Summary
Neutrophilia may occur with or without an elevated white blood cell (WBC) count (leukocytosis). Neutrophilia without leukocytosis is defined as an elevated circulating neutrophil count (>7.7×10⁹/L) in adults with a normal total WBC count of <11×10⁹/L.[1] An elevated total WBC count (>11×10⁹/L) and an absolute neutrophil count >7.7×10⁹/L is defined as a neutrophilic leukocytosis.[1]
The absolute neutrophil count can be estimated by multiplying the total WBC count by the percentage of polymorphonuclear cells and band forms (immature neutrophils have a band-shaped nucleus).[2]
The terms granulocytosis and neutrophilia are often used interchangeably, although granulocytosis also includes elevations in eosinophils and basophils.
The terms hyperleukocytosis and leukaemoid reaction are reserved for total leukocyte counts of >50×10⁹/L. Leukaemoid reaction may mimic leukaemia, but has a non-malignant aetiology.
Neutrophilia results from:
Increased production of neutrophils
Demargination (process of neutrophils entering the peripheral circulation from areas of intravascular marginated polymorphonuclear cell pools), or
Decreased egress (outwards migration) of neutrophils from peripheral circulation to the tissues.[Figure caption and citation for the preceding image starts]: NeutrophiliaFrom the collection of T. George, MD [Citation ends].
Epidemiology
Many diverse factors contribute to the development of neutrophilia, so defining the population at risk is difficult. Individuals carrying a Duffy null (Fy(a-b-)) phenotype, which is protective against Plasmodium vivax infection of red blood cells, have a lower absolute neutrophil count (mean difference 700 cells/microlitre) than other individuals and may therefore be considered to have neutrophilia at a lower count.[3]
The neutrophil count changes with age, with the highest counts seen in the first few days after birth, then decreasing rapidly. Neutrophil counts approach adult levels around age 10. Lifestyle factors, including exercise levels, stress, and smoking status, influence the risk of neutrophilia.
Differentials
Common
- Infection
- Inflammatory conditions
- Chronic myeloid leukaemia (CML)
- Essential thrombocythaemia
- Polycythaemia vera
- Primary myelofibrosis
- Pregnancy
Uncommon
- Platelet clumping
- Cryoglobulinaemia
- Anaemia
- Solid tumour malignancy
- Bone marrow infiltration
- Heat stroke
- Chronic bone marrow stimulation
- Asplenia
- Sweet's syndrome
- Drug-induced haematopoiesis
- Chronic neutrophilic leukaemia
- Myelodysplastic syndrome
- Acute myeloid leukaemia
- Hereditary neutrophilia
- Pelger-Huet abnormality
- Amegakaryocytic thrombocytopenia
- Trisomy 21 (Down's syndrome)
- Leukocyte adhesion deficiency type I
- Familial cold autoinflammatory syndrome
- Chronic idiopathic neutrophilia
- Stress-induced demargination
- Drug-induced demargination
- Drug-induced decreased egress
Contributors
Authors
Devon Chabot-Richards, MD
Professor of Pathology
University of New Mexico Health Sciences Center
Albuquerque
NM
Disclosures
DCR declares that she is a board member for New Mexico Society for Clinical Oncology, and lectures and takes part in educational events for the College of American Pathologists. She receives royalties from Elsevier.
Tracy I. George, MD
Professor of Pathology
University of New Mexico Health Sciences Center
Albuquerque
NM
Disclosures
TIG declares that she has no competing interests.
Acknowledgements
Dr Devon Chabot-Richards and Dr Tracy I. George would like to gratefully acknowledge Dr Holbrook Kohrt, a previous contributor to this topic.
Disclosures
HK declares that he has no competing interests.
Peer reviewers
Carla Wilson, MD, PhD
Professor
Department of Pathology
University of New Mexico Health Sciences Center
Albuquerque
NM
Disclosures
CW declares that she has no competing interests.
Sherrie Perkins, MD, PhD
Professor of Pathology
Medical Director of Hematopathology
University of Utah Health Sciences and ARUP Laboratories
Salt Lake City
UT
Disclosures
SP declares that she has no competing interests.
John Reilly, BSc, MD, FRCP, FRCPath
Consultant Haematologist
Royal Hallamshire Hospital
Professor
University of Sheffield
Sheffield
UK
Disclosures
JR declares that he has no competing interests.
Priyanka Mehta, MD, MRCP, FRCPath
Consultant Haematologist
University Hospital Bristol
Bristol
UK
Disclosures
PM declares that she has no competing interests.
References
Key articles
Hoffman R, Benz E, Silberstein L, et al. Hematology basic principles and practice. 7th ed. Philadelphia, PA: Elsevier Churchill Livingston; 2017.
Reference articles
A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
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