Neutrophils
Also written as: ANC, absolute neutrophil count, polys, segs
The most common white blood cell and the immune system's first responder to bacteria.
What it measures
The number of neutrophils in the blood, reported as an absolute count and as a percentage of all white cells. Neutrophils are the most numerous white blood cells and the first to arrive at sites of infection or injury.
Why a doctor orders it
It comes as part of a complete blood count with differential, the breakdown of white cell types. Clinicians look at it when considering infection or inflammation, and to monitor people on treatments known to lower white cell counts.
What is generally associated with a higher result
Broadly associated with bacterial infections, inflammation, tissue injury, and physical or emotional stress. Smoking, corticosteroid medicines, recent strenuous exercise, and late pregnancy also raise the count without any infection present.
What is generally associated with a lower result
Broadly associated with some viral infections, certain medications, and vitamin shortages. Many healthy people of African or Middle Eastern ancestry have a naturally lower baseline count, an inherited pattern with no known health consequence.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- Recent strenuous exercise or physical stress, which raises the count for hours
- Corticosteroid medicines, which raise it
- Smoking
- A recent vaccination or minor illness
- Pregnancy, which raises it normally
- Time of day
Questions to take to your appointment
- Could a recent illness, vaccination, or stressful event explain a shift?
- Do you know my usual baseline - could this simply be normal for me?
- Should we be looking at the absolute count rather than the percentage?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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