Neutrophils (Absolute)

White blood cells are also called leukocytes and WBCs. They are a type of blood cell that is made in your bone marrow and found in your blood and lymph tissue (which is part of your lymphatic system). White blood cells are an important part of your immune system. When you are injured or sick, your white blood cells will travel through your bloodstream and tissues to where they are needed. There, they will help your body fight off the infection or disease.

There are five different types of white blood cells. Neutrophils are the most common type and are your body's main defense against infection when bacteria, viruses, or other germs enter your body. Lymphocytes include two main types of white blood cells: B cells and T cells. Monocytes kill bacteria, viruses, and other germs that may make you sick. Eosinophils defend against parasites and infections, and are also involved in allergies and help control inflammation. Basophils release enzymes during allergic reactions and asthma attacks.

A blood differential test measures the amount and/or percentage of each type of white blood cell. Another test called a white blood count (WBC) measures the total number of these cells in your blood.

A higher-than-normal neutrophil count (neutrophilia) is most often caused by a bacterial infection. It can also be caused by inflammation, physical or emotional stress, certain medicines such as steroids, smoking, and some blood cancers.

A lower-than-normal neutrophil count (neutropenia) raises the risk of getting infections, especially bacterial ones. Common causes include chemotherapy and other medicines, viral infections, autoimmune disease, vitamin B12 or folate deficiency, and bone marrow disorders.

Abnormal results don't always mean you have a condition that needs medical treatment. Some other factors that may affect your results can include physical injury or extreme stress, smoking, and alcohol use.

If your results seem abnormal, your provider may order other tests to help figure out the cause. To understand your results, your provider will also consider your symptoms, medical history, and the results of other blood tests.