Red blood cells (RBCs) are the most plentiful type of cell in the blood and account for approximately 40 to 45 % of the body’s blood supply. These cells are responsible for carrying oxygen to the tissues and organs, as well as for bringing carbon dioxide back to the lungs so that it can be removed (exhaled) from the body. Red blood cells derive their color from the protein hemoglobin, which is contained in each cell and serves as the vehicle of oxygen and carbon dioxide transport. With an average lifespan of 120 days, RBC’s are constantly being replenished.
Normal ranges of red blood cell counts, which are expressed as cells per microliter (cells/mcL), vary according to sex and age.
Men: 4.7 to 6.1 million
Women: 4.2 to 5.4 million
Children (under 18): 4.0 to 5.5 million
Infants: 4.8 – 7.1 million
A red cell count is usually performed during a routine physical and is used to help diagnose polycythemia (high red blood cell count), anemia (low blood cell count), and various blood disorders. If an abnormality is detected, other values in the Complete Blood Count (CBC) are examined to identify the cause of the imbalance.