Neutrophil Count

Aka: Neutrophil Count, Neutrophil, Absolute Neutrophil Count, Neutrophilic Leukocyte, Polymorphonuclear Leukocyte, PMN, PMN Count, Neutrophilia, Stress Leukocytosis, Band Neutrophil, Left Shift, Demargination

1. Definitions
   1. Neutrophil
      1. Scavenger, granulocytic White Blood Cell, among the first immune cell to respond to infection sites
      2. As with other Phagocytes (Macrophages), Neutrophils engulf foreign material and organisms and lyse them
   2. Left Shift
      1. Increased number of immature Neutrophils (band forms)
      2. Suggests acute inflammation
2. Characteristics
   1. Neutrophils form in Bone Marrow from Myeloblasts as with other Granulocytes (Basophils, Eosinophils, Monocytes)
   2. Neutrophils are scavenger, granulocytic White Blood Cell, among the first immune cell to respond to infection sites
   3. Neutrophils are short-lived cells that survive for only 1-2 days
   4. Function: Primary defense against Bacterial Infection
      1. Neutrophils engulf foreign material (Phagocytosis) and organisms and lyses/digests them
      2. Responds to several sources of chemotaxins
         1. Macrophage released Interleukin
         2. Basophil and Mast Cell released Histamine
         3. C-Reactive Protein Induced Complement Activation
   5. Morphology on Blood Smear
      1. Granulocyte with neutral staining on Wright Stain
      2. Nucleus with 3 to 5 lobes connected by thin chromatin
      3. Cytoplasm with fine granules
         1. Granules are Lysosomes that contain enzymes that lyse Bacteria and other organisms
3. Interpretation: Normal Count
   1. Range: 50-70% of White Blood Cells
   2. Bands: 2-6% of White Blood Cells
   3. Absolute Neutrophil Count (ANC) >1500 Neutrophils/mm3
4. Causes: Decreased Neutrophils
   1. See Neutropenia
5. Causes: Increased (Neutrophilia) - ANC > 7500/mm3
   1. Acute Bacterial Infection (and other infections)
   2. Reactive Neutrophilia (Physiologic Increase, Demargination)
      1. Release of cells in marginal pool
      2. Mediated by stress (Stress Leukocytosis)
         1. Exercise
         2. Seizures
         3. Anxiety
         4. Epinephrine
         5. Tobacco use
         6. Post-operative state
   3. Tissue Injury
      1. Myocardial Infarction
      2. Burn Injury
      3. Hypersensitivity Reaction
   4. Chronic Inflammation
      1. Rheumatic disease
      2. Inflammatory Bowel Disease
      3. Vasculitis
      4. Chronic Hepatitis
   5. Metabolic condition
      1. Acute Renal Failure
      2. Eclampsia
      3. Ketoacidosis
   6. Myeloproliferative disorder
      1. Myelocytic Leukemia
      2. Myeloid metaplasia
      3. Polycythemia Vera
   7. Miscellaneous causes
      1. Hemolytic Anemia
      2. Acute Hemorrhage
      3. Splenectomy (Leukocytosis may persist for months)
      4. Immune Thrombocytopenia
   8. Neoplasms
      1. Metastatic cancer
   9. Congenital
      1. Down Syndrome
      2. Leukocyte adhesion deficiency
   10. Medications
       1. Corticosteroids
       2. Lithium
       3. Beta agonists
       4. Epinephrine
       5. Colony-Stimulating Factors
6. Evaluation: Neutrophilia (Neutrophils >7000/mm3)
   1. See Leukocytosis
   2. Consider history and potential causes
      1. Travel and contagious contacts
      2. Social history
      3. New medications
   3. Diagnostics (consider)
      1. Infection source evaluation
         1. Urinalysis
         2. Chest XRay
         3. Lumbar Puncture
         4. Blood Cultures (2 sets or if SBE suspected, 3 sets)
      2. Acute phase reactants
         1. Erythrocyte Sedimentation Rate (ESR)
         2. C-Reactive Protein (C-RP)
         3. Procalcitonin
      3. Other labs
         1. Rheumatologic studies (e.g. Antinuclear Antibody)
7. References
   1. Wilson (1991) Harrison's Medicine, McGraw, p. 360-1
   2. Riley (2015) Am Fam Physician 92(11):1004-11 [PubMed]