Zahorec index or Neutrophil-to-lymphocyte ratio, valid biomarker of inflammation and immune response to infection, cancer and surgery.

Background: For many years, the physicians are searching for easily measurable marker of immune response to the stress and inflammation. More than, 20 years ago Zahorec (2001) proposed neutrophil-to-lymphocyte ratio (NLR) as an easy available and valid biomarker of inflammation, stress, and activation of immune system.

Methods: In this narrative review we focused on the utility of neutrophil-to-lymphocyte ratio (Zahorec's index) in clinical practice of general medicine (inflammation and infection), intensive medicine (sepsis), oncology (prediction of prognosis in cancer of solid organs), surgery and perioperative medicine (diagnosis of complications, and prediction of clinical outcome).

Results and conclusion: We provide many evidences of clinical research which confirm that Neutrophil-to-lymphocyte ratio is a very sensitive marker of inflammation, stress reliable and valid parameter in everyday clinical practice. NLR (Zahorec index) is an effective tool for diagnosis of infection and severity of disease of variable etiologies. NLR reflect the grade of inflammation in cancer disease, which has a significant impact on the prognosis of cancer patients. Zahorec index should be used routinely in emergency medicine, surgery and perioperative medicine as a marker of the severity of affliction, infection, and complications in general. NLR may help physicians in decision making process for early diagnosis and therapy. NLR should be investigated frequently in acute states (sepsis, shock, peritonitis, stroke, trauma) on a daily basis, in subacute states few times per week (during hospital stay), and few times per year in chronic disease (cancer, diabetes mellitus, ischemic heart disease, psychiatry disorders). NLR has a deep biological sense connecting together function of three suprasystems: immune, endocrinne and autonomous nervous system (Tab. 2, Fig. 3, Ref. 86).