Neutrophil-to-Lymphocyte Ratio (NLR) in Serum/Plasma
This test measures the ratio of neutrophils (a type of white blood cell) to lymphocytes (another type of white blood cell) in your blood. It’s often used to help assess inflammation or infection.
["NLR helps doctors gauge your body’s immune response."]
Key facts at a glance
- LOINC
- 108994-5
- Short code
- N men sg C IgG Msmt Ser
- Synonyms
- N men sg C IgG Msmt Ser
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 both types of white blood cells that play key roles in fighting infections. When your body detects an infection or inflammation, the levels of these cells can change. The NLR compares the number of neutrophils to lymphocytes to give a quick snapshot of your immune response.
Why Is This Test Done?
Doctors may order an NLR test to monitor conditions like infections (such as pneumonia or sepsis), inflammatory diseases (like rheumatoid arthritis), or to check how your body is responding to treatment. It can also help assess risk in certain situations, such as before surgery or in cancer care.
How Is the Test Performed?
A small blood sample is drawn from a vein, usually in your arm. The blood is then analyzed in a lab to measure the counts of neutrophils and lymphocytes. The NLR is calculated by dividing the neutrophil count by the lymphocyte count.
What Do the Results Mean?
Results are not given as a specific range because NLR varies widely depending on health status, age, and other factors. Instead, doctors compare your NLR to your own baseline or to reference ranges provided by the lab. High NLR may suggest inflammation or infection, while low NLR might indicate immune suppression or other conditions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
High NLR levels are often associated with active infections, sepsis, or chronic inflammatory diseases. Doctors may use NLR as a quick, non-invasive tool to monitor disease progression or treatment effectiveness. It can also help guide decisions in settings like cancer care, where immune response is critical. However, NLR alone is not diagnostic—it’s typically used alongside other tests and clinical findings.
Short name
NLR (Serum/Plasma)
Frequently asked questions
What causes a high NLR?
What causes a low NLR?
Is NLR the same as a white blood cell count?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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