Lab Test: Neutrophil Count
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- Measurement of neutrophils in blood for the evaluation and management of immunologic, hematologic, and neoplastic disorders
- Represent the most abundant of granulocytes
- Neutrophils kill bacteria and organisms by a process of phagocytosis and release of enzymes
- Adults:
- Relative: 40% to 70%
- Absolute: 1.8-7.7 x 103 cells/microL
- Children, 1 to 4 years:
- Absolute: 1.5-8.5 x 103 cells/microL
- Children, 6 years:
- Absolute: 1.5-8 x 103 cells/microL
- Children, 10 years:
- Absolute: 1.8-8 x 103 cells/microL
- Chronic benign neutropenia
- Chronic benign neutropenia (CBN) in infancy and childhood is typically first diagnosed at an age of less than 14 months with neutrophil counts dropping below 200/mm3 and is usually accompanied by normal bone marrow with a low risk of severe bacterial infection. When an absolute neutrophil count (ANC) remains below 500 to 1000/mm3 for 3 to 4 months without clinical indicators such as serious infection, a diagnosis of CBN may be established.
- Although the severity of neutropenia often varies from case to case in childhood, an ANC less than 500/mm3 may suggest CBN. Additionally, ANC values may fluctuate between zero and normal; therefore, during an acute infection, a patient with CBN may exhibit a rise in ANC to what is otherwise a normal value.
- Neutrophil counts below 1.5 x 109/L (in adults and children over 1 year) may be seen in certain ethnic groups (e.g., blacks and Middle Eastern) when the patient is otherwise healthy and without repeated infections.
- Cyclic neutropenia
- A neutrophil count less than 200/mm3 every 21 days is consistent with cyclic neutropenia. Most patients (70%) with cyclic neutropenia experience repetitive infectious complications every 21 days in conjunction with regularly occurring neutropenic episodes that may persist for 3 to 10 days.
- Obtain neutrophil blood counts 2 to 3 times per week for up to 8 weeks to identify the 21-day cycle typifying cyclic neutropenia and to identify nadirs lasting 3 to 5 days.
- Drug-induced neutropenia
- Medications account for about 70% of all cases of neutropenia and are associated with mortality of up to 25%.
- A severe decline of neutrophils in patients receiving antithyroid medications, antibiotics, anticonvulsants, or clozapine may indicate drug-induced neutropenia and is associated with a high incidence of infection.
- Febrile neutropenia in cancer patients (neutropenia severity scales according to the National Cancer Institute (NCI)):
- Mild neutropenia: <1500/mm3
- Moderate neutropenia: <1500-1000/mm3
- Severe neutropenia: <1000-500/mm3
- Life-threatening or disabling neutropenia: <500/mm3
- Cancer patients with severe neutropenia (less than 0.1 x 109/L) and no sign of fever or infection should be considered at high risk for developing fever, infection, and serious complications.
- Neutropenia of less than 7 days' duration or that is expected to resolve within 10 days is a low risk finding for severe infection in febrile neutropenic cancer patients.
- Infectious Diseases Society of America (IDSA) guidelines state that neutrophil counts are critical for determining the discontinuation of antibiotic therapy in cancer patients. When a neutrophil count reaches 500 cells/mm3 or greater for 3 consecutive days and the patient is afebrile for 48 hours or more, antibiotic therapy may be safely discontinued.
- In patients with small-cell lung cancer, the probability of developing fever is approximately 10% per day for each day that patients have had a neutrophil count of less than 0.5 x 109/L.
- One of the most important prognostic factors in a patient receiving chemotherapy is the recovery of the neutrophil count. Neutropenia also may exacerbate the adverse effects of chemotherapy.
- Neonatal congenital neutropenia
- In neonates from birth to 5 days, a neutrophil count equal to or less than 500/microL may indicate a type of congenital neutropenia resulting from pregnancy-induced hypertension.
- Typically, this type of neutropenia resolves within 72 hours to 5 days.
- Neutropenia
- Neutropenia may be classified as mild (1-1.5 x 103/microL, moderate (0.5-1 x 103/microL), or severe (less than 0.2-0.5 x 103 microL).
- Normal neutrophil counts vary in certain ethnic groups. Reportedly, 25% to 50% of individuals of blacks have a normal neutrophil count that is lower than the standard normal of 1.5 x 103 microL. Similar findings have been noted in individuals of Middle Eastern descent.
- Transient instances of neutropenia in infants and children tat resolves spontaneously within 2 weeks are rarely associated with clinical problems. Chronic neutropenia may be considered in the same population when neutrophil counts remain abnormally low for more than 6 months.
- White blood cells (WBC) are divided into granulocytes and nongranulocytes.
- Granulocytes include neutrophils. Because of their multilobed nuclei neutrophils are sometimes referred to as polymorphonuclear leukocytes (PMNs or "polys"). The normal range for absolute counts depend on age, sex, and ethnicity. Neutrophils are produced in 7 to 14 days, and exist in the circulation for only 6 hours.
- The primary function of the neutrophil is phagocytosis (killing and digestion of bacterial microorganisms).
- Acute bacterial infections and trauma stimulate neutrophil production, resulting in an increased WBC count. When neutrophil production is significantly stimulated, early immature forms of neutrophils often enter the circulation. These immature forms are called band or stab cells. This occurrence, referred to as a "shift to the left" in WBC production, is indicative of an ongoing acute bacterial infection.
- Increased levels may indicate:
- Neutrophilia, physical or emotional stress, acute suppurative infection, myelocytic leukemia, trauma, Cushing syndrome, inflammatory disorders (e.g., rheumatic fever, thyroiditis, rheumatoid arthritis), or metabolic disorders (e.g., ketoacidosis, gout, eclampsia)
- Decreased levels may indicate:
- Neutropenia, aplastic anemia, dietary deficiency, overwhelming bacterial infection (especially in the elderly), viral infection (e.g., hepatitis, influenza, measles), radiation therapy, Addison disease, or drug therapy such as myelotoxic drugs (as in chemotherapy)
- Collect whole blood.
- Do not use heparin.
- Apply pressure or a pressure dressing to the venipuncture site and assess the site for bleeding.
- Explain the procedure to the patient.
- Tell the patient that no fasting is required.
- Clin Lab Med 2015;35:11-24.
- Briggs C et al. Int J Lab Hematol 2014;36:613-627.
- Mayo Clin Proc 2005;80:923-936.
- LaGow B et al., eds. PDR Lab Advisor. A Comprehensive Point-of-Care Guide for Over 600 Lab Tests. First ed. Montvale, NJ: Thomson PDR; 2007.
- Pagana K, Pagana TJ eds. Mosby's Manual of Diagnostic and Laboratory Tests. 5th Ed. St. Louis, Missouri. 2014.
Description
Reference Range
Indications & Uses
Elevations of neutrophils may be found in the following conditions:
Clinical Application
Procedure
What To Tell Patient Before & After
References
MESH Terms & Keywords
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