP stim DHR Pnl Patient FC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
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 Neutrophil-to-Lymphocyte Ratio Used For?

Doctors may use NLR to evaluate conditions like infections (such as pneumonia or sepsis), inflammatory diseases (like rheumatoid arthritis), or even cancer. It can also help monitor treatment progress or response to illness.

How Is This Test Performed?

A small blood sample is drawn from your arm. The lab then analyzes the blood cells to determine the ratio of neutrophils to lymphocytes. No special preparation is needed.

What Do the Results Mean?

Higher NLR may suggest an active infection or inflammation, while lower NLR could indicate a less aggressive immune response. However, results depend on your overall health and medical history.

Common Reasons for Testing NLR

Your doctor might order this test if you have symptoms like fever, fatigue, or unexplained weight loss, or if you’re recovering from surgery or an illness.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: NLR is a simple, non-invasive marker that helps doctors assess immune function and inflammation. It’s often used alongside other tests to guide treatment decisions, especially in acute or chronic conditions.

Short name

NLR (Blood)

Frequently asked questions

Why did my doctor ask for this test?
Your doctor may have noticed signs of infection, inflammation, or immune response in your bloodwork and wanted to check the balance between two key white blood cell types.
Is there anything I should do before the test?
No special preparation is needed. You can eat, drink, or take medications as usual on the day of the test.
Will the results affect my treatment?
Possibly. Higher NLR might prompt further testing or adjustments to your treatment plan, depending on your symptoms and overall health. Always discuss results with your doctor.
  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