Neutrophils
Neutrophils are the white cells that tackle bacterial infections first — your immune system's rapid responders, swallowing up bacteria where they invade. A result inside the range on your report is reassuring. The count often rises with a recent infection and settles once you are better, which is very common.
Standard CareWhat is neutrophils?
Neutrophils are the most abundant circulating white blood cells (WBCs) in your bloodstream. They belong to a group of immune cells called granulocytes — named for the tiny granules inside them, packed with germ-fighting chemicals. Their main job is to act as a rapid-response team against bacterial infection. When your tissue is damaged or invaded by bacteria, neutrophils move from the blood into the affected area and engulf and destroy the bacteria — a process called phagocytosis (from the Greek for "eating cell"). Your neutrophil count is measured in billions of cells per litre of blood (×10⁹/L) and is almost always reported as part of a full blood count (FBC). The FBC provides a picture of all three main blood cell types — red cells, white cells, and platelets — from a single blood draw. Within the white cell count, each cell type is broken down individually: this is called the differential count. It reports both an absolute number and a percentage of total white cells for neutrophils, lymphocytes, monocytes, eosinophils, and basophils. When neutrophils are above the reference range (a state called neutrophilia), this most often reflects a bacterial infection or an inflammatory process somewhere in the body. When they are below the range (neutropenia — "poverty of neutrophils"), this can reflect reduced production or increased use, and is worth discussing with your GP.
Why is it tested?
Neutrophil counts are ordered when your GP wants a picture of your immune response. Common reasons include: Suspected infection — particularly bacterial, which typically raises neutrophils. Monitoring a known condition such as an autoimmune disease, inflammatory condition, or blood disorder. Checking whether a medication (some drugs can reduce neutrophil production) is affecting your bone marrow. Investigating unexplained fatigue, fever, or recurrent infections. As part of a routine health check that includes a full blood count. Because neutrophils are one of five white cell types reported together, your GP reads the neutrophil count alongside the total white cell count and the rest of the differential — lymphocytes, monocytes, eosinophils, and basophils. The full picture is more informative than any single number.
Reference range (Australia)
Reference intervals for neutrophils are analyser-specific and can vary between laboratories. The range printed on your own pathology report is the correct reference for your result.
Reference intervals vary between laboratories. Always use the range printed on your own report.
What your result means
A neutrophil count below the reference range is called neutropenia. Mild neutropenia is common and can reflect recent viral illness, certain medications (including some chemotherapy agents, antibiotics, and antithyroid drugs), or normal variation in some people. More marked neutropenia can reduce the body's ability to fight bacterial infection and warrants closer attention. A low result doesn't tell your GP why it's low. Further context, such as your medication list, recent illnesses and other FBC values, helps work out the cause; for a persistent or marked low count your GP may consider whether further assessment is needed. Discuss this with your GP: they will put it together with your history to decide the right next step.
Your neutrophil count sits within the range on your report, suggesting your immune system's bacterial-fighting capacity is currently adequate. Neutrophil levels can fluctuate day to day with minor illness, stress, or exercise, so a single result within range is reassuring but should be read alongside the rest of your FBC. If you have ongoing symptoms such as recurrent infections or unexplained fatigue, your GP may want to track this over time.
A neutrophil count above the reference range on your report is called neutrophilia. The most common cause is a bacterial infection, where the bone marrow steps up production and releases more neutrophils into the circulation to fight it. Other causes include physical or emotional stress, inflammation, certain medications (such as corticosteroids), and, occasionally, conditions affecting the bone marrow itself. A single elevated count in the setting of a recent illness or stress response is often temporary. Your GP can tell you whether it is likely to settle on its own or whether further investigation is needed. They will read this alongside the rest of your FBC and your symptoms.
What can affect your result
Several factors can shift your neutrophil count in either direction, even without an underlying disease. Infection is the most common driver of a raised count. Bacterial infections in particular trigger the bone marrow to produce and release more neutrophils; the count typically falls back to normal once the infection resolves. Viral infections more often raise lymphocytes than neutrophils, so the pattern of the differential can help your GP distinguish the two. Inflammation from any cause — including surgery, injury, or inflammatory conditions such as rheumatoid arthritis — can also raise neutrophils, because the immune response involves the same pathway as an infection response. Stress, both physical (intense exercise, surgery) and emotional, can cause a transient rise in neutrophils due to cortisol releasing stored neutrophils from the bone marrow's reserve. Medications are a well-recognised cause of both high and low counts. Corticosteroids (such as prednisolone) can raise neutrophils; certain antibiotics, antiepileptics, antithyroid drugs, and chemotherapy agents can lower them. Your GP will consider your medication list when interpreting the result. Smoking raises the baseline neutrophil count through chronic low-grade airway inflammation. This is normal variation for people who smoke and does not by itself indicate disease. Bone marrow conditions — less common but important — can either overproduce or underproduce all white blood cells, including neutrophils. These are usually suspected when multiple cell lines are affected, not just neutrophils.
When to act
If your neutrophil count is above or below the reference range on your report, that is worth discussing with your GP. A single out-of-range result in the context of a recent illness or stress is often temporary, and your GP can advise whether a repeat test or further investigation is needed. If your count is low (neutropenia), your GP will assess whether any current medications or recent illnesses might explain it, and whether additional testing is warranted. Significant neutropenia can increase susceptibility to bacterial infection, so it is not something to set aside without follow-up. If your count is high, your GP will consider whether this fits with any current symptoms (infection, inflammation) or medications. An isolated mild rise with no symptoms is usually not alarming, but a trend upward across several results, or a high count alongside abnormalities in other cell lines, warrants a closer look. Trends over time are more informative than a single reading. Always read this result in the context of your full FBC and your GP's clinical assessment. This page is general information and is not a substitute for advice from your GP.
Frequently asked questions
Test your neutrophils
NATA-accredited testing. Results in 2–5 days. No GP referral required.
View FBC