5,9 Segmented and Band neutrophiles
Neutrophils are the most numerous white blood cells and the body's first line of defence against bacteria and fungi. They reach a site of infection within hours, engulf microbes and kill them with enzymes and reactive oxygen. The blood test distinguishes mature segmented neutrophils (with a nucleus divided into 2–5 lobes) from younger band neutrophils (with an unsegmented, rod-shaped nucleus). A rise in band forms, a "left shift", signals that the bone marrow is releasing cells early, typically during acute bacterial infection.
Neutrophil maturation and the "left shift"
Neutrophils mature in the bone marrow over about two weeks, passing through myeloblast, promyelocyte, myelocyte, metamyelocyte and band stages to the segmented form. Only band and segmented cells normally appear in the blood, where they circulate for less than a day. Inflammation and bacterial infection release more and younger cells. A band count above about 5–6 %, sometimes with metamyelocytes or myelocytes, is called a left shift. A left shift with a falling total neutrophil count in severe infection is an unfavourable sign.
High neutrophils — neutrophilia
- Bacterial infections, abscesses, sepsis — often with a left shift
- Tissue damage: surgery, burns, trauma, myocardial infarction, pancreatitis
- Corticosteroids, adrenaline, lithium; smoking; obesity; pregnancy; intense exercise or emotional stress
- Chronic inflammation: rheumatoid arthritis, vasculitis, inflammatory bowel disease
- Myeloproliferative neoplasms, especially chronic myeloid leukaemia (very high counts with immature cells and basophilia)
Low neutrophils — neutropenia
| Absolute count (×10⁹/L) | Grade | Risk of infection |
|---|---|---|
| 1.0–1.5 | Mild | low |
| 0.5–1.0 | Moderate | increased |
| < 0.5 | Severe | high |
Causes include viral infections, medicines (chemotherapy, some antibiotics, antithyroid drugs, clozapine, metamizole), vitamin B12 or folate deficiency, autoimmune diseases, an enlarged spleen and bone-marrow disorders. Some healthy people of African or Middle Eastern ancestry have a constitutionally lower count without increased infection risk, known as "Duffy-null associated neutrophil count".
if you have fever of 38 °C or higher while your neutrophil count is low — especially during chemotherapy. Febrile neutropenia is a medical emergency that requires immediate antibiotics.
Discuss persistently high or low neutrophils with a doctor, particularly if other blood counts are abnormal or you have recurrent infections, mouth ulcers, weight loss or night sweats.
References
- Gibson C, Berliner N. How we evaluate and treat neutropenia in adults. Blood. 2014;124(8):1251–1258. doi:10.1182/blood-2014-02-482612
- Hsieh MM, Everhart JE, Byrd-Holt DD, et al. Prevalence of neutropenia in the U.S. population: age, sex, smoking status, and ethnic differences. Ann Intern Med. 2007;146(7):486–492. PMID: 17404350
- Riley LK, Rupert J. Evaluation of patients with leukocytosis. Am Fam Physician. 2015;92(11):1004–1011. PMID: 26760415
- Blumenreich MS. The white blood cell and differential count. In: Walker HK, Hall WD, Hurst JW, eds. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Boston: Butterworths; 1990. Chapter 153. ncbi.nlm.nih.gov/books/NBK261
This article is for general information and does not replace a consultation with a doctor. Laboratory results must be interpreted by a physician together with symptoms and other tests.
Published on 8 May 2024