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    Neutrophil-Lymphocyte Ratio (NLR) Calculator

    Calculates neutrophil-lymphocyte ratio.


    Launched during COVID-19 crisis.


    Using either the absolute count or the percentage/relative count from a CBC with differential will yield the same NLR result.

    When to Use
    Why Use

    The NLR may help detect occult physiologic stress in patients with similar symptoms. One example that PulmCrit uses is differentiating a simple viral syndrome from bacteremia or sepsis (a viral syndrome might create very mild signs of physiologic distress while sepsis would create severe physiologic distress).

    The NLR appears to increase with any physiologic stress; it would not help differentiate hemorrhagic shock from septic shock, for example. 

    While there is not formally agreed upon cutoffs for NLR, PulmCrit provides some basic ranges to help provide some guidance: 

    • A normal NLR is roughly 1-3.

    • An NLR of 6-9 suggests mild stress (e.g. a patient with uncomplicated appendicitis).

    • Critically ill patients will often have an NLR of 9 or higher (occasionally reaching values close to 100).

    The NLR does appear to have good discriminant function evaluating patients for possible appendicitis, as well as prognostication for several conditions including pulmonary embolism.

    The NLR may be skewed for several reasons, including steroid use, an active hematologic disorder, and possibly HIV (with this predominantly concerning chronic lymphopenia).

    The NLR appears to be a reasonably good marker of "physiological stress" in the body, and in many studies performs better than more commonly used tests like the standard white blood cell count (WBC).

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    Creator Insights
    Dr. Roman Zahorec

    About the Creator

    Roman Zahorec, MD, CSc, is professor in the department of anesthesiology and intensive care medicine at the Institute of Oncology St. Alžbety in Slovakia. He is also the head of the department and is a member of the ethics committee. Dr. Zahorec's primary research is focused on anesthesia management in oncology cases and predictive outcomes in critically ill patients.

    To view Dr. Roman Zahorec's publications, visit PubMed

    Are you Dr. Roman Zahorec? Send us a message to review your photo and bio, and find out how to submit Creator Insights!
    MDCalc loves calculator creators – researchers who, through intelligent and often complex methods, discover tools that describe scientific facts that can then be applied in practice. These are real scientific discoveries about the nature of the human body, which can be invaluable to physicians taking care of patients.
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