A complete blood count (CBC) is one of the most common blood tests that allow doctors to evaluate the overall health of a patient. CBC is used to find out the levels of cells in the blood, including the red blood cells, white blood cells, and platelets. The results of a CBC test help a doctor evaluate a range of health conditions, screen for diseases, and adjust treatments. A CBC test gives you a quick snapshot of your overall health.
What does a CBC test analyze?
A CBC test measures the quantity of three types of cells produced by the bone marrow and released into the blood:
Red blood cell count (RBC): They are the most common blood cell in the blood. These cells are responsible to carry oxygen through the body. The number of RBCs per cubic millimeter of blood is approximately 5.5 million. A low RBC is indicative of anaemia.
White blood cell count (WBC): It measures the number of white blood cells in your blood. These cells help your immune system fight off infections and attack by recognizing bacteria, viruses, and cancer cells, and marking them to be destroyed. High WBC also indicates problems with the bone marrow or immune system. However, on the other hand, a low WBC may indicate an autoimmune disorder destroying white blood cells.
Platelet count: Platelets play a crucial role in blood clotting. These are tiny and irregularly shaped blood cell pieces, or fragments, that become sticky whenever there is an injury as they help plug the site of the injury. The clot helps to stop the blood from leaving the body through the cut blood vessel. An abnormally low or high platelet count often indicates a medical condition.
Why it is done?
CBC is a useful test that helps to indicate if your blood is normal or if there are signs of a problem. It is usually performed before and after the surgery. Here is the list of health problems that can be identified by a CBC test.
Understanding your CBC results and ranges
After a blood sample is taken from a person, it is analyzed in a medical laboratory.
The following are normal CBC results for adults:
White blood cells: 4,500 to 11,000 cells per microliter (cells/mcL)
Red blood cells:
Male: 4.5 million to 5.9 million cells/mcL
Women: 4.1 million to 5.1 million cells/mcL
Male: 14 to 17.5 grams per deciliter (gm/dL) for men
Women: 12.3 to 15.3 gm/dL for women
Male: 41.5% to 50.4%
Women: 35.9% to 44.6%
Mean corpuscular volume: 80 to 96
Platelets: 150,000 to 450,000 platelets/mcL
If a result shows CBC too high or too low, it could signal a wide range of conditions and a person’s overall health. If there are signs and symptoms of an underlying problem, your doctor may suggest you undergo a routine checkup. People undergoing treatment for chronic conditions such as chronic kidney disease, ulcerative colitis, or rheumatoid arthritis, may have to visit a doctor regularly for a CBC checkup.
Preparations for the test
CBC is a fairly quick test that is conducted in most pathology laboratories. It is advisable to wear short-sleeved clothes during the test. A patient can have normal food and can have a normal intake of fluids as well. You are not required to fast unless there are some other tests to be done at the same time.