Neutrophils and lymphocytes are types of white blood cells that play a critical role in protecting the body from infections, among other roles. White blood cells are a key component of the body’s response to stress and coordinate the process known as inflammation.
Counting the number of neutrophils and dividing by the number of lymphocytes, a ratio termed the "neutrophil to lymphocyte ratio" (NLR), is one way to measure inflammation within the body.
Neutrophils are the first responders in inflammation and they quickly arrive on the scene and get to work in a process known as innate immunity. Lymphocytes have a slower but still important response to inflammation and tend to arrive after neutrophils as part of the adaptive immune response.
The NLR works based on the knowledge that increasing levels of stress hormones produced by the body will drive the neutrophil levels up and the lymphocyte levels down. As a result, this simple ratio can be a marker that illustrates the stress levels that the body is experiencing during acute illness.
The changes in neutrophil and lymphocyte cell levels have been associated with the severity of illness in a variety of conditions including infections, cancer, and even major cardiovascular events.
Measuring levels of white blood cells is done using a common blood test called a complete blood count (CBC), which can identify the specific types of white blood cells circulating in the blood. When a complete blood cell count with differential is performed, the instrument used can identify and count neutrophils and lymphocytes.
With this information in hand, healthcare providers can calculate the NLR ratio and gain insight into the inflammatory status of the body. A normal NLR will generally fall between a level of 1 to 4, though this value may vary from person to person.
An NLR level above 6 is considered an indicator of severe inflammation. In severe illness, the NLR may go as high as 100.
During episodes of stress, such as when the body is responding to an infection, the NLR can become abnormally elevated and climb to levels as high as 100. Therefore, the NLR is best thought of as a marker of inflammation that may help physicians determine the severity of an ongoing stress in the body.
For example, the NLR is associated with severe infection with COVID-19 among other infectious diseases. In other studies, an elevated NLR was able to identify individuals likely to have more severe cardiovascular and respiratory diseases.
Some studies have also investigated the role of the NLR in the prognosis for people with cancer undergoing chemotherapy treatment. The NLR is a predictor of adverse outcomes like weight loss and cachexia (weight loss and muscle wasting) in people undergoing chemotherapy.
The NLR may be most useful for predicting the severity of infection. Studies have shown that using the NLR in a hospital emergency department may aid in identifying and more promptly treating bloodstream infections, known as bacteremia.
At the same time, the NLR can be used to assist in the diagnosis of appendicitis (inflammation of the appendix, the tube-shaped pouch on the right side of the abdomen that extends from the large intestine). An elevated NLR has been shown to correspond to the severity of appendicitis and may be useful in determining the need for surgery.
It is important to note that the NLR is just one measure and a full evaluation of the NLR in the context of the specific disease is necessary before making any decisions.
There are many potential causes of an elevated NLR. As a result, the NLR is used most often as a way to evaluate the severity of disease and how the body may be responding to infection.
Conditions with an elevated NLR include:
The neutrophil to lymphocyte ratio is a relatively new measure of inflammation within the body that is still gaining acceptance. Growing clinical evidence has highlighted the utility of this measure, however, it may not always apply to every disease.
Interpretation of the NLR in the context of other laboratory and blood tests is needed in order to properly assess the body's response to acute illness. For this reason, measuring the NLR should be done with the assistance of a healthcare provider who can help interpret the findings alongside other measures.
In some cases, the NLR may not be accurately measured. For example, certain cancers such as leukemias may skew the measurement of the NLR. In addition, certain treatments such as chemotherapy or bone marrow or stem cell transplants can also alter the NLR and limit its predictive ability.
High neutrophils and low lymphocytes together represent an elevated NLR ratio. The elevation can be caused by many different conditions and may be an indicator of a severe infection, an inflammatory disorder, or cancer.
High levels of neutrophils may indicate a severe infection or stress on the body. Low levels of lymphocytes may also reflect severe stress and the release of stress hormones.
If you see high neutrophils and low lymphocytes on your lab report, discuss this finding with your healthcare professional. While it may indicate inflammation, it needs to be interpreted with consideration of your overall health, symptoms, and other diagnostic findings. As with any lab test, it is only one tool in diagnosing illness.
When the body is placed under severe physiologic stress the levels of neutrophils may be high and lymphocytes may be low. Inflammation seen in many different conditions can produce this result.
The release of natural stress hormones contained within the body regulates the levels of neutrophils and lymphocytes within the body. These hormones help the body initiate the inflammatory response and respond to and fight infection, cancer, and other diseases.
The lymphocytes are a specific population of white blood cells that play a crucial role in fighting infections, producing immunity, and controlling abnormal cells in our body. When the lymphocyte levels are low, this indicates that the body may be experiencing severe stress.
No, high neutrophils are not a reliable indicator of cancer. Diagnosing cancer requires a combination of blood tests, imaging, and tests on organ tissue .