Neutrophils are a type of white blood cell that act as the first line of defense in the immune system. They are the most common type of white blood cell and make up anywhere from 50% to 80% of all white blood cells in the body. Neutrophils are made in the bone marrow and migrate through the circulation system in the blood and tissues. They kill and digest bacteria and fungi to help the body fight infections and heal wounds.

A complete blood count (CBC) test can be used to check the health of neutrophils. This test examines the cells in a sample of blood and reflects how many cells are in the body. The normal range of neutrophils in a healthy adult is between 2,500 and 7,000 neutrophils per microliter of blood. An absolute neutrophil count (ANC) test can also be done as part of a CBC with differential to identify how many neutrophils are in the blood. If the neutrophil count is higher than usual, it may indicate an infection, illness, injury, physical or emotional stress, medication use, or inflammatory conditions. If the count is lower than usual, it may indicate a long-term infection, cancer, an autoimmune condition, or certain medications.

In summary, neutrophils are a type of white blood cell that play a crucial role in the immune system by fighting off infections and healing wounds. A blood test, such as a CBC or ANC, can be used to check the health of neutrophils and identify any underlying medical conditions that may be affecting their count.