Blood contains several types of cells including red blood cells that carry oxygen throughout the body, white blood cells that provide immunity and platelets that aid in clotting. White blood cells, also called leukocytes, function to fight bacterial, viral, parasitic, or fungal infections. The University of Maryland Medical Center reported in January 2008 that stem cells in the bone marrow produce approximately 95 percent of blood cells, including white blood cells. Testing for the total number of blood cells, the number of white blood cells and the percentage of each type of blood cell can provide information about overall health and disease progression.
Complete Blood Count
A complete blood cell count provides information on all cell types. A CBC determines the total number of red blood cells as well as the total amount of hemoglobin, the iron-containing protein responsible for carrying oxygen. A CBC also provides the hematocrit, the fraction of the blood composed of red blood cells, as described by MedLine Plus. A complete blood cell count also determines to total number of white blood cells.
Doctors perform a complete blood cell count to determine the presence of many conditions and diseases. The results of a complete blood cell count can reveal infections, problems with blood cell production and problems with fluid levels.
White Blood Cell Count
To determine the total number of white blood cells, doctors perform a white blood cell count test as part of a complete blood count. The WBC test will provide the total number of white blood cells including basophils, eosinophils, lymphocytes, monocytes and neutrophils. A normal result for a white blood cell count ranges from 4,500 to 10,000 white blood cells per microliter, according to MedLine Plus.
Doctors often order a white blood cell count to determine the presence of an infection. A high number of white blood cells, a condition known as leukocytosis, indicates an infectious disease, an inflammatory disease, leukemia or anemia. Increased emotional or physical stress can also cause a high level of white blood cells. A low level of white blood cells, known as leukopenia, can indicate a collagen-vascular disease such as lupus, disease of the liver or spleen or bone marrow failure. Exposure to radiation, such as through cancer treatments, can also cause leukopenia.
White Blood Cell Differential Count
A white blood cell differential count provides information on the percentage of each type of white blood cell in a sample of blood. Doctors use a white blood cell differential count to determine the body's ability to respond to and eliminate infection. This test can also detect the severity of an allergic reaction or a reaction to a medication, as described by Lab Tests Online. Doctors also perform a white blood cell differential count test to track the effects of chemotherapy or to determine the stage of leukemia--cancer of the bone marrow or blood.
