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Neutrophil-to-Lymphocyte Ratio (NLR) in Serum/Plasma

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

This test measures the ratio of your white blood cells’ neutrophils to lymphocytes in your blood, often used to assess immune response and inflammation.

Quick summary

["NLR helps doctors evaluate infection risk and inflammation levels in your body."]

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

Key facts at a glance

LOINC
101582-5
Short code
NM GI tract Vs PLE W Tc-99m HSA IV
Synonyms
NM GI tract Vs PLE W Tc-99m HSA IV
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
nm
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 (NLR)?

Neutrophils are a type of white blood cell that fight bacterial infections, while lymphocytes help with long-term immunity. This test compares their counts to identify shifts that may signal inflammation, infection, or other health conditions.

Why Is NLR Tested?

Doctors may order NLR testing to monitor conditions like cancer, autoimmune diseases, or infections. It can also guide treatment decisions, especially in acute care settings.

How Is the Test Performed?

A blood sample is drawn, and your white blood cell counts (neutrophils and lymphocytes) are measured. The ratio is calculated automatically from the lab results.

What Does a High or Low NLR Mean?

A higher NLR may indicate infection, inflammation, or stress, while a lower ratio could suggest immune suppression or certain chronic conditions. Interpretation depends on clinical context.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: NLR is a simple, non-invasive marker used to assess immune status and guide treatment, particularly in critical care, oncology, and inflammatory diseases. It complements other tests but is not diagnostic alone.

Short name

NLR (Serum/Plasma)

Frequently asked questions

Why might my doctor request this test?
Your doctor may order NLR testing to evaluate your immune response, monitor chronic conditions, or assess risk during surgery or illness. It’s often used alongside other blood tests for a fuller picture.
What should I expect before or after the test?
No special preparation is needed. You may feel slight discomfort from the blood draw, but it’s quick and safe. Results are typically reviewed within 24–48 hours.
Does NLR have reference ranges?
NLR results are not standardized, so doctors interpret them based on your overall health, symptoms, and other test results. A ratio outside typical ranges may prompt further evaluation.
  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