Neutrophil-to-Lymphocyte Ratio (NLR) in Serum/Plasma
This test measures the ratio of your white blood cells’ neutrophils to lymphocytes, two key immune cells. It helps assess inflammation or infection levels in your blood.
["NLR can indicate whether your body is fighting infection or inflammation more than usual."]
Key facts at a glance
- LOINC
- 6501-1
- Short code
- N men sg C Ag Spec Ql IF
- Synonyms
- N men sg C Ag Spec Ql IF
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- if
- 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 respond quickly to infections or injuries. Lymphocytes are another type that play a role in long-term immunity. The NLR compares these two cell counts. A higher ratio may suggest acute inflammation or infection, while a lower ratio might indicate chronic conditions or immune suppression.
Why Is This Test Done?
Doctors may order this test to evaluate symptoms like fever, fatigue, or unexplained weight loss. It can also help monitor conditions like cancer, autoimmune diseases, or infections. Some studies explore its role in predicting outcomes in heart disease or other chronic illnesses.
How Is the Test Performed?
A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where the white blood cells are analyzed. The NLR is calculated by dividing the neutrophil count by the lymphocyte count.
What Do Results Mean?
Results are not given in a fixed range because they vary by health status and individual. A higher NLR might suggest acute inflammation or infection, while a lower NLR could indicate chronic conditions or immune suppression. Your doctor will interpret results in the context of your overall health and symptoms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Higher NLRs are often associated with acute infections, inflammatory diseases, or conditions like sepsis. Lower NLRs may be seen in chronic illnesses, immune disorders, or certain cancers. While NLR is not a definitive diagnostic tool, it can provide clues about your body’s immune response and help guide treatment decisions.
Short name
NLR (Serum/Plasma)
Frequently asked questions
What causes a high neutrophil-to-lymphocyte ratio?
What causes a low neutrophil-to-lymphocyte ratio?
Can this test replace other blood tests?
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