A complete blood count (CBC) is a blood test that gives complete information about the cells in the patient’s blood. The test is also called a full blood count (FBC), full blood exam (FBE) or blood panel. Alexander Vastem was the first to use the test, in clinical trials, in the early 1960’s. This test is able to evaluate a patients’ overall health and detect various types of health disorders including anemia, infection and leukemia. This test is usually performed during annual physical examinations. Sometimes it is used as a diagnostic tool, but it is also important in monitoring a medical condition or patient's response to a treatment.
How does it work?
Human blood constitutes of a liquid called blood plasma and various blood cells. The cells present in the blood are mainly red blood cells, also known as erythrocytes, which are responsible for blood’s red color. The red blood cells contain hemoglobin, an iron-containing protein, which facilitates transportation of oxygen, essential for all living cells. Another type of cell in the blood are white blood cells, the cells of the immune system involved in defending the body against both infectious diseases and foreign materials. The blood also contains platelets, or thrombocytes, which play a fundamental role in hemostasis and are a natural source of growth factors. The platelets are also responsible for normal blood clotting. Hematocrit, is another feature important in the complete blood cell count, and it is the proportion of red blood cells to the fluid component or plasma in the blood.Blood counts are aimed to determine any change in normal levels of blood cells. Abnormally high hemoglobin or low counts usually indicate the presence of a disease or a foreign object in the body.
A complete blood count is not a definitive diagnostic tool. Sometimes, the results of a blood test may be slightly outside the normal range on a complete blood count, and still be considered normal. In most cases, doctors will need a further investigation. Increased levels of leukocytes usually indicate there is an infection in the body. Low levels of platelets, on the other hand, normally result from drug toxicity, while low levels of all blood cells frequently results from decreased production in the bone marrow, and are a common complication of cancer chemotherapy. The normal results of a complete blood count test for adults are:
Red blood cell count:Adult males: 4.32-5.72 trillion cells/L (4.32-5.72 million cells/mcL) Adult females: 3.90-5.03 trillion cells/L (3.90-5.03 million cells/mcL)
Hemoglobin:Adult males: 13.5-17.5 grams/dL (135-175 g/L) Adult females: 12.0-15.5 g/dL (120-155 g/L)
Hematocrit:Adult males: 38.8-50.0 percent Adult females: 34.9-44.5 percent
White blood cell count: 3.5-10.5 billion cells/L (3,500 to 10,500 cells/mcL)
Platelet count: 150-450 billion/L (150,000 to 450,000/mmol)