Monocytes (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 of white blood cell 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; they also boost your body's immune response and clear away dead cells. 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 monocyte count (monocytosis) can be seen with chronic infections, autoimmune or inflammatory diseases, recovery from a previous infection, and some blood cancers such as chronic myelomonocytic leukemia.

A lower-than-normal monocyte count (monocytopenia) is less common but can be linked to bone marrow problems, severe infections, or treatments such as steroids or chemotherapy.

Abnormal results don't always mean you have a condition that needs medical treatment. Stress, recent illness, and pregnancy can also affect counts.

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.