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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, two key immune cells. It’s often used to assess inflammation or infection levels in your body.

Quick summary

["NLR helps doctors check for inflammation or infection by comparing two important immune cells."]

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

Key facts at a glance

LOINC
72998-8
Short code
Losartan (neut) IgG SerPl Ql FC
Synonyms
Losartan (neut) IgG SerPl Ql 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
CPT
82784
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 and lymphocytes are types of white blood cells that fight infections and inflammation. NLR compares their numbers—higher ratios may suggest active inflammation, infection, or other health concerns. This test is sometimes ordered alongside other blood tests to guide treatment decisions.

Why Might You Need This Test?

Your doctor may request an NLR test if you have symptoms like fever, fatigue, or signs of infection (e.g., sore throat, cough). It can also help monitor conditions like cancer, autoimmune diseases, or chronic inflammation. Some studies explore its role in heart disease or COVID-19 recovery.

How Is the Test Done?

A blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab, where neutrophils and lymphocytes are counted. Results are expressed as a ratio (e.g., 1.5:1). No special preparation is needed, but fasting may not affect this test.

What Do the Results Mean?

Interpretation depends on your overall health and symptoms. Elevated NLR (above typical ranges) may signal inflammation, infection, or stress. Lower NLR could indicate immune suppression or certain immune disorders. Your doctor will discuss results with you in context of your medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: NLR’s Role in Healthcare

Short name

NLR

Frequently asked questions

What causes a high NLR?
High NLR is often linked to infections (e.g., bacterial or viral), chronic inflammation, or conditions like cancer, diabetes, or heart disease. It may also rise during stress or trauma. Always check with your doctor, as causes vary widely.
Can NLR replace other blood tests?
No, NLR is one tool among many. It’s often used alongside tests like CRP (C-reactive protein) or white blood cell counts. Doctors combine results to diagnose or monitor conditions accurately.
Does diet affect NLR?
Diet may influence inflammation indirectly, but NLR itself isn’t affected by food. Avoiding extreme diets or supplements isn’t necessary unless advised by 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