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Functional Blood Chemistry Manual


Marker Name: Neutrophils


Lab reference range:
Relative: 49–74%
Absolute: 1.4 – 7.0 x103/µL

Functional reference range:
Relative: 40–60%
Absolute: N/A


A neutrophil is one of the white blood cells that circulates in the bloodstream. It is also a type of granulocyte, which is a cell that releases enzymes during the immune response to infection or allergen. Granulocytes include neutrophils, eosinophils, and basophils and are distinguished from lymphoid white blood cells, namely B and T lymphocytes, plasma cells, and natural killer cells.1

Neutrophils are the most common phagocyte, which is a cell that ingests foreign particles or cells (e.g., microorganisms).2 As such, neutrophils are integral components of the innate immune system and are the first cells recruited to sites of infection or inflammation.3 They are attracted to these sites through a variety of cytokines, chemokines, and other chemotactic factors. Once at the site of infection, neutrophils internalize and destroy foreign microbes. As neutrophils move towards their microbial targets, they release neutrophil extracellular traps (NETs), which can themselves capture and kill microbes.4 Ideally, NETs should protect tissue from destruction by localizing the effect of proteases; neutrophils can mediate tissue damage in several inflammatory disorders.5

White blood cells—including neutrophils—red blood cells, and platelets are formed from multipotent stem cells within the bone marrow. Granulocyte colony-stimulating factor (G-CSF) stimulates the proliferation, maturation, and function of neutrophils, with virtually no effect on other granulocytes or monocytes.5 Neutrophils normally spend four to five days in the last stage of cell division before entering the bloodstream.6 Once in the bloodstream, human neutrophils survive for approximately five days.7 At that time, they undergo spontaneous apoptosis and neutrophil senescence, which renders them unable to respond to chemoattractants.8

An abnormally high number of neutrophils in the blood is called neutrophilia. The most common cause of neutrophilia is an acute bacterial infection, especially certain bacteria including Pneumococcus, Staphylococcus, and Clostridium species.9 Certain viruses, fungi, and parasites can also increase the number of neutrophils in the bloodstream. Inflammatory conditions, such as rheumatoid arthritis and inflammatory bowel disease, are often associated with increased neutrophil counts. Conversely, anti-inflammatory drugs, specifically glucocorticoids (e.g., prednisone) may increase the absolute neutrophil count.10 Many physiological stressors have been shown to cause elevated neutrophil levels from trauma, thermal injury, and myocardial infarction to vigorous exercise and cigarette smoking.9

An abnormally low neutrophil count is called neutropenia. Neutropenia may occur during a severe infection or soon afterwards. It may be caused by certain cancers or by cancer treatment (e.g., chemotherapeutic agents). A number of drugs from a wide assortment of drug classes have been shown to diminish neutrophil counts. Certain cancers, myelodysplastic syndrome, and aplastic anemia also cause neutropenia.11

A basic complete blood count (CBC) simply provides quantities of circulating cells in the bloodstream including red blood cells, white blood cells, and platelets. To obtain a neutrophil count, the CBC must be ordered with a differential, which tells the laboratory to provide a count of individual white blood cell types. If a manual differential is ordered, the lab will also report the number of segmented neutrophils and banded neutrophils.12


High in:13-15

  • Normal pregnancy
  • Transient elevation during labor and delivery
  • Normal infancy
  • Cigarette smoking
  • Acute infection (especially bacterial but also certain viral and fungal infections)
  • Noninfectious inflammation
    • Gouty arthritis
    • Acute glomerulonephritis
    • Rheumatic fever
    • Anaphylaxis
    • Collagen-vascular diseases
  • Acute stress
    • Severe burns
    • Intestinal obstruction
    • Myocardial infarction
    • Cardiopulmonary bypass surgery
    • Severe asthma attack
  • Myeloproliferative disorders
  • Metabolic disorders
    • Diabetic ketoacidosis
    • Preeclampsia
    • Uremia
  • Poisoning (e.g., lead, mercury, turpentine, insect venom)
  • Acute hemorrhage
  • Cancers of the blood (e.g., chronic myeloid leukemia, polycythemia vera)
  • Solid tumor cancers (e.g., squamous cell cancers)
  • Drugs
    • Glucocorticoids
    • Recombinant granulocyte colony-stimulating factor
    • Catecholamines
    • Lithium

Low in:16-18

  • Nutritional deficiency (e.g., vitamin B12, folate, copper)
  • Congenital neutropenia (e.g., benign ethnic neutropenia)
  • Infection (e.g., HIV, sepsis)
  • Post-infectious neutropenia
  • Autoimmune neutropenia
    • Primary autoimmune
    • Secondary autoimmune
    • Felty syndrome
  • Myelodysplastic syndromes
  • Cancers of the blood (e.g., acute myeloid leukemia, lymphoma)
  • Aplastic anemia
  • Paroxysmal nocturnal hemoglobinuria
  • Drugs
    • Chemotherapy
    • Atypical antipsychotics (e.g., clozapine, olanzapine)
    • Antibiotics (e.g., penicillin)
    • Anticonvulsants (e.g., phenytoin)
    • Sulfasalazine
    • Thionamides (e.g., methimazole, propylthiouracil, carbimazole)
    • Ticlopidine
    • Rituximab


High in:

  • Same as conventional indications
  • Bacterial infection

Low in:

  • Same as conventional indications
  • Viral infection


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