Biomarker · Blood cells

Neutrophils

Also known as: neutrophil count, ANC, absolute neutrophil count, polymorphs

The most numerous white blood cell and the first responder to bacterial infection. The absolute neutrophil count from the differential is the number clinicians use to judge infection risk during chemotherapy and to recognise a bacterial cause of illness.

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Also known as
neutrophil count, ANC, absolute neutrophil count, polymorphs
Units
×10⁹/L
Measured by
Full blood count, CRP test

What it is and what it does

Neutrophils are short-lived cells that leave the marrow, circulate for hours and then move into tissues to engulf and kill bacteria and fungi. The marrow keeps a large reserve that can be released within hours, which is why the count climbs so fast in bacterial infection, after injury and with corticosteroids. A very low count (neutropenia) leaves the body open to serious infection: a fever in someone with a count below about 0.5 ×10⁹/L is treated as an emergency (neutropenic sepsis).

Why it may be higher

  • Bacterial infection, abscess, sepsis
  • Tissue injury: surgery, burns, heart attack, gout flares
  • Corticosteroids, lithium, colony-stimulating factors
  • Smoking, stress, strenuous exercise, pregnancy and labour
  • Chronic myeloid leukaemia and other myeloproliferative disorders

Why it may be lower

  • Chemotherapy and radiotherapy
  • Medicines such as clozapine, carbimazole, sulfasalazine, methotrexate
  • Overwhelming sepsis, viral infections
  • Bone-marrow failure, B12 or folate deficiency
  • Autoimmune neutropenia; benign ethnic neutropenia

A high or low value can be associated with several different situations. The result is interpreted with other results, symptoms, history and clinical findings.

What can affect the result

  • Exercise and adrenaline release shift cells from vessel walls into the circulation for a short time
  • Time since a steroid dose
  • Ethnic background changes the reference interval
Reference ranges. Reference intervals for this marker depend on the laboratory, the assay, the units, age, sex and pregnancy. Interpret a result against the interval printed on the laboratory report, not against a figure from the internet.
Educational content. A biomarker page explains what a substance is and why its level can change. It cannot determine the cause of your result: interpret a result using the range supplied by the laboratory that performed the test, with the clinician who ordered it.