Neutrophil Segment Count (Manual Differential)

This test is done to measure the number of neutrophils, a type of white blood cell that helps your body fight infection, most often as part of a complete blood count (CBC). It helps your doctor check how well your immune system is working, look for signs of infection or inflammation, and monitor conditions or treatments such as chemotherapy that can affect your blood cell counts.

Doctors may order this test to evaluate your immune response, check for infections, or monitor conditions like leukemia, autoimmune diseases, or chronic inflammation. It’s often part of a full blood count (CBC) to identify imbalances in white blood cell types.

Before the test, no special preparation is usually needed, and you can normally eat and drink unless your doctor gives you other instructions. Tell your healthcare provider about all medicines, vitamins, and supplements you take, because some drugs can change white blood cell counts. The sample is drawn from a vein in your arm, so wear clothing with a sleeve that is easy to roll up.

No special preparation is needed. You’ll have a small needle inserted into your arm or hand for a blood draw. The test is quick and typically done in a lab setting. If you’re on blood thinners, let your doctor know.

Your results are compared with the normal reference range, which for neutrophils is typically about 2,500 to 7,000 cells per microliter (cells/mcL) of blood. A count below this range is called neutropenia and may raise concern about infection risk, while a higher count, called neutrophilia, often points to infection, inflammation, or physical stress. Your doctor will interpret your numbers together with your symptoms, medications, and medical history.

Results show the proportion of neutrophils relative to other white blood cells. High levels may indicate infection, stress, or certain diseases, while low levels could signal immune suppression or other health issues. Your doctor will compare results to your overall health and symptoms.

Neutrophil levels can be affected by many common conditions. Bacterial infections often raise the count, while viral infections, some autoimmune diseases, and certain vitamin deficiencies can lower it. Bone marrow disorders, severe allergic reactions, and treatments such as chemotherapy or radiation therapy can also change your numbers. Temporary shifts may happen with exercise, emotional stress, pregnancy, or smoking.

Neutrophil counts can be affected by infections (like bacterial infections), chronic diseases (like diabetes or kidney disease), or medications. Severe neutropenia (very low counts) can increase infection risk, while very high counts may signal overactive immune responses.