Neutrophil count (absolute, serum/plasma)

What Neutrophils Do in Your Body

Neutrophils are a critical part of your immune system. They detect and destroy bacteria, fungi, and some viruses. When your body detects an infection, neutrophils rush to the site to help fight it off. High levels may indicate an active infection, while very low levels could suggest immune dysfunction or certain medical conditions.

When This Test Might Be Ordered

Your doctor may order this test if you have symptoms like frequent infections, fever, fatigue, or signs of inflammation. It’s also used to monitor conditions like leukemia, autoimmune diseases, or after treatments that affect the immune system.

What to Expect Before the Test

No special preparation is needed. A blood sample will be drawn from a vein, usually in your arm. You may feel a slight pinch, but it’s quick and painless. If you’re on blood-thinning medication, let your doctor know before the test.

What the Results Mean

Results are typically reported as a count of neutrophils per microliter (µL) of blood. While reference ranges vary by lab, very high or very low counts can signal health concerns that need further evaluation.